Coal Science
J.A. Pajares and J.M.D. Tasc6n (Editors) 9 1995 Elsevier Science B.V. All rights reserved.
1565
D i r e c t i o n s of development in coal cleanin~ A. A. Baichenko and S. I. Sritsko Institute of Coal, Russian Academy of Sciences, 21, K~kavichnikov st. 650610, Kemerovo, Russia
1. ABSTRA~ The c r e a t i o n of technoloffies of r a t i o n a l use of mineral resources comprisin~ complex e x t r a c t i o n of wastes with an account of environmental impact of minin~ e n t e r p r i s e s is p o s s i b l e only in wide a p p l i c a t i o n of the l a t e s t achievements of chemistry in minin~ industry. F i r s t of a l l i t concerns the use of f l o t a t i o n reagents f o r s e l e c t i v e s e p a r a t i o n of minerals, coagul a n t s , p o l y e l e c t r o l y t e s and polymer f l o c c u l a n t s to c o n t r o l the s t a b i l i t y of d i s p e r s e system in hydraulic mining, hydraulic t r a n s p o r t , thickening, f i l t r a t i o n , creanin~ of e f f l u e n t s . 2.
Igl"~lll~IOg
The n e c e s s i t y of takin~ nature p r o t e c t i o n measures c r e a t e d a complicated s i t u a t i o n in the coal p r e p a r a t i o n p l a n t s : savin~ f r e s h water, cleanin~ of e f f l u e n t s and dewaterin~ of f i n e s ( s p e c i a l l y in winter) force to apply t e c h n o l o g i c a l schemes with water o p e r a t i o n s playin~ the main p a r t . And j u s t water but not p r e p a r a t i o n o p e r a t i o n s consume the ms4 or c a p i t a l investments, maintenance and labour expenditures. Every year t h i s problem is becomin~ more acute. In the f i r s t instance i t concerns the int e n s i f i c a t i o n of f l o t a t i o n , thickenin~ f i l t r a t i o n of coal s l i mes and c l a r i f i c a t i o n of e f f l u e n t s .
1566 reazent consumption (2 kR/ton of aromatizied apolar reagent AAR-2 and 0,3 kz/ton of vat residue of buthyl alcohol VRBA which is added to the slurry as emulsions in several steps at flotation front) [3]. The flotation concentrate Roes to vacuum-filters where 10 R/ton of PEO is added. The filtrate is directed to the separats f lotat ion machine for select ire f lotat ion of the f ine part icles. This process is carried out with diluted slurries containR 30-40 R/I solids. As flotation reaRent VRBA is used only its emulsion is added fractionally - 40Z, 30Z and 30Z into the 1st, 2nd, and 5th chamber at the total flow rate of 50 R/ton [4]. Table Selective flotation of fine particles of the filtrate Classes,
Supply Q
Concentrate
lf, Z
Ad,z
Q
+25 6,86 26,3 25 - 10 1.18 4.5 10 - 5 2.53 9.7 5 - 0.0 15,,53 59.5 +0.0 26.10 100.0
8.5 15,1
6.60 1.0
12,0
2.35
1 " 1 . 0 14.95 10.6 24.90
Tai 1 inRs Ad,z
Q
i', Z
Ad,z
25.3 3,8
6.8 7.2
0.26 0.18
1,0 0.7
51.8 58.4
9.0
7.8
0,18
0,'7
66.2
5'7.3 95.4
8.4 7.9
0.58 1.20
2.2 4.6
?'9.0 68,,0
I,Z
Q - input, ton/hour; ]r- yied, A d - ash content. The results of flotation of the filtrates are presented in the table. It is seen that the main part of particles has the diameter less than 25 Inn. By the method described the hizh deRtee of' separation of coal and rock particles is reached: the flotation of particles of the diameter less than 5 ~m and ash of 11Z yields coal concentrate with ash of 8.4Z and the flotation tailinRs with ash of 79Z. So., the combine use of polymer flocculants and flotation reazents in the cycle of s of the slime water enables not only to intensity the processes of sedimentation, filtration and flotation but to reach the selectivity of separation
1567 2. ~ T S
A}G) D I ~ I O N
8.1. The intensive technolo~/ of slime water purification.
Therefore, the most r a t i o n a l way to r e a l i z e the sin~leste~e technological scheme is the i n t e n s i f i c a t i o n of f l o t a t i o n and f i l t r a t i o n processes usin~ more e f f e c t i v e f l o t o r e a ~ e n t s and f l o c c u l a n t s [1,2], of Berezovskaya Washery. Fi~.l ~ives the flow chart of s e l e c t i v e p u r i f i c a t i o n of slime waters by complex use of apolar reagents and f locculant (PEO).
AAR-2 ~J COBS ~J
slime water
,L
-+
MAI~ FLOTATION _
......
o_
_
concentrate
l wastes
FROTH REDUCTION .
.
.
.
~
PEO
FILTRATION Icake C O ~ ~ filtrate FLOTATION OF FILTRATE .
I
.
.
.
.
.
.
.
.
.
concentrate
9
,
wastes EO, VPK CLARIFICATION
I ........... sediment
Figure 1.
I.
. . . .
in circuiati6n
The points of introducin~ reagents iflto flowsheet for slime water p u r i f i c a t i o n .
the
The slime waters a f t e r dred~in~ s~mp ~o to the p r i n c i p a l f l o t a t i o n , the task of which is maximal e x t r a c t i o n of coal part i c l e s in f l o t a t i o n concentrate and obtainin~ the f l o t a t i o n tai l i n ~ s with high ash content. It is reached by some increase of
1568 of coal p a r t i c l e s as well. 4. (XR~N.OSIOMS Wide a p p l i c a t i o n of chemical reagents to control the s t a b i l i t y of n a t u r a l d i s p e r s i o n s c r e a t e s c o n d i t i o n s f o r introducin~ r e d i c a l l y new processes of r e g e n e r a t i o n of slime, mine and sewage waters, make the performance of the e x i s t i n ~ i n t e n s i f i e s the t e c h n o l o ~ of treatment of useful minerals and reduces the loss of c o n c e n t r a t e s improves t h e i r q u a l i t y and environement in the re~ion. Introduction of t e c h n o l o g i c a l processes of coagulation, f l o c c u l a t i o n , f l o t a t i o n and minimum use of reagents f o r them makes p o s s i b l e to lower sharply the consumption of r e a g e n t s and automotize individual t e c h n o l o g i c a l blocks ( f l o t a t i o n and f i l t r a t i o n of concentrates) without any dan~er of accumulatin~ f l o t a t i o n reagents in the recycled water. S e l e c t i o n of reagents, p r e p a r a t i o n of reagent s o l u t i o n s and choice of the p o i n t s of t h e i r i n t r o d u c t i o n into the technol o g i c a l process is to be made takin~ account of physical and chemical p r o p e r t i e s of water and raw m a t e r i a l of the ~iven enterprise.
1. A.A.Baichenko, A1.A.Baichenko. The use of polymers in closed water cycle in coal p r e p a r a t i o n p l a n t s . News of high schools. Minin~ Journal. No 4, p. 81-85 (1981). 2. I . R o i t e r . The use of f l o c c u l a n t s and polymers in coal prepar a t i o n . Gluckauf. No 19, p. 19-22 (1970). 2. A.A. Baichenko, A.A.Baran, N.S. Mitina. Treatment of recycled water by f l o c c u l a t i o n in coal preparation. Chemistry and wat e r technolo~/. Vol. 7, No 4, p. 28-42 (1985). 4. V.T.Tyurnikova, M.E.Naumov. The increase of f l o t a t i o n e f f e c t i v e n e s s . Moscow: Nedra, 224 p. (1980).