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Role of Management in the Introduction of Automation with Special Reference to Mining and Mineral Processing
ROUND TABLE DISCUSSION
RT3
THE ROLE OF MANAGEMENT IN THE INTRODUCTION OF AUTOMATION WITH SPECIAL REFERENCE TO MINING AND MINERAL PROCESSING
PANELLISTS:
T.C. CROSBY (CHAIRMAN), D.A. VILJOEN, M.G. ATMORE
T.C. CROSBY:
2.
Project management's commitment to establish control philosophy and process operating knowledge with the operating management group so that sound decisions can be obtained during plant design. Operating and maintenance methods must be considered in order to provide wtll-designed control rooms, maintenance shops and spare parts.
3.
Operating management's commitmznt to follow through the difficult start-up ph~se and make the systems work as designed or implement changes if required. They must be willing to spend the time and money to provide trained operators and maintenance personnel and establish the attitude that the systems can, and will, work and be beneficial for good plant operations. To obtain this commitment, the operating management must actively participate in the plant design and decision-making processes.
4.
Competent control systems engineers who are knowledgeable of both the process dynamics and of the latest control equipment must be assigned to the project. They must not only be capable of des~ning and specifying suitable control systems equip~ent, but must also be able to plan and schedule the installation of the equipment so that the plant can be operated automatically at initial start-up. Their participation must continue through the initial plant operation to ensure that all controls are operating correctly on automatic.
5.
Construction management must be committed to install and test the equipment concurrently with other plant equipment so that the plant can start with all control equipment functioning.
6.
A team effort must exist during the design, installation and initial operation periods. Adjustments, and sometimes modifications, are required to insure proper operation prior to turning the systems over to the plant operator.
Management's commitment to automation determines the extent and success of automatic control in minerals processing plants. Most operating managers want to have the best, most ~odern and efficient plant, but this goal is rarely attained. From· White's (1) survey of U.S. minerals processing plants, it is obvious that several minerals processing plants in the U.S. have experienced dissatisfaction with control systems performance. Regrettably, comments made by plant personnel attest to our inability to provide satisfactory results. For many years, the failures of automation have been blamed on equipment manufacturers but substantial improvements in automatic control equipment have been accomplished (2-5). These developments have been successful for several years so that we must look for other reasons for the unsuccessful installations. The cement industry has attained a high degree of success in automating plants. It has been suggested (6) that "People factors are the major key in achieving successful, profitable automatic process control." Could the management of these "people factors" be the factor preventing successful automation? White (1) indicated surprise that "most successful instrumented installations seemed to be those where instrumentation was gradually installed in existing mills" and that the most serious problems exist in large mills designed and installed by contractors and vendors. This is not surprising since the installation of instrumentation in existing plants is a gradual process usually taken one step at a time by a relatively small group of permanent plant people. New plant installations, on the other hand, involve large systems that must be placed in operation within a short period of time and require the combined efforts of a large number of people, many of whom are not permanent plant people. REQUIREMENTS FOR SUCCESSFUL AUTOMATION 1.
Top management's commitment to provide the funds to purchase the equipment and to employ the people so that they can be trained to successfully utilize the systems.
Successful automation of existing plants, on the other hand, requires only four of the
757
above ingredients, namely: 1.
Top ~anagement's commitment to provide the funds and staff.
2.
Operating management's r.Jent.
3.
competent control systems engineer.
4.
Tea~
corr~it
effort.
When automation is gradually installed in existing mills, the capital cost is spread over several years and is often "hidden" under operating expense. The project management function is usually carried out by operating management and the process parameter is readily available, as the plant is operating. Most of the large minerals producers now have competent control systems engineers on their staffs, or have access to such people through either vendors or consultants. Another factor that does not exist when installing systems in existing plants is the completion schedule because the plant is operating and delays will not affect the plant production as it does in new plants. However, the involvement of a team which includes both experienced operating and control personnel is mandatory for the implementation of a successful system (7). Perhaps the largest factor contributing to the success of automation of existing plants is that the plant operating manager is responsible for requesting the funds and completing the installation. He is, therefore, highly committed to successful automation. The plant operations group know that they must live with their mistakes and also are well aware of their limitations, thus, their approach to automation tends to be much more conservative.
automation. During the design, construction and initial operation of these plants, the staff of control systems engineers from the plant operation group, were directly assigned to the project and had responsibility for the decisions made during design, purchasing, installation and start-up. These installations have all been very successful. The success of Cyprus Pima ~ining Company's introduction of automation and computer-based control systems into an existing plant are documented by Bassarer (3) and Bailey (4). Utilization of on-stream particle size analyzers and computer control indicate the success that can be attained by team efforts of plant management, equip~ent vendors and control systems eng~neers. Similar efforts in other copper concentrating plants indicate vendors interest and capability to install and test new devices in existing plants. This approach should be considered if the existing plant is small and cannot support an adequate staff of control systems personnel. The technical competence and capability to integrate control equipment into existing plants must be evaluated when selecting outside help since this is a vital part of the program. Many new plant facilities have successfully managed utilization of automatic systems. Newmont Mining Company's Carlin gold cyanide plant (8), although small by today's standards, is an excellent example of team effort and co~~itment on the part of top management, project manage~ent, operating management and the engineering construction contractor. Plant operations management recognized the importance of good maintenance early in the design phase and the maintenance staff was mobilized and participated in the construction, test and start-up of the plant. This participation helped resolve many of the problems that could have prevented timely utilization of automatic controls.
ANALYSIS OF SUCCESSFUL INSTALLATIONS A review of successful installation in both existing plants and new plants will identify the important factors required. During the late 1950's one of the United States fertilizer companies decided to build a copper concentrator. Like most copper plants of that time, it was built with a very minimum amount of automatic control equipment. Shortly after production began the company's top management recognised that the plant was not operating as satisfactorily as their chemical plants due to the lack of good automatic control. A control systems engineer was transferred to the new plant 'and given the responsibility to design and install control equipment. Standard instruments available at the time were installed. However, it became obvious to the systems engineer that many of the necessary measurements and control systems required for minerals plants did not exist. He, therefore, developed many special systems such as electro-pneumatic froth level control for flotation cells and gyratory crusher controls utilizing radiation level gauges, which were subsequently patented and sold. Other copper plants built during the 1960's by this company included a high degree of
Hanna Mining Company's efforts to automate two iron ore taconite plants is another fine example of successful installations. Recognizing their limited maintenance capability with computers and complex electronic controls, they decided to contract maintenance supervision of this equipment for the first year of operation. During this period the equipment vendors supervised and trained the maintenance personnel, ~stablished an adequate spare parts inventory, establisned maintenance programs, and modified troublesome systems. The need for this vendor service vanished as the mining company personnel attained the capability to carry out these functions. The Bougainville Copper Project is a good example of how the combined efforts of management from three co~~tries can successfully automate a major plant in a remote area of the world. The success of this installation, to a large extent, was due to the special efforts put forth to train the operating personnel (9). Special process simulators were developed ani bl
758
it should respond to process upsets before the plant was placed in operation. This project was not without its share of problems, particularly in the utilization of sonic level control of ore stockpiles and bins. Operations management, the control systems engineer, and the vendor made every effort to modify this equipment during the first year of operation before finally abandoning this control system. Their continuing commitment to successful automation has not diminished because they recognize that some failures may occur.
dangerous approach can produce a very negative attitude within the plant operations group. Once this attitude has been established, it may take years to overcome. In fact, if labour-saving systems are involved, management may never be allowed to install these systems in the future. To prevent this situation, it is imperative that reliable control systems be installed, tested and placed in operations at the time of initial plant operation. The importance of a team effort at the time of initial operation cannot be over-emphasized as this period is critical to the future utilization of automatic control.
Quite often, hydro-metallurgical plants contain processes that can be highly dangerous if not properly controlled. Many control systems used in nickel, copper and uranium hexafluoride plants must be utilized to maintain safe conditions. Installations of this type have a high degree of personnel commitment to successful operation particularly on the part of plant operators!
CONCLUSION
Many other examples exist throughout the world, each having particular problems such as: remote areas, lack of maintenance personnel, dangerous process requiring automatic control, unskilled plant operators, etc. These installations have been successful because the management involved recognized the problems and established plans to overcome these limitations. Occasionally, management has elected to minimize controls because of their belief that the potential problems exceed the benefits that can be obtained.
Many useful process measurement devices and sophisticated control systems have been developed to automatically control minerals beneficiation plants. The successful integration of this technology depends on our ability to provide project management, plant operating management, systems engineers, construction management, maintenance and operators with the proper knowledge, attitude and commitment to utilize these tools. If the people involved are not committed to make it work, it is better not to install the control system as history indicates that it will not be used. REFERENCES 1.
White, J.W. Survey of Automated Controls Generates Both Negative and Positive Feedback. Engineering and Mining Journal, Feb. 1974, pp. 59-66.
2.
Hemingway, D. A Review of the History and Present Status of Instrumentation in the Measurement and Control of Crushing and Grinding Circuits. Paper presented at the Instrument Society of American Conference, Oct. 1975, in Milwaukee, Wisconsin.
3.
Bassarear, J.H. and McQuie, G.R. On Stream Analysis of Particle Size. Mining Congress Journal, May 1972, p. 36.
4.
Bailey, J.E. and Carson, H.B. Cyprus Pima Mining Company's Computer Based Control System. Paper presented at the AIME Meeting, Feb. 1975, in New York, N.Y.
5.
Crosby, T.e. Operating Controls Review. Mining Engineering, Feb. 1973, pp.71-73.
6.
Gautier, E.H., Hurlbot, M.R. and Rich E.A. Recent Developments in Automation of Cement Plant. IEEE Transactions Vol. IGA 7 No. 4, July 1971, pp. 458-469.
7.
Bailey, J.E., Carson, H.B. Development of a Grinding Control System for a Copper Concentrator. Paper presented at the Instrument Society of America meeting, Oct. 1975.
8.
Mathews, Samuel W. Nevada's Mountain of Invisible Gold. National Geogrpahic, May 1968, pp. 668-679.
9.
Ballmer, R.W. The Bougainville Copper Project. Mining Congress Journal, April 1973, pp. 33-40.
ANALYSIS OF FAILURES The most frequent factor contributing to the failure of automation, whether it is a simple control system or a complex direct digital control system, is the failure to have the plant operations management involved in the design and construction of the plant. Many projects, particularly in remote parts of the world, do not hire the plant management or maintenance personnel until the facility is ready to operate. Thus, tte operating management is not equipped with the knowledge required to understand the systems or how they are to function. Under these conditions, the operating group must exert all of their efforts into placing the plant into production. For most minerals beneficiation plants, this means "Start on manual and worry about the automatic controls later". Another cause of failure is due to the owner's project manager often being re-assigned to another new project prior to start-up. Thus, he cannot complete his management functions. Occasionally, there is a tendancy to over-complicate or install high-level control such as direct digital computer control when building new minerals beneficiation plants without having previous experience with such equipment. Plant managers and project management often believe that they may never obtain the money for additional controls after startup. Over-zealous control systems engineers or equipment salesmen may also promote an excessive amount of instrumentation. This
759
D.A. VILJOEN: Operators probably feel justified in their criticism of managements' attempts at plant automation during the past ten or ~lfteen years. With hindsight o~analysis lS that certain of their criticis~ is soundly based, as we have fallen into many of the traps, described by Mr. Crosby, which await the uninitiated and inexperienced. To some extent, we like others, have been gUllty of combining the introduction of large control systems, comprising arrangements where the operator himself closes control loops reffiotely, as well as loops which are fully automated, with the commissioning of large new process plants. Thls has not been done with the philosophy that money for these controls might not be avallable at a later stage, but rather in a genuine effort to simplify plant operation. .Although in all instances systems were deslgned ~y our consulting metallurgical, mechanlcaL and electrical engineers and commissioned by trained operating personnel, the dlfflcultles lntroduced by this approach became eVldent In many instances. Initial plant start-up problems, in some cases ruled that commissioning of instrumentation had to wait. This inevitably led to the problem of motivating operating staff into commissioning, at a later stage, control systems with which they had learned to live without, and which they often regarded as belng merely the whim of outsiders. .The genuine efforts of management aiming to lnstrument and 'automate must therefore in the future be guided by past 'experience' which has highlighted the philosophy of introducing control systems gradually into existing plants. This approach could combine the policy of incorporating tried and trusted systems in new plant design, and at a later stage. bV involvement of plant management, designing and commissioning additional systems. Involvement of the plant management team backed up by the consultant familiar with previous successes and failures, can be regarded as an approach wlth the ingredients for SUCCESS. .Management should, however, be given credlt for the fact that its efforts in the past have provided a measure of success and a sound basis for future planning. ObJectlves have been, and will continue to be directed towards introducing operatlonal alds In the form of instruments and automation for process and operating staff optlmlsatlon, always having due regard for economic viability of each proposed control loop. To succeed in the future,management must ensure that its commitment includes the following essential ingredients~ 1.
A basic objective seeking to lmprove economic viability of process.
2.
Involvement of the plant operatlng and engineering team during design.
3.
The provision of adequately trained personnel for operating and maintaining systems.
760
4.
Selection, whenever possible, of systems and instruments which have previously succeeded.
5.
The ensurance that instrumentation is supplied by reputable firms with competent after-sales service facilities, and spare parts backup.
Finally it can be stated that the degree of our success can be measured by the fact that management continues to pursue fresh possibilities, cautiouslv perhaps, but with much more confidenc~ in the knowledge that past experience has provided a basis for selectivity regarding instruments and control strategies. r,j. G. ATMOR:::
For many years the control of grinding variables in milling plants has exercised peoples ~inds and only recently after very many tests has it become possible to convince management of the merits of a system such as the Autotronics mill control operating on particle size and density covered by Mokken and Volk in their paper. Practical work on this system began in our Group in 1973 and is only now being finally tested and checked on a commercial plant. In the two cases it will be used differently; Union Corpcration tends to favour a small number of large mills and individual controllers can be economically justified. We favour a large number of small mills and all that can be justified at present is the installation of a few units to monitor and control plant milling output. In our diamond recovery operations, single-loop control tests were begun some years ago. The next step was the acceptance of the concept of partially centralised.control with each section having an lndlvldual control centre. There followed the introduction of fully centralised control. This was operated by one or two men with outside operators available if an emergency arose. This was an important point since it gave the central operators confldence to push the circuit knowing that if they went too far help was at hand. It was obviously also important to management. Next a mini-computer was incorporated at Kleinzee. There were a number of problems not connected so much with the control loops but local conditions of remoteness and therefore difficulty of maintenance and from corrosive seashore conditions. However, it was proved that it was possible and a major plant at ADM was then equipped with a much larger system. It has since been refined and developed and this is very competently described in the paper by Franklin and Brimmer. The management problem here was different. In a process of this kind recovery of as near 100 percent as possible lS the prime prerequisite. Obviously production rate is important but far more important is that, having determined the throughput, the rate shall be as steady as possible since fluctuations are likely to result in a drop in recovery which cannot subsequently be compensated for since the norm is 100 percent. It will be appreciated that this is fundamentally dlfferent from the more usual mineral recovery circuit where a small drop at
high tonnage surge rates can often be compensated for during subsequent periods of low throughput when the recovery factor can be improved so as to exceed the average o~ say, 90 percent. The success with which both technical and financial management have been won over can be illustrated by a new project ERGO which is now being engineered. This operation, which will depend for its commercial success upon very effective marginal recovery of gold, uranium and pyrite from old gold mining residues, will draw its feed from a number of areas separated by many kilometres. Concentration by flotation will be practiced and the final residue disposed of at a central point. Particular points of concern are the extremely high plant throughput, the shortage of trained and experienced flotation plant operating staff, the very low head grades of the feed material and safety to per sonnel and equipmen. All these are accentuated by the dis ances between the operations. Elaborate systems for sensing and automatic con rol have been incorporated wherever possible in the process covering all .aspects of opera ion and manage men and technical accounting. In he treatmen plant itself, operations such as the following an~ covel'ed: ReagFJ""" r'eceiving control, all omatic inventor.) contro::', a 1tUfl'jati c n:::xj r.g and make-up of reagents. 1
Close control and additional alarming and fail-safe systems for acid supply and usage because of the dangers inherent in handling sulphuric acid. All solution and Fulp flows are monitored and controlled both in and out of the plar.t. Also automatically controlled are pH, density, addition. level, air agitation, pulp conditioning time, etc. Finally for rretallurgical accounting residues bott liqt;.id [,;1d solid and saleable products are con inuously moni ored and evaluated by means of au 0matic sampling with rapid on-line analysis in so~e cases. This has been set out only o ffiake the most important point tha there has been no query from any level of management as to the need for this degree of elabora ion. In fac it has been encouraged fully and this, in our Group, is some hing which would not have been the case in the past. purpos(o~'
Two main factors have contributed to form managements' attitude during this period. The first has been the introduction of systematic and continuing training and development of people within the organisa ion capable of designing this kind of system and considerable steps have been taken in this direction, although until fairly recently it was most likely to be the man who expressed interest in process control, while successfully operating in some other field, who would be developed in this way. These men have done very good work but now a more professional approach is being encouraged although there is still some distance to go in breaking down the largely artificial distinctions and divisions between different
761
disciplines to form an overall process control philosophy. Something also still has to be done in overcoming individual preferences and dislikes for systems or a particular manufacturer's equipment where this is biased. However, it has to be done with care particularly in remote places where reliability and confidence in the equipment may be more important than its great accuracy. It is far too easy to underestimate the problems of these remote places. It is often said that in almost all cases automatic control should be possible on initial commissioning of the plant. This may be something to be aimed at for the future, although I am not convinced of it personally. In any case in spite of the training being done throughout industry there are not nearly enough specialists for this to be successfully done in all cases. The problem with management arises when the system is installed and does not work immediately and all confidence is los. It may be that its lack of effectiveness has almost nothing to do with he control system itself and if the process has been badly designed or badly engineered there is no way that the availability of automatic control will assist in commisioning - perhaps the reverse. By all means allow for design, development and final incorporation of automation of the control systems initially installed, but do not slavishly insist on a fanfare of trumpets in the overture. One last point is the need for some independent supervision of individual control systems particularly when these are designed as a management aid for individual plants folloWing in sequence. Most operators and plant managers are honest but in some cases there is a certain amount of chiseling particularly in metallurgical accounting for plant efficiencies and product fed to the next operation. This can be overcome by the establishment of an independent overall mine and metallurgical accounting function. T. NI~~ stressed that automation must be developed as well as instrumentation and tha this involved a basic understanding of he process dynamics, which were no always known. Pulps in particular, being difficult materials. made this understanding a someimes formidable task. Con rol of pH, for example, can be accomplished with automatic loops, either with difficulty or easily, depending upon the nature of the medium. Process research is needed for individual plants, and to this end the cooperation and understanding of plant staff, research institutes and management is essential. Problematic cases have to be studied deeply and research must be backed by management. G.J. SMEETS stated that it was imperative to have confidence in the investment put into a plant. Lack of
confidence meant that facilities were not used, and conversely over-confidence led to process accidents. How to stop over confidence in instrumentation was most certainly a problem. S.K. DE KOK related his own experiences of management attitudes towards instrumentation over a period of twenty five years. In the early fifties the metallurgical department oft the Anglo Vaal Group had been allotted some Z40 000, a considerable SQ~ in those days, to instrument gold and uranium plants. Pneumatic instruments were chosen, together with various weighers and pH meters. Maintenance staff were attracted from the chemical industry and he South African Air Force and combined with the robustness and simplicity of the equipment, the instruments performed well and are still in operation today. This experience instilled much confidence in instrQ~ents and when the Prieska project was developed, the go-ahead was given for the installation of very sophisticated instrumentation and control loops. In retrospect, this decision has been viewed with bitter disillusionment because the remoteness of the mine has made it impossible to attract technicians to maintain the instruments and they have consequently fallen into disrepair and disuse. The lesson learnt from this experience is that there is insufficient maintenance manpower in the instruments field in South Africa. Instruments can, however, be useful as diagnostic pointers, as,for instance,in the case of the P.M.S. Autometrics particlesize analyser, which has shown the ill effects on a grinding circuit, when stopping and starting a component mill. Finally, it should be borne in mind that it is more sensible to build a well designed, lightly instrumented plant than to invest in a badly designed, heavily instrumented operation.
Computers could only be bought for sound reasons, amongst which were the functional need for the transfer of knowledge and technology. The main incentive of such expenditure should always be financial and automation should always have as its ultimate aim an increase in real profit. T.C. ROSBY referred to compu er installations in America, stating that these always required good justification and careful analysis beforehand. In the U.S.A. instrument technicians and electricians were presently on a par but the situation was changing and the status of technicians was being upgraded. K.J. ~~TD considered the mining industry to be unlque in that there was a high level of 'noise' in both the raw material and labour resources inputs. This complicated the task of instrumentation and control enormously and management should appreciate the randomness of the basic inputs, which meant that the process was continually changing. A.H. ATKINS ~as of the opinion that in the fields of automation a 31eat responsibility rested on the shoulders of management. It was possible to overcome major process disturbances without automatic control. There was a lack of communication between the two parties and maIlagement should clarify its priorities. '1).• C. CROSBY concurred entirely with the former speaker. There were several good examples of such co-ordination in America having led to very successful installations of automation.
H.L. NATTRASS believed that the automation of mineral processes requires a certain degree of innovation. Conservation was sound and necessary at times, but the readiness to take some element of risk was vital. Management had to be prepared to allow innovative processes to take place. E.T. WOODBURN thought that the discouragement of an enthusiastic instrumentation staff was wrong.
T.C. CROSBY questioned whether over confidence in instrumentation could do damage to a plant.
G.I. GOSSMAN backed all that Mr. Viljoen had said.
R.K. JASPAN was convinced of the advantages of automatic control and the related cost/profit advantages.
Perhaps we were too self critical of our instrumentation efforts; there were in fact many instruments that had operated successfully for a period of years. During the past twenT,y years instruments had become fashionable and due to the failure of some installations, instrumentation had earned a bad name. Much knowledge had been gained, however, and this would be of inestimable value in the future.
Management in South Africa tended to require over-justification for the installation of automation. In America, computing facilities were often installed for no other reason than to investigate automation and assess its potential in a particular plant. The salaries of instrument technicians in South Africa were too low.
K.J. SCOTT felt that management must help to provide conditions conducive to proving instruments.
M.G. ATMORE refuted the charge that computers be installed for experimental purposes only.
D.A. VILJOEN stated that instrumentation would be more successful if the commissioning of the instruments followed that of the plant.
W. WEIDEMANN made the point that operators are concerned with the process itself, whereas instrument engineers are primarily interested in instrumentation.
J.D.N. VAN WYK asked whether management
762
realised how important the role of instrumentation is. In the course of visiting four very similar factories, instrumentation in the first three had been little cared for and was barely operative, whereas in the fourth an enthusiastic and determined management had meant that the instrumentation was functioning well. T.C. CROSBY agreed that well motivated management was essential to the success of automation. H.E. COHEN said that instruments should be able to analyse the plant to ascertain whether it was operating correctly. Provided the instruments were available, the operation could be assessed.
763
RT3
THE ROLE OF MANAGEMENT IN THE INTRODUCTION OF AUTOMATION WITH SPECIAL REFERENCE TO MINING AND MINERAL PROCESSING
PANELLISTS:
T.C. CROSBY (CHAIRMAN), D.A. VILJOEN, M.G. ATMORE
T.C. CROSBY:
2.
Project management's commitment to establish control philosophy and process operating knowledge with the operating management group so that sound decisions can be obtained during plant design. Operating and maintenance methods must be considered in order to provide wtll-designed control rooms, maintenance shops and spare parts.
3.
Operating management's commitmznt to follow through the difficult start-up ph~se and make the systems work as designed or implement changes if required. They must be willing to spend the time and money to provide trained operators and maintenance personnel and establish the attitude that the systems can, and will, work and be beneficial for good plant operations. To obtain this commitment, the operating management must actively participate in the plant design and decision-making processes.
4.
Competent control systems engineers who are knowledgeable of both the process dynamics and of the latest control equipment must be assigned to the project. They must not only be capable of des~ning and specifying suitable control systems equip~ent, but must also be able to plan and schedule the installation of the equipment so that the plant can be operated automatically at initial start-up. Their participation must continue through the initial plant operation to ensure that all controls are operating correctly on automatic.
5.
Construction management must be committed to install and test the equipment concurrently with other plant equipment so that the plant can start with all control equipment functioning.
6.
A team effort must exist during the design, installation and initial operation periods. Adjustments, and sometimes modifications, are required to insure proper operation prior to turning the systems over to the plant operator.
Management's commitment to automation determines the extent and success of automatic control in minerals processing plants. Most operating managers want to have the best, most ~odern and efficient plant, but this goal is rarely attained. From· White's (1) survey of U.S. minerals processing plants, it is obvious that several minerals processing plants in the U.S. have experienced dissatisfaction with control systems performance. Regrettably, comments made by plant personnel attest to our inability to provide satisfactory results. For many years, the failures of automation have been blamed on equipment manufacturers but substantial improvements in automatic control equipment have been accomplished (2-5). These developments have been successful for several years so that we must look for other reasons for the unsuccessful installations. The cement industry has attained a high degree of success in automating plants. It has been suggested (6) that "People factors are the major key in achieving successful, profitable automatic process control." Could the management of these "people factors" be the factor preventing successful automation? White (1) indicated surprise that "most successful instrumented installations seemed to be those where instrumentation was gradually installed in existing mills" and that the most serious problems exist in large mills designed and installed by contractors and vendors. This is not surprising since the installation of instrumentation in existing plants is a gradual process usually taken one step at a time by a relatively small group of permanent plant people. New plant installations, on the other hand, involve large systems that must be placed in operation within a short period of time and require the combined efforts of a large number of people, many of whom are not permanent plant people. REQUIREMENTS FOR SUCCESSFUL AUTOMATION 1.
Top management's commitment to provide the funds to purchase the equipment and to employ the people so that they can be trained to successfully utilize the systems.
Successful automation of existing plants, on the other hand, requires only four of the
757
above ingredients, namely: 1.
Top ~anagement's commitment to provide the funds and staff.
2.
Operating management's r.Jent.
3.
competent control systems engineer.
4.
Tea~
corr~it
effort.
When automation is gradually installed in existing mills, the capital cost is spread over several years and is often "hidden" under operating expense. The project management function is usually carried out by operating management and the process parameter is readily available, as the plant is operating. Most of the large minerals producers now have competent control systems engineers on their staffs, or have access to such people through either vendors or consultants. Another factor that does not exist when installing systems in existing plants is the completion schedule because the plant is operating and delays will not affect the plant production as it does in new plants. However, the involvement of a team which includes both experienced operating and control personnel is mandatory for the implementation of a successful system (7). Perhaps the largest factor contributing to the success of automation of existing plants is that the plant operating manager is responsible for requesting the funds and completing the installation. He is, therefore, highly committed to successful automation. The plant operations group know that they must live with their mistakes and also are well aware of their limitations, thus, their approach to automation tends to be much more conservative.
automation. During the design, construction and initial operation of these plants, the staff of control systems engineers from the plant operation group, were directly assigned to the project and had responsibility for the decisions made during design, purchasing, installation and start-up. These installations have all been very successful. The success of Cyprus Pima ~ining Company's introduction of automation and computer-based control systems into an existing plant are documented by Bassarer (3) and Bailey (4). Utilization of on-stream particle size analyzers and computer control indicate the success that can be attained by team efforts of plant management, equip~ent vendors and control systems eng~neers. Similar efforts in other copper concentrating plants indicate vendors interest and capability to install and test new devices in existing plants. This approach should be considered if the existing plant is small and cannot support an adequate staff of control systems personnel. The technical competence and capability to integrate control equipment into existing plants must be evaluated when selecting outside help since this is a vital part of the program. Many new plant facilities have successfully managed utilization of automatic systems. Newmont Mining Company's Carlin gold cyanide plant (8), although small by today's standards, is an excellent example of team effort and co~~itment on the part of top management, project manage~ent, operating management and the engineering construction contractor. Plant operations management recognized the importance of good maintenance early in the design phase and the maintenance staff was mobilized and participated in the construction, test and start-up of the plant. This participation helped resolve many of the problems that could have prevented timely utilization of automatic controls.
ANALYSIS OF SUCCESSFUL INSTALLATIONS A review of successful installation in both existing plants and new plants will identify the important factors required. During the late 1950's one of the United States fertilizer companies decided to build a copper concentrator. Like most copper plants of that time, it was built with a very minimum amount of automatic control equipment. Shortly after production began the company's top management recognised that the plant was not operating as satisfactorily as their chemical plants due to the lack of good automatic control. A control systems engineer was transferred to the new plant 'and given the responsibility to design and install control equipment. Standard instruments available at the time were installed. However, it became obvious to the systems engineer that many of the necessary measurements and control systems required for minerals plants did not exist. He, therefore, developed many special systems such as electro-pneumatic froth level control for flotation cells and gyratory crusher controls utilizing radiation level gauges, which were subsequently patented and sold. Other copper plants built during the 1960's by this company included a high degree of
Hanna Mining Company's efforts to automate two iron ore taconite plants is another fine example of successful installations. Recognizing their limited maintenance capability with computers and complex electronic controls, they decided to contract maintenance supervision of this equipment for the first year of operation. During this period the equipment vendors supervised and trained the maintenance personnel, ~stablished an adequate spare parts inventory, establisned maintenance programs, and modified troublesome systems. The need for this vendor service vanished as the mining company personnel attained the capability to carry out these functions. The Bougainville Copper Project is a good example of how the combined efforts of management from three co~~tries can successfully automate a major plant in a remote area of the world. The success of this installation, to a large extent, was due to the special efforts put forth to train the operating personnel (9). Special process simulators were developed ani bl
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it should respond to process upsets before the plant was placed in operation. This project was not without its share of problems, particularly in the utilization of sonic level control of ore stockpiles and bins. Operations management, the control systems engineer, and the vendor made every effort to modify this equipment during the first year of operation before finally abandoning this control system. Their continuing commitment to successful automation has not diminished because they recognize that some failures may occur.
dangerous approach can produce a very negative attitude within the plant operations group. Once this attitude has been established, it may take years to overcome. In fact, if labour-saving systems are involved, management may never be allowed to install these systems in the future. To prevent this situation, it is imperative that reliable control systems be installed, tested and placed in operations at the time of initial plant operation. The importance of a team effort at the time of initial operation cannot be over-emphasized as this period is critical to the future utilization of automatic control.
Quite often, hydro-metallurgical plants contain processes that can be highly dangerous if not properly controlled. Many control systems used in nickel, copper and uranium hexafluoride plants must be utilized to maintain safe conditions. Installations of this type have a high degree of personnel commitment to successful operation particularly on the part of plant operators!
CONCLUSION
Many other examples exist throughout the world, each having particular problems such as: remote areas, lack of maintenance personnel, dangerous process requiring automatic control, unskilled plant operators, etc. These installations have been successful because the management involved recognized the problems and established plans to overcome these limitations. Occasionally, management has elected to minimize controls because of their belief that the potential problems exceed the benefits that can be obtained.
Many useful process measurement devices and sophisticated control systems have been developed to automatically control minerals beneficiation plants. The successful integration of this technology depends on our ability to provide project management, plant operating management, systems engineers, construction management, maintenance and operators with the proper knowledge, attitude and commitment to utilize these tools. If the people involved are not committed to make it work, it is better not to install the control system as history indicates that it will not be used. REFERENCES 1.
White, J.W. Survey of Automated Controls Generates Both Negative and Positive Feedback. Engineering and Mining Journal, Feb. 1974, pp. 59-66.
2.
Hemingway, D. A Review of the History and Present Status of Instrumentation in the Measurement and Control of Crushing and Grinding Circuits. Paper presented at the Instrument Society of American Conference, Oct. 1975, in Milwaukee, Wisconsin.
3.
Bassarear, J.H. and McQuie, G.R. On Stream Analysis of Particle Size. Mining Congress Journal, May 1972, p. 36.
4.
Bailey, J.E. and Carson, H.B. Cyprus Pima Mining Company's Computer Based Control System. Paper presented at the AIME Meeting, Feb. 1975, in New York, N.Y.
5.
Crosby, T.e. Operating Controls Review. Mining Engineering, Feb. 1973, pp.71-73.
6.
Gautier, E.H., Hurlbot, M.R. and Rich E.A. Recent Developments in Automation of Cement Plant. IEEE Transactions Vol. IGA 7 No. 4, July 1971, pp. 458-469.
7.
Bailey, J.E., Carson, H.B. Development of a Grinding Control System for a Copper Concentrator. Paper presented at the Instrument Society of America meeting, Oct. 1975.
8.
Mathews, Samuel W. Nevada's Mountain of Invisible Gold. National Geogrpahic, May 1968, pp. 668-679.
9.
Ballmer, R.W. The Bougainville Copper Project. Mining Congress Journal, April 1973, pp. 33-40.
ANALYSIS OF FAILURES The most frequent factor contributing to the failure of automation, whether it is a simple control system or a complex direct digital control system, is the failure to have the plant operations management involved in the design and construction of the plant. Many projects, particularly in remote parts of the world, do not hire the plant management or maintenance personnel until the facility is ready to operate. Thus, tte operating management is not equipped with the knowledge required to understand the systems or how they are to function. Under these conditions, the operating group must exert all of their efforts into placing the plant into production. For most minerals beneficiation plants, this means "Start on manual and worry about the automatic controls later". Another cause of failure is due to the owner's project manager often being re-assigned to another new project prior to start-up. Thus, he cannot complete his management functions. Occasionally, there is a tendancy to over-complicate or install high-level control such as direct digital computer control when building new minerals beneficiation plants without having previous experience with such equipment. Plant managers and project management often believe that they may never obtain the money for additional controls after startup. Over-zealous control systems engineers or equipment salesmen may also promote an excessive amount of instrumentation. This
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D.A. VILJOEN: Operators probably feel justified in their criticism of managements' attempts at plant automation during the past ten or ~lfteen years. With hindsight o~analysis lS that certain of their criticis~ is soundly based, as we have fallen into many of the traps, described by Mr. Crosby, which await the uninitiated and inexperienced. To some extent, we like others, have been gUllty of combining the introduction of large control systems, comprising arrangements where the operator himself closes control loops reffiotely, as well as loops which are fully automated, with the commissioning of large new process plants. Thls has not been done with the philosophy that money for these controls might not be avallable at a later stage, but rather in a genuine effort to simplify plant operation. .Although in all instances systems were deslgned ~y our consulting metallurgical, mechanlcaL and electrical engineers and commissioned by trained operating personnel, the dlfflcultles lntroduced by this approach became eVldent In many instances. Initial plant start-up problems, in some cases ruled that commissioning of instrumentation had to wait. This inevitably led to the problem of motivating operating staff into commissioning, at a later stage, control systems with which they had learned to live without, and which they often regarded as belng merely the whim of outsiders. .The genuine efforts of management aiming to lnstrument and 'automate must therefore in the future be guided by past 'experience' which has highlighted the philosophy of introducing control systems gradually into existing plants. This approach could combine the policy of incorporating tried and trusted systems in new plant design, and at a later stage. bV involvement of plant management, designing and commissioning additional systems. Involvement of the plant management team backed up by the consultant familiar with previous successes and failures, can be regarded as an approach wlth the ingredients for SUCCESS. .Management should, however, be given credlt for the fact that its efforts in the past have provided a measure of success and a sound basis for future planning. ObJectlves have been, and will continue to be directed towards introducing operatlonal alds In the form of instruments and automation for process and operating staff optlmlsatlon, always having due regard for economic viability of each proposed control loop. To succeed in the future,management must ensure that its commitment includes the following essential ingredients~ 1.
A basic objective seeking to lmprove economic viability of process.
2.
Involvement of the plant operatlng and engineering team during design.
3.
The provision of adequately trained personnel for operating and maintaining systems.
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4.
Selection, whenever possible, of systems and instruments which have previously succeeded.
5.
The ensurance that instrumentation is supplied by reputable firms with competent after-sales service facilities, and spare parts backup.
Finally it can be stated that the degree of our success can be measured by the fact that management continues to pursue fresh possibilities, cautiouslv perhaps, but with much more confidenc~ in the knowledge that past experience has provided a basis for selectivity regarding instruments and control strategies. r,j. G. ATMOR:::
For many years the control of grinding variables in milling plants has exercised peoples ~inds and only recently after very many tests has it become possible to convince management of the merits of a system such as the Autotronics mill control operating on particle size and density covered by Mokken and Volk in their paper. Practical work on this system began in our Group in 1973 and is only now being finally tested and checked on a commercial plant. In the two cases it will be used differently; Union Corpcration tends to favour a small number of large mills and individual controllers can be economically justified. We favour a large number of small mills and all that can be justified at present is the installation of a few units to monitor and control plant milling output. In our diamond recovery operations, single-loop control tests were begun some years ago. The next step was the acceptance of the concept of partially centralised.control with each section having an lndlvldual control centre. There followed the introduction of fully centralised control. This was operated by one or two men with outside operators available if an emergency arose. This was an important point since it gave the central operators confldence to push the circuit knowing that if they went too far help was at hand. It was obviously also important to management. Next a mini-computer was incorporated at Kleinzee. There were a number of problems not connected so much with the control loops but local conditions of remoteness and therefore difficulty of maintenance and from corrosive seashore conditions. However, it was proved that it was possible and a major plant at ADM was then equipped with a much larger system. It has since been refined and developed and this is very competently described in the paper by Franklin and Brimmer. The management problem here was different. In a process of this kind recovery of as near 100 percent as possible lS the prime prerequisite. Obviously production rate is important but far more important is that, having determined the throughput, the rate shall be as steady as possible since fluctuations are likely to result in a drop in recovery which cannot subsequently be compensated for since the norm is 100 percent. It will be appreciated that this is fundamentally dlfferent from the more usual mineral recovery circuit where a small drop at
high tonnage surge rates can often be compensated for during subsequent periods of low throughput when the recovery factor can be improved so as to exceed the average o~ say, 90 percent. The success with which both technical and financial management have been won over can be illustrated by a new project ERGO which is now being engineered. This operation, which will depend for its commercial success upon very effective marginal recovery of gold, uranium and pyrite from old gold mining residues, will draw its feed from a number of areas separated by many kilometres. Concentration by flotation will be practiced and the final residue disposed of at a central point. Particular points of concern are the extremely high plant throughput, the shortage of trained and experienced flotation plant operating staff, the very low head grades of the feed material and safety to per sonnel and equipmen. All these are accentuated by the dis ances between the operations. Elaborate systems for sensing and automatic con rol have been incorporated wherever possible in the process covering all .aspects of opera ion and manage men and technical accounting. In he treatmen plant itself, operations such as the following an~ covel'ed: ReagFJ""" r'eceiving control, all omatic inventor.) contro::', a 1tUfl'jati c n:::xj r.g and make-up of reagents. 1
Close control and additional alarming and fail-safe systems for acid supply and usage because of the dangers inherent in handling sulphuric acid. All solution and Fulp flows are monitored and controlled both in and out of the plar.t. Also automatically controlled are pH, density, addition. level, air agitation, pulp conditioning time, etc. Finally for rretallurgical accounting residues bott liqt;.id [,;1d solid and saleable products are con inuously moni ored and evaluated by means of au 0matic sampling with rapid on-line analysis in so~e cases. This has been set out only o ffiake the most important point tha there has been no query from any level of management as to the need for this degree of elabora ion. In fac it has been encouraged fully and this, in our Group, is some hing which would not have been the case in the past. purpos(o~'
Two main factors have contributed to form managements' attitude during this period. The first has been the introduction of systematic and continuing training and development of people within the organisa ion capable of designing this kind of system and considerable steps have been taken in this direction, although until fairly recently it was most likely to be the man who expressed interest in process control, while successfully operating in some other field, who would be developed in this way. These men have done very good work but now a more professional approach is being encouraged although there is still some distance to go in breaking down the largely artificial distinctions and divisions between different
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disciplines to form an overall process control philosophy. Something also still has to be done in overcoming individual preferences and dislikes for systems or a particular manufacturer's equipment where this is biased. However, it has to be done with care particularly in remote places where reliability and confidence in the equipment may be more important than its great accuracy. It is far too easy to underestimate the problems of these remote places. It is often said that in almost all cases automatic control should be possible on initial commissioning of the plant. This may be something to be aimed at for the future, although I am not convinced of it personally. In any case in spite of the training being done throughout industry there are not nearly enough specialists for this to be successfully done in all cases. The problem with management arises when the system is installed and does not work immediately and all confidence is los. It may be that its lack of effectiveness has almost nothing to do with he control system itself and if the process has been badly designed or badly engineered there is no way that the availability of automatic control will assist in commisioning - perhaps the reverse. By all means allow for design, development and final incorporation of automation of the control systems initially installed, but do not slavishly insist on a fanfare of trumpets in the overture. One last point is the need for some independent supervision of individual control systems particularly when these are designed as a management aid for individual plants folloWing in sequence. Most operators and plant managers are honest but in some cases there is a certain amount of chiseling particularly in metallurgical accounting for plant efficiencies and product fed to the next operation. This can be overcome by the establishment of an independent overall mine and metallurgical accounting function. T. NI~~ stressed that automation must be developed as well as instrumentation and tha this involved a basic understanding of he process dynamics, which were no always known. Pulps in particular, being difficult materials. made this understanding a someimes formidable task. Con rol of pH, for example, can be accomplished with automatic loops, either with difficulty or easily, depending upon the nature of the medium. Process research is needed for individual plants, and to this end the cooperation and understanding of plant staff, research institutes and management is essential. Problematic cases have to be studied deeply and research must be backed by management. G.J. SMEETS stated that it was imperative to have confidence in the investment put into a plant. Lack of
confidence meant that facilities were not used, and conversely over-confidence led to process accidents. How to stop over confidence in instrumentation was most certainly a problem. S.K. DE KOK related his own experiences of management attitudes towards instrumentation over a period of twenty five years. In the early fifties the metallurgical department oft the Anglo Vaal Group had been allotted some Z40 000, a considerable SQ~ in those days, to instrument gold and uranium plants. Pneumatic instruments were chosen, together with various weighers and pH meters. Maintenance staff were attracted from the chemical industry and he South African Air Force and combined with the robustness and simplicity of the equipment, the instruments performed well and are still in operation today. This experience instilled much confidence in instrQ~ents and when the Prieska project was developed, the go-ahead was given for the installation of very sophisticated instrumentation and control loops. In retrospect, this decision has been viewed with bitter disillusionment because the remoteness of the mine has made it impossible to attract technicians to maintain the instruments and they have consequently fallen into disrepair and disuse. The lesson learnt from this experience is that there is insufficient maintenance manpower in the instruments field in South Africa. Instruments can, however, be useful as diagnostic pointers, as,for instance,in the case of the P.M.S. Autometrics particlesize analyser, which has shown the ill effects on a grinding circuit, when stopping and starting a component mill. Finally, it should be borne in mind that it is more sensible to build a well designed, lightly instrumented plant than to invest in a badly designed, heavily instrumented operation.
Computers could only be bought for sound reasons, amongst which were the functional need for the transfer of knowledge and technology. The main incentive of such expenditure should always be financial and automation should always have as its ultimate aim an increase in real profit. T.C. ROSBY referred to compu er installations in America, stating that these always required good justification and careful analysis beforehand. In the U.S.A. instrument technicians and electricians were presently on a par but the situation was changing and the status of technicians was being upgraded. K.J. ~~TD considered the mining industry to be unlque in that there was a high level of 'noise' in both the raw material and labour resources inputs. This complicated the task of instrumentation and control enormously and management should appreciate the randomness of the basic inputs, which meant that the process was continually changing. A.H. ATKINS ~as of the opinion that in the fields of automation a 31eat responsibility rested on the shoulders of management. It was possible to overcome major process disturbances without automatic control. There was a lack of communication between the two parties and maIlagement should clarify its priorities. '1).• C. CROSBY concurred entirely with the former speaker. There were several good examples of such co-ordination in America having led to very successful installations of automation.
H.L. NATTRASS believed that the automation of mineral processes requires a certain degree of innovation. Conservation was sound and necessary at times, but the readiness to take some element of risk was vital. Management had to be prepared to allow innovative processes to take place. E.T. WOODBURN thought that the discouragement of an enthusiastic instrumentation staff was wrong.
T.C. CROSBY questioned whether over confidence in instrumentation could do damage to a plant.
G.I. GOSSMAN backed all that Mr. Viljoen had said.
R.K. JASPAN was convinced of the advantages of automatic control and the related cost/profit advantages.
Perhaps we were too self critical of our instrumentation efforts; there were in fact many instruments that had operated successfully for a period of years. During the past twenT,y years instruments had become fashionable and due to the failure of some installations, instrumentation had earned a bad name. Much knowledge had been gained, however, and this would be of inestimable value in the future.
Management in South Africa tended to require over-justification for the installation of automation. In America, computing facilities were often installed for no other reason than to investigate automation and assess its potential in a particular plant. The salaries of instrument technicians in South Africa were too low.
K.J. SCOTT felt that management must help to provide conditions conducive to proving instruments.
M.G. ATMORE refuted the charge that computers be installed for experimental purposes only.
D.A. VILJOEN stated that instrumentation would be more successful if the commissioning of the instruments followed that of the plant.
W. WEIDEMANN made the point that operators are concerned with the process itself, whereas instrument engineers are primarily interested in instrumentation.
J.D.N. VAN WYK asked whether management
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realised how important the role of instrumentation is. In the course of visiting four very similar factories, instrumentation in the first three had been little cared for and was barely operative, whereas in the fourth an enthusiastic and determined management had meant that the instrumentation was functioning well. T.C. CROSBY agreed that well motivated management was essential to the success of automation. H.E. COHEN said that instruments should be able to analyse the plant to ascertain whether it was operating correctly. Provided the instruments were available, the operation could be assessed.
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