APPLICATION OF CRUDE BENZENE PURIFICATION WASTE FOR COAL FLOTATION

V. M. Vityugin, S. A. Babenko, I. N. Nozhkina

(Presented by the scientific seminar of the Faculty of Chemical Technology)

Acid tar, a product of sulfuric-acid purification of crude benzene, is a waste product of coke-chemical production. At the Kemerovo Coke-Chemical Plant, 30–40 tons of acid tar are obtained monthly.

In terms of its physical properties, acid tar is a thick, viscous mass that becomes denser with time as a result of deeper polymerization of unsaturated hydrocarbons. The specific gravity of acid tar is 1.191.

Table 1

Chemical composition of acid tar

The content in acid tar of acid esters of sulfuric acid, capable of being readily saponified to alcohols, aromatic compounds, and sulfonic acids, makes it possible to assume that this product of coke-chemical production can be used in flotation as a frother.

A test of the frothing of acid tar by measuring the foam volume after 5 min of shaking 100 ml of solution at 19°C showed (Table 2) that the optimum dilution ratio is 1:20.

For neutralization of the tar, phenol-ammonia water was used—the water employed for coke quenching at the coke-chemical plant—with an ammonia content of 1% and phenol content of 2 g/l. The acid tar was diluted with phenol-ammonia water in a ratio of 1:20, heated for 5–10 min at a temperature of 50–60°C, and thoroughly ground until homogeneous. Judging from the foam volume after shaking under the above conditions, the frothing properties of acid tar neutralized with phenol-ammonia water improve. The foam volume is 515 cm³. The acid tar prepared in this way was used

as a frother in coal flotation. The flotation experiments were carried out in a mechanical-type machine with a chamber volume of 1 l. The flotation conditions were as follows: tap water, its temperature was 19°C, coal of size class —0.5+00 mm; before the experiments it was soaked overnight in water. Illuminating kerosene was used as the collector; in all experiments its consumption was constant and equal to 1 kg/t; the agitation time with kerosene was 3 min, the agitation time with the frother was 1 min, and the froth removal time was 1 min.

Table 2

Dependence of the foaming properties of acid resin on the degree of dilution with water

The results of flotation of coal from a number of Kuzbass mines with kerosene and acid resin at different consumptions of the latter are given in Tables 3, 4, and 5.

It can be seen from Tables 3–5 that the addition of acid resin to the pulp with kerosene increases the yield of the froth product, practically without lowering the quality of the concentrate (without frother the concentrate yield was: 35.2; 51.3 and 49.4%, while with the addition of 0.5 kg/t of acid resin the concentrate yield was, respectively: 55.7; 50.5 and 55.2%). Therefore, the use of acid resin as a frother increases the recovery of combustible matter into the concentrate to 62.1% versus 39.5% without acid resin for Babanakovskaya coals, and, respectively, for Chertinskaya coals—to 69.8 and 61.6% with acid resin versus 56.1% and 50.2% without acid resin. The optimum consumption of acid resin for the flotation of easily beneficiated Babanakovskaya coals is 0.5 kg/t, and for the difficult-to-beneficiate Chertinskaya coals—1 kg/t.

Table 3

Flotation of coal from the “Babanakovskaya” mine

Acid resin as a frother for coal flotation cannot be compared with pine oil. However, taking into account the insignificant cost of acid resin (equal to the cost of transportation to the beneficia-

... preparation plant), the latter may find application in coal flotation if the flotation tailings are used as an energy fuel.

Table 4

Flotation of coal from the Chertinskaya-1 mine

Table 5

Flotation of coal from the Chertinskaya-Zapadnaya mine