WO2019210533A1 - Harmless disposal method for cyanidation tailing - Google Patents

Abstract

A harmless disposal method for a cyanidation tailing, performed according to the following steps: (1) preparing the cyanidation tailing as a raw material, or adding an additive CaO to the cyanidation tailing as a mixed raw material; (2) heating the raw material or the mixed raw material to 250-450°C for pyrolysis and carrying out thermal insulation for less than or equal to 90 min so as to obtain calcine; and (3) directly using the calcine for backfill treatment, or extracting pyrite by means of flotation. The method has a good cyanogen removal effect, and the cyanidation tailing after undergoing low-temperature pyrolysis meets requirements of common solid wastes.

Description

Harmless treatment method for cyanide tailings Technical field

The invention belongs to a method for treating pollutants in the field of non-ferrous metal metallurgy and environmental protection, and particularly relates to a method for harmless treatment of cyanide tailings.

Background technique

Because gold mines use cyanide gold extraction technology in the production process, a large amount of cyanide tailings are produced. These cyanide tailings contain a large amount of pollutants such as sulfur, copper, arsenic, mercury and highly toxic cyanide. In addition to the small amount of cyanide tailings that can be utilized, a considerable amount of cyanide tailings is only stored or directly landfilled, which not only occupies a large amount of land resources, but also has hidden dangers of polluting surface water, groundwater and soil. It has great potential safety hazards and environmental hazards to the surrounding environment. At present, cyanide tailings have been listed as HW33 hazardous wastes in the National Hazardous Waste List by the state. The pollution characteristics are obvious and the pollution is serious. The environmental pressure of the state and enterprises The surge has been urgently needed to adopt practical control techniques to eliminate the environmental hazards of such hazardous wastes.

At present, the technology for treating cyanide tailings is mainly flotation, supplemented by autoclaving, chlorination roasting, molten salt roasting, reduction roasting, oxidation, solidification, preparation of Portland cement, etc. ; flotation (CN201410228170.5, CN201410099597.X, CN201510055236.X) and more under weakly acidic conditions, under these conditions, CN ^- unstable, resulting in poor working conditions, and it must be repeated flotation; autoclave method (CN201510023812.2) is mainly carried out in autoclave or autoclave, it takes a long time to maintain pressure at high temperature, and needs to deal with secondary pollution caused by autoclaving; chlorination roasting method (CN201410317041.3, CN201410757942.4) is mainly The method of mixing chlorinating agent and the cyanide tailings with high-temperature roasting has higher requirements on equipment anti-corrosion ability and higher energy consumption; molten salt roasting method (CN201410317042.8, CN201611121854.0) adopts molten salt or molten pool to cyanide The slag is calcined, the calcination temperature is higher, and the time is longer; the reduction roasting method (CN201610825331.8, CN201610846576.9) uses a reducing agent to reduce at a high temperature, and the reduction time is longer; the oxidation method (CN201711048319.1) uses ozone and hydrogen peroxide. Sodium hypochlorite The oxidant oxidizes the cyanide tailings, and the operation cost is high; the curing method (CN201710628397.2) uses a curing agent to solidify the cyanide slag, but cannot fundamentally solve the environmental pollution caused by the cyanide tailings; (CN201210002870.3, Kong Yapeng. Comprehensive utilization of valuable elements in cyanide tailings [D]. Northeastern University), using ordinary cyanide tailings with high aluminum and silicon content to prepare ordinary Portland cement; these existing methods Or high energy consumption or secondary pollution or incomplete cyanide or complex process, high operating costs; therefore, for cyanide tailings, there is currently no economic and effective treatment of this type of hazardous waste. .

Summary of the invention

In view of the above-mentioned deficiencies in the current cyanide tailings technology, the present invention provides a harmless treatment method for cyanide tailings. After low temperature pyrolysis, the calcining sand is directly used in mining enterprises for backfilling or flotation to separate high grades. Pyrite, simplifying the process and reducing pollution.

The method of the invention comprises the following steps:

1. Preparing cyanide tailings as a raw material, or adding additive CaO to the cyanidation tailings as a mixed raw material; wherein the CaO is added in a molar ratio of CaO to the S element in the cyanide tailings of 0 to 1;

2, the raw materials or mixed raw materials are heated to 250 ~ 450 ° C for pyrolysis, to 250 ~ 450 ° C holding time ≤ 90min to complete the pyrolysis, the cyanide is removed, to obtain the baking sand;

3. The calcine is directly used for backfilling treatment or flotation to extract pyrite.

In the above method, the method for flotation flotation extraction of pyrite is: adding calcined water to a slurry having a mass concentration of 5 to 35%; adding a flotation agent xanthate, a foaming agent and an inhibitor to the slurry, and then Flotation; wherein the amount of xanthate added is (0.5-6)×10 ^-5 mol/L in the pulp, and the foaming agent is added in the concentration of the foaming agent in the pulp. 100mg / L, the inhibitor is added in an amount of 10 ~ 100g / t calcine; the foaming agent is 2 # oil or methyl isobutyl methanol, the inhibitor is water glass, sodium hexametaphosphate, fluorine Sodium silicate or carboxymethyl cellulose; flotation temperature is 15 ~ 80 ° C, time is 0.5 ~ 20min, flotation concentrate and flotation tailings are obtained; the mass percentage of the flotation concentrate is pressure filtered to water is 10 ~20%, get yellow iron ore.

The flotation tailings described above are landfilled.

The cyanide tailings are all mud cyanide tailings produced by the cyanidation gold extraction process, direct cyanidation tailings of flotation concentrate, bio-oxidation cyanide residue or roasting cyanide tailings.

The solid content of the cyanide tailings mentioned above is 10 to 45% by mass of Fe, S 2 to 51%, 4 to 55% of SiO ₂ , 1 to 10% of Al ₂ O ₃ , 0.4 to 5% of CaO, and CN ^- The content is 50 to 2500 mg/kg.

In the above method, the atmosphere at the time of pyrolysis is an air atmosphere.

The solid content of the above pyrite material has a sulfur content of more than 45% and an iron content of more than 39%.

The invention has the beneficial effects that the cyanide tailings can be cleanly transformed by the low temperature weak oxidizing atmosphere, and the cyanide removal rate is better than 99%; the additive CaO can fix the sulfide and partial cyanide in the cyanide tailings, Avoid contamination of the environment during pyrolysis; low temperature pyrolysis cyanide has no relationship with the initial concentration of cyanide, and is related to time and temperature. The cyanide tailings after low temperature pyrolysis meet the requirements of ordinary solid waste, which can be based on tailings composition and site conditions. It is selected for mine backfilling or reuse as secondary resource of sulfur concentrate; high grade pyrite can be obtained by flotation; tailings after flotation are selected for backfilling or other treatment according to flotation process.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the flow of a method for detoxifying a cyanide tailings of the present invention.

detailed description

The cyanidation tailings used in the examples of the present invention are all mud cyanidation tailings produced by the cyanidation gold extraction process, direct cyanidation tailings of flotation concentrate, bio-oxidation cyanide residue or roasting cyanide tailings.

The whole mud cyanidation tailings or the flotation concentrate of the cyanide tailings in the embodiment of the present invention is an aqueous cyanide tailings formed by pressure filtration to a water content of <30%, and with the continuation of the stacking time, The water content is gradually reduced; uncracked cyanide tailings and cyanide tailings stacked at different times can be used as raw materials.

In the embodiment of the invention, the cyanide removal rate is ≥99%.

In the embodiment of the present invention, the temperature rise rate is controlled to be 5 to 20 ° C / min when pyrolysis is performed.

The xanthate, 2# oil, methyl isobutyl alcohol, water glass, sodium hexametaphosphate, sodium fluorosilicate and carboxymethyl cellulose used in the examples of the present invention are commercially available industrial products.

The apparatus used in the low temperature pyrolysis in the embodiment of the present invention is a rotary kiln.

In the embodiment of the invention, the mass content of sulfur in the solid component of the pyrite material exceeds 45%, and the mass content of iron exceeds 39%.

The atmosphere at the time of pyrolysis in the embodiment of the present invention is an air atmosphere.

The technical solutions of the present invention are further described in the following with reference to the preferred embodiments. The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

Example 1

The cyanide tailings are cyanide tailings produced by a company in Shandong. The mass percentage of water is 12.4%. The solid content contains Fe 41.41%, S 48.40%, SiO ₂ 5.72%, Al ₂ O ₃ 1.48%. , CaO 0.47%, CN ^- content 340mg / kg;

Preparing cyanide tailings as raw materials;

The raw material is heated to 250 ° C for pyrolysis, after reaching 250 ° C and then kept warm for 90 min to complete pyrolysis, the cyanide is removed, and the calcine is obtained;

The calcine is directly used for backfilling;

After testing found, total cyanide tailings cyanide (to CN ^- basis) gradually becomes small at the end of the pyrolysis, the pyrolysis of material is substantially free of cyanide, CN ^- almost zero, cyano break rate of more than 99% .

Example 2

The method is the same as that in Embodiment 1, except that:

(1) The mass percentage of water in cyanide tailings is 16.9%, and the solid content contains Fe 29.92%, S 33.30%, SiO ₂ 24.95%, Al ₂ O ₃ 5.25%, CaO 1.15%, CN ^- content 500 mg. /kg;

(2) The raw material is heated to 350 ° C for pyrolysis, and after 350 ° C, the thermal solution is completed for 15 min;

(3) adding calcined water to make a slurry with a mass concentration of 35%; adding flotation agent xanthate, foaming agent and inhibitor to the slurry, and then performing flotation; wherein the amount of xanthate added is in the pulp according to xanthate a concentration of 0.5 × 10 ^-5 mol / L, the amount of blowing agent added by the foaming agent concentration in the pulp was 100mg / L, the amount of inhibitor is added to 100g / t calcine; the foaming agent For 2# oil, the inhibitor is water glass; the flotation temperature is 15 ° C, the time is 20 min, the flotation concentrate and the flotation tailings are obtained; the mass percentage of the flotation concentrate is filtered to water is 10 %, get the yellow iron ore material.

Example 3

The method is the same as that in Embodiment 1, except that:

(1) The mass percentage of water in cyanide tailings is 23.7%, and the solid content contains Fe 29.92%, S 33.30%, SiO ₂ 24.95%, Al ₂ O ₃ 5.25%, CaO 1.15%, CN ^- content 1160 mg. /kg;

(2) The raw material is heated to 450 ° C for pyrolysis, and after reaching 450 ° C, the pyrolysis is completed.

Example 4

The method is the same as that in Embodiment 1, except that:

(1) The mass percentage of water in the cyanidation tailings is 8.31%;

(2) adding the additive CaO to the cyanide tailings as a mixed raw material; wherein the CaO is added in a molar ratio of CaO to the S element in the cyanide tailings of 0.3;

(3) heating the mixed raw material to 300 ° C for pyrolysis, after reaching 300 ° C and then holding for 30 min to complete pyrolysis;

(4) adding calcined water to make pulp with a mass concentration of 20%; adding flotation agent xanthate, foaming agent and inhibitor to the slurry, and then performing flotation; wherein the amount of xanthate added is in the pulp according to xanthate The concentration is 2×10 ^-5 mol/L, the foaming agent is added in an amount of 200 mg/L in the pulp, and the inhibitor is added in a calcining amount of 40 g/t; the foaming agent; Is methyl isobutyl alcohol, the inhibitor is sodium hexametaphosphate; the flotation temperature is 30 ° C, the time is 3 min, the flotation concentrate and flotation tailings are obtained; the flotation concentrate is pressure filtered to water The mass percentage is 15% and the pyrite material is obtained.

Example 5

The method is the same as that of Embodiment 2, and the difference lies in:

(1) The mass percentage of water in the cyanidation tailings is 23.7%;

(2) adding additive CaO to the cyanide tailings as a mixed raw material; wherein the CaO is added in a molar ratio of CaO to the S element in the cyanide tailings of 0.6;

(3) The mixed raw materials are heated to 400 ° C for pyrolysis, and after reaching 400 ° C for 2 min, the pyrolysis is completed.

Example 6

The method is the same as that of Embodiment 3, and the difference lies in:

(1) The mass percentage of water in the cyanidation tailings is 5.6%;

(2) adding the additive CaO to the cyanide tailings as a mixed raw material; wherein the CaO is added in a molar ratio of CaO to the S element in the cyanide tailings of 1;

(3) heating the mixed raw material to 450 ° C for pyrolysis, after reaching 450 ° C to complete pyrolysis;

(4) Adding calcine to water to make a slurry with a mass concentration of 5%; adding flotation agent xanthate and inhibitor to the slurry, and then performing flotation; wherein the amount of xanthate added is 6 in the pulp. ×10 ^-5 mol/L, the inhibitor is added in an amount of 10 g/t calcine; the inhibitor is sodium fluorosilicate; the flotation temperature is 80 ° C, the time is 0.5 min, and the flotation concentrate and float are obtained. The tailings are selected; the mass percentage of the flotation concentrate is filtered to water by 20% to obtain the pyrite.

Example 7

The method is the same as that of Embodiment 2, and the difference lies in:

(1) The mass percentage of water in the cyanidation tailings is 20.9%;

(2) adding additive CaO to the cyanide tailings as a mixed raw material; wherein the CaO is added in a molar ratio of CaO to the S element in the cyanide tailings of 0.5;

(3) The mixed raw materials were heated to 420 ° C for pyrolysis, and after 420 ° C, the thermal solution was completed by holding for 1 min.

Example 8

The method is the same as that of Embodiment 3, and the difference lies in:

(1) The mass percentage of water in the cyanidation tailings is 8.2%;

(2) adding additive CaO to the cyanide tailings as a mixed raw material; wherein the CaO is added in a molar ratio of CaO to the S element in the cyanide tailings of 0.8;

(3) heating the mixed raw material to 450 ° C for pyrolysis, after reaching 450 ° C to complete pyrolysis;

(4) adding calcine to water to make a slurry with a mass concentration of 13%; adding flotation agent xanthate and inhibitor to the slurry, and then performing flotation; wherein the amount of xanthate added is 6 in the pulp. ×10 ^-5 mol/L, the inhibitor is added in an amount of 10 g/t of calcine; the inhibitor is carboxymethylcellulose; the flotation temperature is 85 ° C, the time is 0.5 min, and the flotation concentrate is obtained. Flotation tailings; the flotation concentrate is pressure filtered to a water mass percentage of 150% to obtain pyrite.

Claims (4)

A method for harmless treatment of cyanide tailings, which is characterized by the following steps: (1) preparing cyanide tailings as a raw material, or adding additive CaO to the cyanide tailings as a mixed raw material; wherein the CaO is added in a molar ratio of CaO to the S element in the cyanide tailings of 0 to 1; (2) heating the raw material or the mixed raw material to 250-450 ° C for pyrolysis, achieving a thermal decomposition time of 250-450 ° C holding time ≤ 90 min, and removing cyanide to obtain a baking sand; (3) The calcine is directly used for backfilling treatment, or flotation is used to extract pyrite. The method for detoxifying cyanidation tailings according to claim 1, characterized in that the method for flotation flotation and extraction of pyrite is: adding calcined water to a mass concentration of 5 to 35 % of pulp; adding flotation agent xanthate, foaming agent and inhibitor to the slurry, and then performing flotation; wherein the amount of xanthate added is (0.5-6)×10 ^-5 according to the concentration of xanthate in the pulp. Moll/L, the foaming agent is added in an amount of 0 to 100 mg/L in the pulp, and the inhibitor is added in an amount of 10 to 100 g/t. The foaming agent is 2# oil. Or methyl isobutyl alcohol, the inhibitor is water glass, sodium hexametaphosphate, sodium fluorosilicate or carboxymethyl cellulose; flotation temperature is 15 ~ 80 ° C, time is 0.5 ~ 20min, obtaining flotation Concentrate and flotation tailings; the mass percentage of the flotation concentrate to the water is 10-20%, and the pyrite material is obtained. The method for detoxifying a cyanide tailings according to claim 1, wherein the cyanide tailings have a solid content of 10 to 45% by mass, S 2 to 51% by mass of SiO. _{2 4 ~ 55%, Al 2} O 3 1 ~ 10%, CaO 0.4 ~ 5%, and CN ^- content of 50 ~ 2500mg / kg. The method for detoxifying a cyanide tailings according to claim 1, wherein the atmosphere during pyrolysis in the step (2) is an air atmosphere.

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