Arsenic removal method for crude antimony containing arsenic

Abstract

The present invention relates to the field of antimony smelting, and specifically discloses a method for removing arsenic from arsenic-containing crude antimony. The method comprises stirring and refining the arsenic-containing crude antimony and an iron-loaded composite material in a protective atmosphere at a temperature of 750 to 1000°C, causing As in the arsenic-containing crude antimony and iron in the iron-loaded composite material to undergo an alloying reaction and form a slag containing an FeAs alloy. The slag is then skimmed to obtain an arsenic-removed antimony melt. The iron-loaded composite material comprises a carrier and an immobilized iron element thereon; and the density thereof is less than 3 g / cm 3 The mass of iron in the iron-loaded composite material is 1 to 2 times the theoretical amount required to transform As into FeAs. The new arsenic removal method proposed by the present invention has good arsenic removal effect, simple operation, low raw material price, and good application value.

Description

Technical Field

[0001] The present invention relates to the technical field of crude antimony refining, in particular to the field of arsenic removal from arsenic-containing crude antimony. Background Art

[0002] Antimony is a crucial nonferrous metal widely used in the manufacture of fireproof materials, photovoltaic glass, lead-acid energy storage, and biopharmaceuticals. Due to the similar physical and chemical properties of arsenic and antimony, the raw material stibnite used in antimony smelting often contains significant amounts of arsenic. Crude antimony produced through pyrometallurgical and hydrometallurgical smelting often contains 0.3–3% arsenic. Arsenic is extremely toxic, so the antimony smelting industry places extremely high demands on the arsenic content of antimony. The resulting crude antimony requires further refining to meet the requirements of GB / T 1599-2014.

[0003] Currently, crude antimony refining primarily utilizes an oxidation refining process, which exploits the difference in oxygen affinity between arsenic and antimony. Soda ash or caustic soda flakes are added to the crude antimony as a slagging agent, and air acts as an oxidant to oxidize the arsenic in the crude antimony to form sodium arsenate, which then enters the refining slag, thereby removing arsenic from the crude antimony. However, this process converts arsenic into Na₃AsO₄. Since Na₃AsO₄ is highly soluble in water, improper handling can easily lead to soil and groundwater contamination in the smelter's area. Furthermore, while adding soda ash or caustic soda flakes as a slagging agent to crude antimony for oxidation refining to remove arsenic, a large amount of antimony is also oxidized and reacts with the soda ash or caustic soda flakes to form sodium antimonate. This Na₃SbO₄, Na₃AsO₄, and excess soda ash and caustic soda flakes form a highly toxic arsenic-alkali slag. The large-scale storage of arsenic-alkali slag poses a significant environmental risk. Furthermore, the sodium antimonate and other substances contained in it are difficult to recycle, resulting in a waste of resources and significant storage costs for antimony smelters.

[0004] Therefore, the industry urgently needs a method that is free of environmental burdens such as arsenic alkali slag hazardous waste and has excellent arsenic removal effect and selectivity. Summary of the Invention

[0005] In view of the problems that the existing arsenic removal process for arsenic-containing crude antimony has unsatisfactory arsenic removal effect and is prone to bring serious environmental pressure, the purpose of the present invention is to provide an arsenic removal method for arsenic-containing crude antimony, aiming to provide a harmless arsenic removal process with excellent arsenic removal effect and selectivity, and without environmental pressure such as arsenic alkali slag hazardous waste.

[0006] A method for removing arsenic from arsenic-containing crude antimony comprises stirring and refining the arsenic-containing crude antimony and an iron-loaded composite material in a protective atmosphere at a temperature of 750-1000°C to cause an alloying reaction between As in the arsenic-containing crude antimony and iron in the iron-loaded composite material to form a slag of an FeAs-loaded alloy (a general term for iron-arsenic alloys). The slag is then skimmed to obtain an arsenic-removed antimony melt.

[0007] The iron-loaded composite material comprises a carrier and an iron element immobilized thereon; the density of the carrier is less than 3 g / cm 3 ,

[0008] The mass of iron in the added iron-loaded composite material is 1 to 2 times the theoretical amount required to transform As into FeAs.

[0009] To address the selective arsenic removal problem in arsenic-containing crude antimony, the present invention is the first in the industry to propose a technical approach to arsenic removal from crude antimony based on Fe-As alloying. However, early in the development process, it was discovered that in order to successfully implement this new arsenic removal approach for the first time, many unique technical challenges needed to be overcome. For example, Fe can alloy with As, but it also alloys with Sb. Using iron for alloying arsenic removal requires resolving the issue of alloying selectivity with As and Sb. Furthermore, due to its unique properties, the Fe-As alloyed product cannot be separated from Sb with high selectivity, making true alloying arsenic removal impossible. To address the challenges of arsenic removal from crude antimony using the Fe-As alloying approach, the present invention, after in-depth research, innovatively pre-loads iron and further coordinates the combined control of temperature, specific gravity, and dosage during the refining process. This achieves synergy, effectively improving the arsenic removal efficiency and selectivity from crude antimony. Furthermore, it avoids environmental pressures such as the release of arsenic alkali slag and the release of high-risk H3As gas, meeting process application requirements.

[0010] In the present invention, there is no special requirement for the arsenic content in the arsenic-containing crude antimony. However, considering the excellent arsenic removal effect and environmental advantages of the process of the present invention, it can be applied to relatively high-content arsenic-containing crude antimony for industrial value considerations. For example, the arsenic content in the arsenic-containing crude antimony can be 0.01~10.0Wt.%, and further can be 1.5~5Wt.%.

[0011] In the present invention, the iron-loaded composite material can be realized based on known immobilization means, for example, the iron-loaded composite material is obtained by immobilizing an iron source on a carrier through chemical reduction or electrochemical reduction;

[0012] Preferably, the iron source is a ferrous iron and / or ferric iron compound;

[0013] Preferably, the carrier is at least one of porous carbon, zeolite, and diatomaceous earth.

[0014] In the present invention, the iron-containing composite material, the iron content is 5 to 35wt%, preferably 10 to 30wt.%;

[0015] Preferably, the particle size of the iron-loaded composite material is 1 to 5 mm;

[0016] Preferably, the density of the iron-loaded composite material is 1-2.5 g / cm 3 .

[0017] In the present invention, a melt containing arsenic and crude antimony can be obtained in advance, and then the iron-loaded composite material is added and refined at the temperature and protective atmosphere.

[0018] Preferably, the mass of iron in the added iron-loaded composite material is 1 to 1.5 times the theoretical amount required to transform As into FeAs.

[0019] In the present invention, the heating equipment in the refining stage is used to avoid introducing reactive gases into the reaction system as much as possible. For example, in the present invention, a particularly suitable heating equipment is an electric furnace.

[0020] In the present invention, the temperature in the refining stage is 750-900° C. Research in the present invention shows that refining at this temperature helps to further improve the selectivity of the reaction and helps to further improve the As removal effect and selectivity.

[0021] In the present invention, the protective atmosphere does not contain gases that can participate in the reaction, and is preferably at least one of nitrogen and inert gas.

[0022] In the present invention, the stirring method in the refining stage is gas stirring and / or mechanical stirring;

[0023] Preferably, the gas used for the gas agitation is a protective atmosphere;

[0024] Preferably, if gas agitation is used, the time for introducing gas into the reaction is 1 to 4 hours, and the gas flow rate is 2 to 5 m 3 / min into;

[0025] If mechanical stirring is used, the reaction time is 1.5~4 h and the melt rotation rate is 10~50 rpm.

[0026] In the present invention, after the stirring refining is completed, the melt is allowed to stand for 0.5 to 1 hour before slagging.

[0027] Beneficial effects

[0028] The process of this invention innovatively refines the iron-loaded composite material and arsenic-containing crude antimony, and further adjusts the parameters during the preparation process to selectively form FeAs alloys (e.g., FeAs, Fe2As, and Fe3As2 alloys), selectively reduce FeSb2, Fe3Sb2, and Fe-As-Sb reactions, and further facilitates the selective separation of slag and antimony liquid. This successfully achieves the efficient and highly selective removal of As from arsenic-containing crude antimony based on the Fe-As alloying principle, while avoiding the generation of waste, solid waste, and exhaust gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Process flow chart of the present invention DETAILED DESCRIPTION

[0030] The following examples are intended to further illustrate the present invention, but are not intended to limit the present invention.

[0031] In the following cases, the As content in the prime arsenic-containing crude antimony refers to the weight percentage.

[0032] This invention is the first in the industry to propose an idea for selectively removing arsenic from crude antimony based on FeAs alloying. Based on the technical problems that need to be overcome by this new idea, it provides improved means:

[0033] A typical arsenic removal method for arsenic-containing crude antimony according to the present invention involves directly adding an iron-loaded composite material to the crude antimony under an inert atmosphere. The melt is then stirred thoroughly using gas or mechanical stirring to form an FeAs alloy with the arsenic in the crude antimony and the iron in the composite material. After stirring, the melt is allowed to stand, allowing the resulting FeAs-loaded refined slag to float and separate from the crude antimony melt, achieving efficient arsenic removal from the crude antimony. The method specifically comprises the following steps:

[0034] (1) In an inert atmosphere, an iron-loaded composite material is added to a crude antimony melt, and then the melt pool is stirred to perform an arsenic removal reaction; the iron-loaded composite material has a particle size of 1 to 5 mm and a density of less than 3 g / cm 3 The mass of iron in the added iron-loaded composite material is 1-2 times the theoretical amount required to convert As into FeAs. The temperature for removing arsenic from crude antimony is 750-1000°C.

[0035] (2) After stirring the molten pool for a period of time, the melt is allowed to stand, and then the FeAs-loaded slag on the upper layer of the molten pool is removed to obtain the arsenic-removed antimony.

[0036] A typical embodiment of the present invention is that the iron-loaded composite material is obtained by adding one or a mixture of two of porous carbon, zeolite, and diatomaceous earth as a carrier to a ferrous solution, and chemically reducing or electrochemically reducing ferrous ions so that they are precipitated in the carrier particles to obtain the iron-loaded composite material.

[0037] In a typical embodiment of the present invention, the stirring of the melt in step (1) can be carried out by gas stirring or mechanical stirring. When gas stirring is adopted, the gas introduced can be nitrogen, argon or other inert gas that does not participate in the reaction.

[0038] A typical embodiment of the present invention is that if gas stirring is used in step (1), the time for introducing gas into the reaction is 1 to 4 hours, and the gas flow rate is 2 to 5 m 3 / min; if mechanical stirring is used, the reaction time is 1.5~4 h, and the melt rotation rate is 10~50 rpm.

[0039] In a typical embodiment of the present invention, after the reaction in step (2) is completed, the melt is allowed to stand for 0.5 to 1 h.

[0040] A typical embodiment of the present invention can be listed. The equipment adapted for this technical solution is an electric furnace.

[0041] Example 1

[0042] Porous carbon particles with a particle size of 1.5-2 mm were added to a 2.5 mol / L ferrous sulfate solution. Zinc powder (1.0 times the theoretical amount required to reduce all ferrous iron to elemental iron) was added to the ferrous sulfate solution and stirred at 80°C for a reduction reaction. After a period of reaction, the liquid and solid were separated, washed, dried, and sieved to obtain a product with an iron content of 30%, a particle size of 2 mm, and a density of 2.80 g / cm 3 Iron-loaded porous carbon particles. Using an electric furnace as the reaction equipment, 50 kg of the iron-loaded porous carbon particles were added to 1000 kg of molten crude antimony with an arsenic content of 1.81% at 800°C (refining temperature) in a nitrogen atmosphere. The melt was then stirred mechanically at 25 rpm for 2.5 hours. After stirring, the melt was allowed to stand for 0.5 hours to allow for stratification. The refining slag on the top of the melt was then scraped off.

[0043] After arsenic removal, analysis showed that the remaining mass of antimony was 968.33 kg, the arsenic content in antimony was 0.032%, and the direct recovery rate of antimony was 98.59%, meeting the arsenic content requirement for Sb 99.70 grade in GB / T 1599-2014.

[0044] Example 2

[0045] Zeolite particles with a particle size of 3-4 mm were added to a 2 mol / L ferrous chloride solution. Aluminum powder (1.2 times the theoretical amount required to reduce all ferrous iron to elemental iron) was added to the ferrous chloride solution and stirred at 50°C for a reduction reaction. After a period of reaction, the liquid and solid were separated, washed, dried, and sieved to obtain a zeolite with an iron content of 25%, a particle size of 4 mm, and a density of 2.41 g / cm 3 The iron-loaded zeolite particles were prepared by using an electric furnace as the reaction equipment. At 750 ° C and in an Ar atmosphere, 60 kg of the iron-loaded zeolite particles were added to 1000 kg of crude antimony melt with an arsenic content of 1.45%; then 3 m 3 Argon was introduced into the melt at a flow rate of 1 / min and the melt was fully stirred for 2 h. After the stirring was completed, the melt was allowed to stand for 0.5 h to allow the melt to separate into layers; then the refined slag on the upper layer of the melt was scraped off.

[0046] After arsenic removal, analysis showed that the remaining mass of antimony was 970.08 kg, the arsenic content in antimony was 0.041%, and the direct recovery rate of antimony was 98.39%, meeting the arsenic content requirement for Sb 99.70 grade in GB / T 1599-2014.

[0047] Example 3

[0048] Diatomaceous earth particles with a particle size of 0.5-1.0 mm were added to a 1.5 mol / L ferrous sulfate solution. Aluminum powder (1.0 times the theoretical amount required to reduce all ferrous iron to elemental iron) was added to the ferrous sulfate solution and stirred at 60°C for a reduction reaction. After a period of reaction, the liquid and solid were separated, washed, dried, and sieved to obtain a product with an iron content of 10%, a particle size of 1 mm, and a density of 2.65 g / cm 3 Using an electric furnace as the reaction equipment, 200 kg of the iron-loaded diatomite particles were added to 1000 kg of crude antimony melt with an arsenic content of 2.02% under a N2 atmosphere at 1000°C; then, 5 m 3 Nitrogen was introduced at a flow rate of 1000 N / min and the melt was fully stirred for 4 h. After the ventilation and stirring were completed, the melt was left to stand for 1 h to allow the melt to separate into layers; then the refined slag on the upper layer of the melt was scraped off.

[0049] After arsenic removal, analysis showed that the remaining mass of antimony was 936.80 kg, the arsenic content in antimony was 0.024%, and the direct recovery rate of antimony was 95.59%, which met the arsenic content requirement of Sb 99.70 grade in GB / T 1599-2014.

[0050] Example 4

[0051] In a 2.0 mol / L ferrous sulfate solution, diatomaceous earth and porous carbon particles with a particle size of 3-4 mm were added, wherein the weight ratio of diatomaceous earth to porous carbon particles was 1:1. The solution was mechanically stirred at the same time. Graphite was used as an electrode and the current density was 220 A / m 2 The electrochemical reduction treatment was carried out under the conditions of 35℃ and 18h ​​reaction, and the electrolyte was separated into liquid and solid, washed, dried and sieved to obtain a granular material with an iron content of 25%, a particle size of 5 mm and a density of 2.64 g / cm 3 A composite granular material of porous carbon and diatomite loaded with iron was prepared. Using an electric furnace as the reaction equipment, 100 kg of the composite granular material was added to 1000 kg of crude antimony melt with an arsenic content of 2.02% at 900°C in a nitrogen atmosphere. The melt was stirred mechanically at 50 rpm for 4 hours. After stirring, the melt was allowed to stand for 1 hour to allow for stratification. The refining slag on the top of the melt was then scraped off.

[0052] After arsenic removal, analysis showed that the remaining mass of antimony was 941.98 kg, the arsenic content in antimony was 0.025%, and the direct recovery rate of antimony was 96.12%, meeting the arsenic content requirement for Sb 99.70 grade in GB / T 1599-2014.

[0053] Comparative Example 1

[0054] The entire process is the same as Example 1, except that the refining temperature is 1100° C. The experimental results show that after arsenic removal, the remaining mass of antimony is 996.67 g, and the arsenic content in antimony is 1.76%, indicating poor arsenic removal effect.

[0055] Comparative Example 2

[0056] Compared with Example 1, the only difference was that the refining process temperature was 700°C. Experimental results showed that after arsenic removal, the remaining mass of antimony was 998.4 g, and the arsenic content in the antimony was 1.94%. The lack of a clear slag layer made it impossible to skim off the slag, resulting in poor arsenic removal.

[0057] Comparative Example 3 (composite material density is higher than 3 g / cm 3 )

[0058] Compared with Example 1, the only difference is that the composite material added to the crude antimony melt during the refining process has an iron content of 40%, a particle size greater than 6 mm, and a density of 3.86 g / cm 3 The amount of iron introduced is the same as in Example 1.

[0059] The experimental results show that after the arsenic removal is completed, no obvious slag layer is seen, which makes it impossible to remove the slag. The refined slag and the crude antimony melt are difficult to separate, and the arsenic cannot be removed.

[0060] Comparative Example 4

[0061] Compared with Example 1, the only difference is that a small reverberatory furnace is used as the refining equipment in the refining process.

[0062] The experimental results show that after arsenic removal, the remaining mass of antimony is 840.26 kg, the arsenic content in antimony is 0.88%, and the direct recovery rate of antimony is only 84.82%. The direct recovery rate of antimony is low and the arsenic removal effect is poor.

[0063] Comparative Example 4 uses a traditional reverberatory furnace as refining equipment. The reverberatory furnace provides heat by burning petrochemical energy. To ensure sufficient combustion of the fuel, an oxygen-enriched combustion oxygen supply method is usually adopted, which destroys the inert atmosphere of the alloying arsenic removal reaction. Part of the carbon in the composite material is oxidized, the floatability of the alloy phase deteriorates, and the arsenic removal effect deteriorates; antimony is partially oxidized to Sb2O3 and enters the flue gas, reducing the direct recovery rate of antimony.

[0064] Comparative Example 5 (Iron was not loaded onto the porous material through a reduction reaction, but directly mixed with the porous material and iron powder)

[0065] Compared with Example 1, the only difference is that the iron in the composite material added to the crude antimony melt during the refining process is not loaded onto the porous carbon through a reduction reaction, but is directly added to the crude antimony melt after mechanically mixing the porous carbon with iron powder (the weight of the introduced porous carbon and iron powder is the same as in Example 1).

[0066] The experimental results show that after the arsenic removal is completed, no obvious slag layer is seen, which makes it impossible to remove the slag. The refined slag and the crude antimony melt are difficult to separate, and the arsenic cannot be removed.

Claims

1. A method for removing arsenic from crude antimony containing arsenic, characterized in that: The arsenic-containing crude antimony and the iron-loaded composite material are stirred and refined in a protective atmosphere at a temperature of 750-1000°C to allow the As in the arsenic-containing crude antimony and the iron in the iron-loaded composite material to undergo an alloying reaction and form a slag loaded with FeAs alloy, which is then skimmed to obtain an arsenic-removed antimony melt. The iron-loaded composite material comprises a carrier and an iron element immobilized thereon; Its density is less than 3 g / cm 3 , The mass of iron in the added iron-loaded composite material is 1 to 2 times the theoretical amount required to transform As into FeAs.

2. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The arsenic content in the arsenic-containing crude antimony is 0.01-10.0 wt.%.

3. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The iron-loaded composite material is obtained by immobilizing an iron source on a carrier through chemical reduction or electrochemical reduction.

4. The method for removing arsenic from crude antimony containing arsenic according to claim 3, wherein: The iron source is a divalent iron and / or a trivalent iron compound.

5. The method for removing arsenic from crude antimony containing arsenic according to claim 3, wherein: The carrier is at least one of porous carbon, zeolite and diatomaceous earth.

6. The method for removing arsenic from crude antimony containing arsenic according to claim 3, wherein: The iron content in the iron-loaded composite material is 5-35 wt%.

7. The method for removing arsenic from crude antimony containing arsenic according to claim 6, wherein: The iron content in the iron-loaded composite material is 10-30 wt.%.

8. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The particle size of the iron-loaded composite material is 1-5 mm.

9. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The density of the iron-loaded composite material is 1-2.5 g / cm 3 .

10. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: A melt containing arsenic and crude antimony is obtained in advance, and then the iron-loaded composite material is added thereto, and refined at the temperature and under the protective atmosphere.

11. The method for removing arsenic from crude antimony containing arsenic according to claim 10, characterized in that: The mass of iron in the added iron-loaded composite material is 1 to 1.5 times the theoretical amount required to transform As into FeAs.

12. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The heating equipment in the refining stage is an electric furnace.

13. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The temperature in the refining stage is 750~900℃.

14. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The protective atmosphere does not contain gases that can participate in the reaction.

15. The method for removing arsenic from crude antimony containing arsenic according to claim 14, characterized in that: The protective atmosphere is at least one of nitrogen and inert gas.

16. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: The agitation method in the refining stage is gas agitation and / or mechanical agitation.

17. The method for removing arsenic from crude antimony containing arsenic according to claim 16, wherein: The gas used in the gas agitation is a protective atmosphere.

18. The method for removing arsenic from crude antimony containing arsenic according to claim 16, wherein: The reaction time of gas in the gas stirring process is 1~4 hours, and the gas flow rate is 2~5 m 3 / min into; The reaction time of mechanical stirring is 1.5~4 h, and the melt rotation rate is 10~50 rpm.

19. The method for removing arsenic from crude antimony containing arsenic according to claim 1, wherein: After the stirring refining is completed, the melt is allowed to stand for 0.5 to 1 hour before slagging.

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