Method for comprehensively recycling high and low boiling residues and waste acid in production process of high-purity antimony

Abstract

The invention discloses a method for comprehensively recycling high and low boiling residues and waste acid in the production process of high-purity antimony, and relates to the field of non-ferrous metal metallurgy. The method comprises the following steps: mixing high and low boiling residues produced in the preparation process of high-purity antimony with waste acid produced by cleaning equipment, spraying the mixed solution into a roasting tower through compressed air for roasting, and enabling roasted flue gas to sequentially pass through a settling chamber, a bag collector and a two-stage water spraying absorption tower to respectively produce antimony white and hydrochloric acid, the produced antimony white can be directly sold or used as an antimony smelting raw material, and the byproduct hydrochloric acid can be used as an acid for wet smelting or can be further concentrated into 35-38% concentrated hydrochloric acid. The method can realize gradient recycling of antimony and chlorine elements in the high and low boiling residues and the waste acid, has the characteristics of high resource utilization level and no generation of a large amount of wastewater, and has good economic value and environmental protection benefit.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal hydrometallurgy and comprehensive utilization of secondary resources, specifically relating to a method for the comprehensive recovery and resource utilization of by-products generated during the chemical production of high-purity antimony—high and low boiling points and cleaning waste acid. Background Technology

[0002] High-purity antimony (purity ≥5N) is a key material in high-tech fields such as infrared detectors and semiconductor substrates. Currently, the large-scale production of high-purity antimony mainly adopts chemical methods, with core processes including chlorination of antimony raw materials, multi-stage distillation purification, and hydrogen reduction. During this process, the distillation step generates a certain amount of low-boiling-point and high-boiling-point impurity fractions (collectively referred to as high- and low-boiling substances), the main component of which is antimony trichloride (SbCl3), and contains small amounts of impurities such as arsenic. Simultaneously, during the start-up, shutdown, and maintenance of the production unit, equipment such as the distillation column and reaction vessel need to be cleaned, resulting in waste acid containing hydrochloric acid (HCl) and dissolved antimony salts.

[0003] Currently, the mainstream treatment method for these two types of waste in the industry is separate disposal, forming an inherent technological path dependence. For high- and low-boiling-point substances, hydrolysis is usually used, which involves adding water to produce antimony oxychloride (SbOCl) precipitate. Antimony oxychloride is sold as a low-value intermediate product. However, the hydrolysis process itself generates a large amount of acidic wastewater rich in hydrochloric acid and antimony salts, requiring complex subsequent neutralization treatment. For cleaning waste acid, the common method is direct neutralization with alkaline solution, neutralizing the acid before discharge. The chlorine element is not only not utilized, but is also converted into chloride ions in the wastewater, increasing the environmental burden.

[0004] While the aforementioned existing technical solutions are relatively simple to operate, they suffer from significant structural flaws: First, resource recovery is incomplete and of low value. Antimony is only recovered as antimony oxychloride, requiring further processing by downstream manufacturers to convert it into metallic antimony or antimony oxide, resulting in poor economic efficiency; chlorine is completely not recovered and is lost with wastewater. Second, environmental pollution is significant. Both hydrolysis and neutralization inevitably generate large amounts of saline or acidic wastewater requiring treatment, leading to high treatment costs and significant environmental risks. Third, the process essentially generates more waste from waste, failing to achieve true clean production and resource recycling.

[0005] When faced with the aforementioned problems, those skilled in the art typically optimize existing technologies, such as seeking higher-value utilization methods for antimony oxychloride, improving hydrolysis processes to reduce wastewater, or evaporating and concentrating waste acid. These approaches fail to break free from the traditional mindset and technical framework of treating the two wastes as independent problems and treating them separately. Therefore, the industry has long lacked a fundamental technical solution that simultaneously addresses the contradiction between the high-value recovery of antimony and chlorine resources and the large-scale generation of wastewater. Developing a novel clean production technology capable of synergistically treating both wastes, achieving full recovery of valuable elements, and near-zero wastewater discharge has become an urgent technical challenge in this field, and is of great significance for enhancing the sustainable development capabilities of the entire high-purity antimony industry. Summary of the Invention

[0006] The purpose of this invention is to completely overcome the structural defects of existing technologies, such as low resource recovery rate, poor product value, and serious secondary pollution, and to provide a novel, synergistic, resource-efficient, and environmentally friendly method for the comprehensive recycling and utilization of high and low boiling points and waste acids.

[0007] To achieve the above objectives, this invention abandons the traditional approach of treating the two wastes separately and creatively proposes a novel technical concept of combining them into one for synergistic transformation. Its core lies in mixing high- and low-boiling-point substances containing antimony trichloride with cleaning waste acid containing hydrochloric acid in a specific ratio to form a new reaction system. Then, using the highly efficient method of atomized roasting, the mixture instantly completes a series of coupled reactions at high temperature, directly converting the antimony and chlorine in the waste into high-purity antimony white product and industrial hydrochloric acid, respectively, thus eliminating wastewater generation at the source.

[0008] The technical solution of this invention is as follows: a method for the comprehensive recovery and utilization of high and low boiling points and waste acid in the production process of high-purity antimony, comprising the following steps: (1) Mixing: The high- and low-boiling-point substances produced during the production of high-purity antimony are mixed with the waste acid produced from the cleaning tower equipment. This step is the key starting point of this invention, which breaks the traditional separate-construction mode and creates a new reaction precursor. The volume mixing ratio of the high- and low-boiling-point substances to the waste acid is 1:0.3 to 1. This ratio range can ensure the balance of water and hydrogen chloride in the subsequent roasting reaction, which not only ensures the full hydrolysis and oxidation of antimony trichloride, but also creates conditions for the volatilization and capture of hydrogen chloride. The mixing time is controlled at 0.5 to 1 hour to ensure that the two are fully contacted and homogenized. (2) Calcination: The mixed solution obtained in step (1) is sprayed into the calcination tower through an atomizing nozzle. The atomization process greatly increases the specific surface area of ​​the droplets, enabling the mixed droplets to undergo instantaneous and complete thermal decomposition and oxidation reactions in the high-temperature environment inside the tower. The calcination temperature is strictly controlled between 500℃ and 700℃. This temperature window can ensure that antimony trichloride is completely decomposed into antimony oxide, and can also avoid excessive volatilization or sintering of antimony oxide. A slight negative pressure of -50 to -100 Pa is maintained inside the calcination tower to prevent the leakage of harmful gases and ensure smooth gas flow in the reaction. The inlet pressure of the mixed solution is preferably 0.1 to 0.3 MPa, and the pressure of the atomizing compressed air is preferably 0.3 to 0.6 MPa. The calcination tower can be heated by electricity, natural gas, or water gas. (3) Collection: The high-temperature flue gas generated during roasting mainly contains antimony oxide (Sb2O3) dust, gaseous hydrogen chloride (HCl), and water vapor. This flue gas first enters the settling chamber, where coarse antimony white particles are initially removed by gravity settling. The inlet temperature of the settling chamber is controlled at 300-350℃, and the outlet temperature is reduced to 120-150℃. This temperature gradient design ensures that the antimony white particles settle effectively in solid form and prevents corrosive gases from condensing due to excessively low temperatures. The settling chamber is preferably made of 316L stainless steel, which is resistant to chloride ion corrosion. Subsequently, the flue gas enters the bag filter dust collector to finely capture the remaining fine antimony white particles. The inlet temperature of the bag filter dust collector is controlled at 120-150℃, and the outlet temperature is 100-120℃ to maintain it above the acid dew point, preventing equipment corrosion and filter bag caking. The solid products collected from the settling chamber and the bag filter dust collector are combined to form a high-purity antimony white product.

[0009] (4) Absorption: The exhaust gas after dust removal by the bag filter mainly consists of hydrogen chloride and a small amount of water vapor. This exhaust gas enters a two-stage water spray absorption tower connected in series, where hydrogen chloride is absorbed by water in a counter-current contact to generate hydrochloric acid. By controlling the spray water volume and the number of stages, a by-product hydrochloric acid concentration of 18% to 22% can be obtained. To further ensure that the exhaust gas fully meets emission standards, the gas after two-stage water absorption finally enters an alkaline absorption tower (e.g., using sodium hydroxide solution spraying) to neutralize the residual trace amounts of acidic gas. The purified gas is then discharged into the atmosphere through a chimney.

[0010] The inventive mechanism and synergistic effect of the technical solution of this invention: The core reaction mechanism of this invention is as follows: In a mixed solution, antimony trichloride (SbCl3) undergoes a highly efficient hydrolysis-oxidation coupling reaction under high temperature and in an atmosphere of water vapor and hydrogen chloride provided by waste acid, directly generating the target product, antimony oxide (antimony white), and releasing hydrogen chloride gas. 2SbCl3 + 3H2O → Sb2O3 + 6HCl↑ (Main reaction) Waste acid here serves not only as a medium, but also contains H+. +and Cl - Furthermore, it participates in regulating the reaction equilibrium, inhibiting the stable existence of the intermediate product antimony oxychloride (SbOCl) and promoting its further decomposition: 3SbOCl → Sb2O3 + SbCl3. The atomized roasting method ensures that the above reaction proceeds rapidly and completely in a very short time, avoiding the problem of increased by-products caused by local overheating or incomplete reaction. The subsequent gradient cooling dust collection and segmented absorption processes are purification and separation schemes tailored for this specific reaction flue gas component (gas-solid mixture, containing corrosive gases), ensuring the purity of the final product and the stable operation of the entire system.

[0011] The main chemical reactions that occur during this process are as follows: 2SbCl3 + 3H2O = Sb2O3 + 6HCl (g) SbCl3 + H2O = SbClO + 2HCl (g) 3SbClO = Sb₂O₃ + SbCl 3 。

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention proposes for the first time a novel approach that involves mixing high- and low-boiling-point substances with waste acid from cleaning followed by unified atomization and roasting treatment. This concept breaks away from the long-standing divide-and-conquer mindset in the field, transforming the treatment of the two types of waste from a simple environmental burden issue into an opportunity for the synergistic extraction of resources.

[0013] 2. This method elevates the recovery of antimony from a low-value intermediate product (antimony oxychloride) to a high-value final product (high-purity antimony white, Sb₂O₃ ≥ 99.5%) that can be directly sold. Simultaneously, it achieves for the first time the transformation of chlorine from a pollutant to a product (industrial hydrochloric acid). Examples show that the antimony recovery rate remains stable above 97%, and the chlorine recovery rate reaches over 85%, maximizing resource utilization.

[0014] 3. This process, through internal material circulation and reaction design, completely eliminates the process that generates a large amount of acidic wastewater in traditional hydrolysis processes, achieving near-zero discharge of production wastewater and solving the core environmental problem that has plagued the industry.

[0015] 4. Two independent waste-producing processing lines are innovatively integrated and optimized into a continuous clean production line that produces two valuable products. The process flow is more compact, the utilization of materials and energy is more rational, and the operating cost is more advantageous.

[0016] 5. This invention turns waste into treasure, solves environmental problems while creating direct economic benefits, reduces the overall cost of high-purity antimony production, enhances industrial competitiveness, and conforms to the development direction of green circular economy. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the method described in this invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. Example 1

[0019] The high- and low-boiling-point substances produced during the production of high-purity antimony are mainly composed of antimony trichloride, and the waste acid is mainly composed of hydrochloric acid at a concentration of about 20-25%. The composition of the high- and low-boiling-point substances is shown in the table below: High and low boiling points materials Sb (%) As (%) Cl（%） High and low boiling points 40.15 0.12 42.32 High- and low-boiling-point substances were mixed with waste acid at a volume ratio of 1:0.3. After mixing for 1 hour, the mixed solution was sprayed into a roasting tower using compressed air for roasting. During roasting, the temperature of the roasting tower was controlled at 650℃, the negative pressure at -70Pa, the inlet temperature of the settling chamber at 350℃, and the outlet temperature at 150℃. The inlet temperature of the bag filter was controlled at 140℃, and the outlet temperature at 110℃. After roasting, antimony white was removed from the settling chamber and the bag filter. The flue gas from the outlet of the bag filter entered a two-stage water spray tower for absorption. The exhaust gas after absorption was then absorbed by an alkaline spray tower and discharged in compliance with standards. During the roasting, antimony white collection, and two-stage water spraying processes, samples of antimony white and by-product hydrochloric acid were taken for testing. The test results are as follows: Antimony white ingredients name <![CDATA[Sb2O3(%)]]> As (%) Cl（%） antimony white 99.52 0.0025 0.09 Byproduct hydrochloric acid components name HCl (%) Sb (g / L) As (mg / L) Byproduct hydrochloric acid 18.96 0.21 6.7 Example 2

[0020] The high- and low-boiling-point substances produced during the production of high-purity antimony are mainly composed of antimony trichloride, and the waste acid is mainly composed of hydrochloric acid at a concentration of about 20-25%. The composition of the high- and low-boiling-point substances is shown in the table below: High and low boiling points materials Sb (%) As (%) Cl（%） High and low boiling points 42.15 0.09 45.66 High- and low-boiling-point substances were mixed with waste acid at a volume ratio of 1:0.5. After mixing for 1 hour, the mixed solution was sprayed into a roasting tower using compressed air for roasting. During roasting, the temperature of the roasting tower was controlled at 600℃, the negative pressure at -50Pa, the inlet temperature of the settling chamber at 330℃, and the outlet temperature at 150℃. The inlet temperature of the bag filter was controlled at 135℃, and the outlet temperature at 120℃. After roasting, antimony white was removed from the settling chamber and the bag filter. The flue gas from the outlet of the bag filter entered a two-stage water spray tower for absorption. The exhaust gas after absorption was then absorbed by an alkaline spray tower and discharged in compliance with standards. During the roasting, antimony white collection, and two-stage water spraying processes, samples of antimony white and by-product hydrochloric acid were taken for testing. The test results are as follows: Antimony white ingredients name <![CDATA[Sb2O3(%)]]> As (%) Cl（%） antimony white 99.61 0.0015 0.11 Byproduct hydrochloric acid components name HCl (%) Sb (g / L) As (mg / L) Byproduct hydrochloric acid 21.37 0.19 4.86 The above embodiments demonstrate that the method of the present invention can stably and efficiently process high and low boiling points and waste acid in the production of high-purity antimony, obtain high-quality antimony white and industrial hydrochloric acid, has a high resource recovery rate, is environmentally friendly, and has good prospects for industrial application.

[0021] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for the comprehensive recovery and utilization of high- and low-boiling-point substances and waste acid in the production process of high-purity antimony, characterized in that, Includes the following steps: (1) Mixing: The high and low boiling point substances containing antimony trichloride produced during the production of high-purity antimony are mixed with the hydrochloric acid waste acid produced during equipment cleaning. The mixing volume ratio of the high and low boiling point substances to the waste acid is 1:0.3 to 1:1, and the mixing time is 0.5 to 1 hour. (2) Atomization roasting: The mixed solution obtained in step (1) is atomized and sprayed into the roasting tower and roasted at a temperature of 500℃~700℃ to convert the antimony in the high and low boiling products into antimony oxide and release hydrogen chloride gas at the same time. (3) Collecting antimony white: The flue gas containing antimony oxide dust generated in step (2) is subjected to sedimentation separation and bag filter dust removal in sequence to collect the antimony white product; (4) Absorption for acid production and tail gas treatment: The tail gas containing hydrogen chloride gas after dust removal in step (3) is passed into at least one water spray absorption tower for absorption to obtain hydrochloric acid as a by-product; the tail gas after water absorption is then treated by alkaline absorption before being discharged.

2. The method for comprehensive recovery and utilization of high and low boiling points and waste acid in the high-purity antimony production process according to claim 1, characterized in that: In step (2), the roasting is carried out under a slight negative pressure condition, and the pressure inside the roasting tower is -50 Pa to -100 Pa.

3. The method for comprehensive recovery and utilization of high and low boiling points and waste acid in the high-purity antimony production process according to claim 1 or 2, characterized in that: In step (2), the atomization is achieved by dispersing the mixed solution into fine droplets by compressed air; the inlet pressure of the mixed solution is 0.1 to 0.3 MPa, and the pressure of the compressed air is 0.3 to 0.6 MPa.

4. The method for comprehensive recovery and utilization of high and low boiling points and waste acid in the high-purity antimony production process according to claim 1 or 2, characterized in that: In step (2), the heat source of the roasting tower is selected from electric heating, gas heating or water gas heating.

5. The method for comprehensive recovery and utilization of high and low boiling points and waste acid in the high-purity antimony production process according to claim 1 or 2, characterized in that: In step (3), the settling separation is carried out in the settling chamber, and the inlet temperature of the flue gas is controlled at 300℃~350℃ and the outlet temperature is controlled at 120℃~150℃.

6. The method for comprehensive recovery and utilization of high and low boiling points and waste acid in the high-purity antimony production process according to claim 1 or 2, characterized in that: In step (3), the bag dust removal is carried out in a bag dust collector, and the inlet temperature of the flue gas is controlled to be 120℃~150℃ and the outlet temperature is 100℃~120℃.

7. The method for comprehensive recovery and utilization of high and low boiling points and waste acid in the high-purity antimony production process according to claim 5, characterized in that: The settling chamber is made of stainless steel that is resistant to chloride corrosion.

8. The method for comprehensive recovery and utilization of high and low boiling points and waste acid in the high-purity antimony production process according to claim 1 or 2, characterized in that: In step (4), a two-stage water spray absorption tower is used for absorption, and the concentration of the by-product hydrochloric acid is 18% to 22%.

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