SU916385A1 - Method for roasting pyrate concentrates - Google Patents

Description

The invention relates to methods for complex processing of pyrites or pyrite concentrate containing non-ferrous metals, namely, to the stage of burning with the extraction of sulfur in the gas phase with the transfer of non-ferrous metals to water-soluble sulfate form, and iron to oxide, and can be used in chemical technology and in color metallurgy.

The known method of burning pyrite with obtaining sulfur and sulfur dioxide in two stages, the first of which is carried out with a lack of oxygen at 700-800 * C, and the second with an excess of oxygen at 800-1000 ° C. This method involves the continuous calcination of pyrite, accompanied by the production of sulfur or sulfur and sulfur dioxide, in which gases containing sulfur dioxide from the calcination stage are passed through a layer of solid reducing agent and

2

fully or partially reduced to elemental sulfur, and the reduced gases are then passed

 through fresh pyrite at temperatures that allow you to ward off labile sulfur.

⁵ These stages are carried out in one unit, in which the contact of solid gas takes place in a fluidized bed. Roasting allows to obtain cinders suitable for use in the blast furnace.

⁰ S1TOdnako melting method can not be used when processing liritnyh concentrates and pyrites containing nonferrous metals, as no creases ¹⁵ D retrieval problem.

Closest to the proposed technical essence and the achieved result is a method of burning pyrite concentrates in fluidized bed furnaces. In the process of testing during the roasting of pyrite concentrate in a KS-TsV furnace with a blast enriched with oxygen up to 36.5%. is achieved

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productivity 8 t / m ^ per day with high quality of the obtained calcine. Kiln gases contain 18–20% sulfur dioxide and about 5% oxygen. On air blowing pro, productivity 4 t / m ^2- per day, roasting gases contain 7-8% of sulfur dioxide and 7 "8% of oxygen £ 2 ^.

However, the known method is characterized by an insufficiently high firing productivity, a low degree of use of oxygen (at an air blast, it is 6070%), and as a result, a low concentration of sulfur dioxide in the firing gases.

The purpose of the invention is to improve the performance of roasting, the degree of use of oxygen, increasing the concentration of sulfur dioxide in the calcining gas, cheaper gas cleaning from dust, increasing the degree of sulfatization of non-ferrous metals.

This goal is achieved by the fact that the pyrite concentrate containing non-ferrous metals is subjected to two stage firing, while the first stage is carried out with a lack of oxygen at a weight ratio of sulfur: oxygen equal to 1: O, 3 “O, 6, second

. the stage is carried out with an excess of oxygen at a weight ratio of sulfur'.oxygen equal to 1: 1.8-3.5, then the gas of the first firing stage is combined with the gas of the second firing stage for co-processing.

In the first firing step maintained at 650-850 ° C and in the second - S. 610-720 ^minutes

Table 1

The weight ratio of sulfur in the charge to oxygen in the blast The composition of the firing gases,% 50 _g | | $ 2 1: 0.3 19-20 5-7 0.1-0.5 1: 0.4 19-20 four 0.1-0.5 1: 0.5 19-20 0,6- 0.1-0.5 ' 1: 0.6 19-20 0.0 0.1-0.5

Pyrrhotinized cinder enters the second firing stage, which is carried out with the ratio of oxygen consumption to the stoichiometric one (theoretically, the first firing stage is oxygen ₍ oxygen is supplied in an amount sufficient to oxidize part of the sulfur concentrate) 3 "0,6). An increase in the amount of oxygen in the blast is higher than the sulfur: oxygen ratio of 1: O is impractical because it decreases

10 content of elemental hera in gases. Reducing the amount of oxygen is less than the 1: 0.3 ratio leads to a decrease in the specific productivity of the process. Lack of oxygen

15 in the blast at the first stage of firing provides a high degree of its use (at least 98%).

The temperature of the firing process in the first stage is inappropriate to increase above 850-900®С, as this results in a coarsening of the material, which leads to disruption of the process. Lowering the temperature contributes to the content of the gases obzhi25 govyh elemental sulfur, but lowering the temperature below 65O ^Q C is impractical because it dramatically decreases the process performance.

The temperature in the bed is controlled by changing the loading rate of pyrites or pyrite concentrate without the use of heat exchangers. The products of the first firing stage are pyrrhotinized calcine and gases.

The composition of the kiln gases produced by the use of air ’blasting is given in table. one.

According to the reaction 2Pe5 + 3, BO ^ Pe ^ O ^ -L ⁵⁵ -250 ^ + · О, 1, 25 ^- 2.0, with the ratio of the amount of sulfur in the feed to the amount of oxygen in the blast 1 / 1.81 / 3.5. When oxidizing sulfatizuyu5

An optimal ratio of sulfur: oxygen is 1 / 3-1 / 3 when calcined in furnaces of a fluidized bed with two successively set return cyclones (KS-TsV furnace of the NIUIF design). Sulfur: oxygen can be reduced to 1/1 , 8-1 / 1.9 ·

The firing process in the second stage is carried out at 610-720 * 0. Lowering the firing temperature below 61O ^% C significantly reduces the productivity of the process, increases the degree of sulfatization of iron, which leads to insufficient separation of iron and

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non-ferrous metals at the leaching stage of the calcine. An increase in temperature above 720 ^e С leads to a decrease in the degree of sulfatization of nonferrous metals.

The enrichment of the blast with oxygen increases the specific productivity of the process, the degree of sulfatization of Yu non-ferrous metals, and the concentration of waste gases on sulfurous anhydride. The products of the second firing stage are the calcine and firing gases.

The composition of the calcined gases of the second stage of the 15th diy is given in Table. 2

•Table 2

Weight Contains relationship acidity Tempera sulfur reduction kind of in tour, in download tye,% ° С ke ke breed in Blowing

The composition of the firing gases,%

50 _o

Degree of sulfatization

Os

50 _i

Colored

metals

Iron

1: 3 34 7yu 12 14 2.5 92-97 0.1-0.2 1: 3 34 730 12 14 2.5 90-92 0.1-0.2 • 1: 3 34 690 12 14 2.5 92-97 0.2-0.3 1: 3 21 690 6.5 7 2.0 90-94 0.2-0.3 1: 3 21 650 6.0 7 1.8 85-92 0.3-0.5 1: 3,5 21 690 6.0 8.0 2.0 90-94 Oh, 1st, ’ 1: 4 21 650 5.5 7.5 1.8 85-92 0.3-0.5 1: 2 21 650 7.5 5.5 1.5 85-88 0.3-0.5 1: 3 21 610 6.0 7.0 1.5 85-88 5-1 o 1: 2.5 21 650 6.7 6.3 1.5 85-90 0.3-0.5

Gases of the first and third stages of firing are combined for joint processing

four......... . _. Weight ratio Content Weight Content sulfur sulfur in oxygen an attitude oxygen loading to acid in the blast sulfur in in the blast on rock in the blast on the T-th stage load to C-th Stage at stage 1 ~ diya % oxygen di,% on dd ! stages

The amount of calcining gas · call,%, with

two-stage roasting

50,

bots. The composition of the combined calcined gases is given in table. 3

Table 3

1: 0.5

1: 0.4

21

21

1: 3 34 18.0 9

1: 3 34 18.5 7.3

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Continued table. 3

sulfur ratio c. loading to oxygen in the blast at the 1st stage The oxygen content in the blast at the 1st stage,% The weight ratio of sulfur in the load to oxygen at the C-th stage The oxygen content in the blast at ί 1st stage,% The composition of the kiln gases,%, with two-stage roasting 50 _g at ⁴ 1: 0.5 21 1: 3 34 18.6 5.6 1: 0.6 21 1: 3 21 15 3.0 1: 0.3 21 1: 3 21 12.3 6.1 1: 0.4 21 1: 3 ²¹ 13.1 5.2 1: 0.5 21 1: 3 21 14.0 4.2 1: 0.6 21 1: 4 21 13.1 5.2. 1: 0.6 21 1: 2 2T 17.4 0

As can be seen from the data table. 3, in a two-stage roasting, the content of sulfuric anhydride in gases is much higher than its content in one-stage roasting.

Example. Two-stage roasting of pyrite and pyrite concentrate.

A semi-industrial test of the first firing stage was carried out under the following mode: layer temperature 700750 * С, weight ratio of sulfur in feed to oxygen in blast '1: 0.5 · Capacity is more than 30 t / m ^2, per day. The resulting gases contain 19 ~ 20% 50 ^, 0.1-0.5% (¾. And 40 to 2% elemental sulfur.

The pyrrhotinized cinder obtained in tests of the 1st stage of burning is directed to the ΧΙth stage of burning, the pilot industrial tests of which are carried out in a KS-TsV furnace (fluidized bed with two successively set return cyclones) -65O ^LS , the weight ratio of sulfur in the feed to oxygen blast is 1: 2.5. The specific productivity of this stage of burning in the air blast is 6 t / m ¹ per day, the burning gases contain 6-7% 5¾. 7-8% 0 _g and 1.5% 50h,

The total productivity of the roasting of both stages 6,3 "6,5 t / N ^2-

²⁵ per day in pyrite concentrate, combined gases contain 11.5 "

12% 50 & and 4.0-5.0% 0%.

When a one-stage calcination of a pyrite concentrate in a KS-TsV furnace under air blast is carried out under the same conditions, the following indicators are obtained: the specific productivity of the pyrite concentrate is 4 t / m ^g 'per day, the burning gases contain 7-8% 50 ^

35 and 7 ”8% 0 £.

Extraction of non-ferrous metals in a single-stage and two-stage process is at the same level.

Compared with the known methods, the proposed one and a half will reduce the consumption of the blast, which reduces capital and operating costs for the blower economy. At the same time, the volume of waste gases is reduced by one and a half times, which will reduce the amount and amount of equipment and operating costs for cleaning the exhaust gases from dust. An increase in roasting performance of 1.6 times will reduce the number of kilns, which will reduce the cost of investment.

The proposed method allows you to organize the process so that even on an air blast to get gases, suitable for extracting from them not only sulfuric acid, but elemental sulfur. Pilot Industrial

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tests show high abilities

process reliability.

Claims (2)

Claim 5 1. The method of burning pyrite concentrates containing non-ferrous metals using an oxygen-containing blast with subsequent processing of the resulting sulfur dioxide, characterized in that, in order to increase the concentration of sulfur dioxide in the calcining gas, the degree of oxygen and increase productivity, burning is in two stages, the first of which is carried out by the lack of oxygen at a ratio of sulfur: oxygen equal to 1: 0.3 ”0.6, and the second with an excess of oxygen at a ratio of sulfur: oxygen equal to 1: 1.83.5, and then gas first burning step is combined with the gas produced after a second burning step of co-processing. 2. The way pop. 1, characterized in that at the first stage of firing the temperature is maintained at 650-850 ^ 0, and at the second - 61О-72О * ^? WITH.