SU990841A1 - Method for removing arsenic from lead- and zinc-bearing dusts - Google Patents

Description

This invention relates to non-ferrous metallurgy, in particular, to methods for removing a mouse from lead-zinc dusts.

A known method for extracting mice from tin-made dusts, in which mice containing tin dust are mixed with soda pulp, dried, and then calcined at 500–600 ° C for 2–4 hours in an oxidizing atmosphere, i.

The disadvantage of this method is the removal of the mouse in the highly toxic form of calcium or sodium arsenates, which requires the construction of special expensive disposal facilities.

The closest in technical essence and the achieved result is the method of removing the mouse from lead-zinc dusts, including leaching with a solution of sulfide, sodium, followed by precipitation of the mouse from the solution t2.

 The disadvantages of this method are also the removal of the arsenic in a highly toxic form, the high consumption of expensive sodium sulfide reagent, a three-step leaching at high temperature.

; The aim of the invention is to display the mouse in a non-toxic sulfide form, reducing the consumption of sulfide c. rub and reduce the number of operations.

The goal is achieved according to the method of removal. a lead-zinc dust mouse, which includes leaching with sodium sulfide solution followed by precipitation. By moving the mouse out of solution, the dust is pre-sulphidized with sulfur, at 325-350 ° C for 105-120 minutes, leached at a ratio of sulfide 5 and sodium to mouse (3.4: -3.5): 1 and precipitated sulfides of the mouse ka in a known way.

For the experiments, converter dust containing,%: P b 4 5;

20 2n 15.9; C 2.2; Se 0.5; Sb 0.8; As 5.63. The mouse is found in the form of lead arsenate and zinc, as well as trioxide.

25

To determine the optimum sulfiding temperature, experiments were carried out at 35% sulfur consumption by the weight of dust and a duration of 120 minutes, weighed dust, 100 g. The results are shown in Table 1. Table 1. As can be seen in Fig. 1, complete suprising of the pyrrh is achieved in the range of 325–350 ° C. As the temperature increases, the loss of the mouse to the gas phase in the form of trioxide increases, which is associated with its large elasticity. The optimum sulfur consumption is determined under the following conditions: temp. The sulphidation course lasts 120 minutes, the charge is 100 g. The results are shown in Table. 2 and 3. From tab. 2 that 32 sulfur from the weight of the dust is sufficient to completely sulfidize the dust. The optimal duration of sulphidation is set at 32 sulfur consumption from the weight of dust, a temperature of 30 ° C, and a weight of 100 g. From the table. 3, it follows that for the full sulfiding of the dust, the duration of exposure is 105-120 minutes. The calcine obtained is used to leach the arsenic from it with a solution of sodium sulfide. The results of experiments to determine the optimal leaching parameters of the mouse from the resulting sulfide calcine are given in Table. 4. As can be seen from the table. 4, experiment 8 corresponds to the optimal condition where W: T 3: 1, t, Na2.S: As (3.4-3.5): and the duration is 120 min. PRI EMER. 100 g of dust containing 5.63% As is mixed with 16 g of sulfur and held for 120 minutes under argon atmosphere. A portion of a cooled cinder {100 g) containing 4.85 g As is leached with a solution (300 ml), 17 g N35.5 at 8 ° C for 120 minutes. Removing the mouse in solution is 98.6%. From the solution, mouse a precipitates in the form of sulfides with sulfuric acid at pH 2 in a known manner. The advantage of the proposed method over the known one is the combination of reducing the consumption of expensive N3.5 and removing the mouse in a non-toxic sulfide form that does not require disposal. Even if it is necessary to dispose of 1 ton of the mouse in the form of sulphides, it costs 20 times less than substandard calcium arsenates. Comparison of costs for removal and disposal of 1 ton of mouse by the known and proposed methods is given in Table. 5. Cost 1. t Na S 200 rub., And sulfur 60 rub. As can be seen, according to the proposed method, the removal of 1 ;, mouse and its burial without taking into account operating costs is 2.8 times less than what is known. Table

Sulfur consumption of dust weight

The amount of sulfide% mouse,%

25 30 32

25

table 2

The amount of oxide mouse,%

10.4

0.4

No Duration, Number of sul minysh,% I 60.. 84.7, 9 10599.7 120100 ExperienceApplication conditions F: T f f ..min t, c j F: T

5: 1

120

80 80 80 80 70 60 70 80 70

120 5: 1 5: 1

120, 5: 1

120 5: 1

120

120 5: 1 5: 1

90 3: 1

120

120 4: 1

Consumption

Burial costs,

rub.

2000

ten

Famous

Proposed 2.5 500

12.7

87.4

2.1 97.9

1.3 98.5

1.5 98.6

3.4 96.6

5.9 94.0

4.6 95.5

1.6 98.4

5.6 94.3

Table 5

Total expenses, rub. rub.

2364 861

5.7 343 T of 3% of the amount of oxide oxide,% 15.5 4.1 0.3 No Table 4 I e-mouse,% Filtrate I Cake

Claims (2)

1. USSR author's certificate number 190024, cl. From 22 to 30/04, 1966. 2. Authors certificate of the USSR 155609, cl. From 22 to 7/02, 1967.