The need for the optimal selection of efficient filter media

ERMEDIA FORDEWATERING

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G

iven the best design of filtration plant in order to achieve acceptable levels of separation, there still remains the need for efficient cloth washing, and the use of the most suitable type of filter fabric. This is particularly true of modern, fully automatic liquid filtering and dewatering equipment which is more often integrated into the production process. Filter cloths tend to be of a synthetic monofilament or multifilament weave (polypropylene or polyamide-Rilsan in general) or a combination of both. The productivity can be seriously affected by the degree of efficiency in the automatic washing system. Here we look at an example, Cleveland Potash at its Boulby Mine in Cleveland, UK. Here two massive shafts to a depth of 1150 m enable the seam of potash - which is about 5 m thick - to be worked at anything up to 3 km from the coastline. Some 3 million tonnes of potash is mined in this way for use in the fertiliser industry and as rock salt. Potash ore mined at Boulby contains between 27% and 33% potash, and its release from the ore involves processes in which dewatering, drying and screening are highly important factors. A key section of the plant carries out the recovery of the potash using hot leach and filtration techniques; a 2 m x 2 m model 161 plate filter press recovers filtrate containing potash for further processing. With productivity being the most significant element of the overall performance, naturally the plant management began to look with great concern at the increase in downtime. Indeed, it was not prepared to accept some 12 hours downtime on a cloth wash. Thus the performance of the already fitted 161 plate filter and wash machine had to be considerably improved. It was at this point that Staffordshire, UK-based Latham Engineering Services was called in. Latham at once inspected, the situation, and was able to introduce ancillary equipment which caused an immediate improvement in plate separation, followed by the equally impressive introduction of an automatic low head washing system. As Phil Askew of Cleveland Potash comments, ‘The reduced wash cycle times achieved by Latham Engineering Services have proved to be of immense value to us.’ The problem of washing the cloth had admittedly been a hold-up, with it happening perhaps every 30 - 40 operaFiltration

& Separation

November/December

Laser

(CXD/CAIM)

Industri-TexLl

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tions. Washing had been synchronised with the separation of plates, and washing a filter cloth took anything up to 3 hours. Latham introduced the installation of automated washers. In addition to not requiring surveillance, the downtime was significantly reduced. The

need

Latham

for

correct

Engineering

filter

fabrics

Services was keen to

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0015-1882/95/US$7.00

a microscope

high preci.sz:on

designs

(photograph

courtesy

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link up with a company t,o the fore in textile technology, where its requirements in the use of the most advanced synthetic fibres and weave constructions could be met. Following worldwide research, Industri-Textil Job AI3 of Kinna, Sweden was selected as a partner. This immediately brought to Latham the full resources of a company devoted to the study and development of filter

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1995 Elsevier

Science

Ltd

949

ERMEDIA FORDEWATERING fabrics, to the extent that whatever the process characteristics required whether good cake release, optimum dry content, high capacity and high degree of separation etc. - the most suitable weave designs and materials would be used. Based at Kinna, just outside Gothenburg, Industri-Textil Job is housed in a 9000 m2 factory and offices. Here are all the required stages in the production chain, from fibre to ready-made product with the help of the most modern equipment. The annual production capacity exceeds 1 million m2 of technical raw weave. In its flexible needling and weaving line the company has the resources to customdesign technical felt and fabric products

with exactly the properties and functions required in the application. As the chemical industry develops new synthetic fibres, the company can produce weave types and fabrics which can give a new perspective for liquids filtration and dewatering, thus bringing a powerful extra dimension to Latham Engineering Services. The range covers filter plates from 250 mm in both standard and special versions. It is the subsequent processing in several stages that gives raw weaves and felts their final technical properties - permeability, surface structure, dimensional stability and resistance. All this represents a sound two-way partnership. Industri-Textil Job is currently installing Latham filter presses in

TEST EQUIPMENT

-

TAlLOR MADE -

TEST STANDS PERMEABILITY BURST

several locations in Scandinavia, including at a major motor manufacturing plant and at a refinery in Norway.

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‘L&&am E&gi7aeering S&es Unit 2, Btik iT&T,iz. Lane Pa&house West Estate CZWStMm, ~~~~~le-~~~~~~e ~i!s%&%~&hire ST5 7As, UK ~Tel: + 44 178,565364 Fatz^: f 44 1782 564886 ~~~~~~-Te~l Job AB Bos f4-4, S-511223 E&ma, Ed -f-46 3X4 13015 l%&: f 46 310 f&T45

SPECIAL

AUTOMATICALLY AND PORE SIZE

tibchn.

MACHINES ASSEMBLING

KNIFE PLEATERS UP TO 1500 mm PAPER, NON WOVEN, WIRE MESH AUTOMATICALLY CHANGE OF PLEAT HEIGHT 5-50 OR 20-100 mm

PRESSURE/THICKNESS

TEST RIGS FOR AIR FILTERS IS0 5011 PENETRATION CONTROLLED AUTOM. TEST RIGS FOR OIL FILTERS IS0 4548

ROTARY PLEATER ON REQUEST 1 AND 2 COMPONENT DOSING UNITS FOR ADHESIVE AND P.U.

MULTI PASS TEST RIGS IS0 4572 TAPPING MACHINES 1-4 HEADS 400 TAPS/HOUR AND HEAD 3/4” UNF 16. MAX. 11!2rr UNF 12. FORMING TO 3/4” UNFIG or Ml8 x I,5 SEMI OR FULLY AUTOMATICALLY

ALL TEST UNITS MANUAL OR PC CONTROLLED. PARTICLE COUNTERS ON REQUEST DRY LEAKAGE TEST RIGS TESTING THREADS - PRESSURE - LEAKAGE SEMI AND FULLY AUTOMATICALLY

BY PASS VALVE ASSEMBLING FULLY AUTOMATICALLY INCL. SPRING PRODUCTION

PLEASE SEND US YOUR INQUIRY FOR A FREE DETAliLED IBS ING.

QUOTATION

-BUERO SCHAEFER ’ H. LOENS TEL. -49 6467 8134 GERMANY

STR. 37 l 35116 HATZFELD FAX. -49 6467 637

IBS m

Filtration

& Separation

November/December

1995

951