Arsenic-containing gold concentrate pre-dearsenization and arsenic recovery system and process based on steel belt furnace

Abstract

This invention discloses a pre-arsenic removal and arsenic recovery system and process for arsenic-containing gold concentrate based on a steel belt furnace, belonging to the field of arsenic-containing mineral resource processing technology. The system includes a raw material processing unit, an arsenic removal unit, a flue gas treatment unit, and a product collection unit, with its core equipment being a sealed, slightly negative-pressure steel belt furnace. The process involves evenly spreading the arsenic-containing gold concentrate onto the conveyor belt of the steel belt furnace using a feeding device, completing the pre-arsenic removal reaction at a temperature of 580-650℃ under slightly negative pressure conditions, and obtaining low-arsenic gold concentrate after cooling. The generated arsenic-containing flue gas is treated through secondary combustion of natural gas, pipeline crystallization, and baghouse dust collection to recover arsenic trioxide. The tail gas is treated by an absorption tower before being discharged in compliance with standards. This invention can remove arsenic from gold concentrate with an arsenic content of 10-15% to below 0.5%, with a unit processing cost of only 700 yuan / ton. It effectively solves the technical problems of difficult removal of sulfur arsine and easy pipeline blockage in existing technologies, combining high efficiency, environmental friendliness, and economy.

Description

Technical Field

[0001] This invention relates to the field of arsenic-containing mineral resource processing technology, specifically to a pre-arsenic removal and arsenic recovery system and process for arsenic-containing gold concentrate based on a steel strip furnace. Background Technology

[0002] Gold, as an important precious metal, plays an irreplaceable role in industrial production and financial reserves. With the increasing depletion of readily processable gold mine resources globally, the development and utilization of high-arsenic gold concentrate has become a crucial way to alleviate gold resource shortages. my country's gold concentrate reserves are limited, while foreign countries possess abundant high-arsenic gold concentrate resources, but these contain arsenic content as high as 10-15%. Directly using traditional processing methods would lead to high reagent consumption and low gold recovery rates during subsequent gold extraction, and arsenic leakage would cause severe environmental pollution, while also generating large amounts of pollutants, further exacerbating environmental pressures.

[0003] Existing arsenic removal technologies for arsenic-containing gold concentrates face numerous unresolved issues, with environmental shortcomings being particularly prominent: traditional roasting pretreatment equipment is prone to arsenic flue gas leakage, and processes such as wet leaching are susceptible to secondary pollution; processes like roasting pretreatment, microbial oxidation, and high-pressure oxygen leaching also generate large amounts of water-containing wastewater and hazardous solid waste, which are difficult and costly to treat, and easily cause soil and water pollution. Furthermore, roasting arsenic removal methods suffer from poor process stability and difficulty in completely removing arsine from arsenic-containing flue gas, not only causing secondary pollution but also affecting the quality of arsenic trioxide products. Simultaneously, existing technologies generally suffer from limited processing scale, poor adaptability, complex processes, and high costs, resulting in poor economic viability and failing to meet the practical need to alleviate the domestic gold concentrate shortage by utilizing high-arsenic gold concentrates from abroad.

[0004] In view of the shortcomings of the existing technologies, there is an urgent need to develop a system and process that can achieve efficient pre-arsenic removal from high-arsenic gold concentrate, high arsenic resource recovery and utilization rate, environmental friendliness and large-scale application. This has become a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and to provide a system and process for pre-arsenic removal and arsenic recovery of arsenic-containing gold concentrate based on a steel strip furnace.

[0006] The specific solution of the present invention is: a pre-arsenic removal and arsenic recovery system for arsenic-containing gold concentrate based on a steel strip furnace, comprising a raw material processing unit, an arsenic removal unit, a flue gas treatment unit and a product collection unit;

[0007] The raw material processing unit includes a material distribution device, preferably a roller-type material distributor, which is used to evenly distribute the arsenic-containing gold concentrate to the arsenic removal unit to ensure that the arsenic removal reaction is uniform and sufficient, and to avoid local overheating or incomplete arsenic removal. The material thickness can be flexibly adjusted according to actual processing needs.

[0008] The arsenic removal unit is a sealed steel strip furnace, which is the core equipment of the entire system. The steel strip furnace is equipped with an arsenic removal zone, which is equipped with a heating mechanism (preferably an electric heating mechanism) to precisely control the arsenic removal temperature. The steel strip furnace is maintained under a slight negative pressure (approximately -10 kPa), which is precisely maintained by a negative pressure control system to effectively prevent arsenic flue gas leakage and ensure smooth discharge of arsenic flue gas, avoiding the entry of outside air that could cause an imbalance in the oxidation atmosphere inside the furnace. The discharge end of the steel strip furnace is sealed and connected to a cooling mechanism (preferably an air-cooled mechanism) to achieve rapid cooling of the arsenic-removed gold concentrate to room temperature and prevent secondary oxidation.

[0009] The flue gas treatment unit is sequentially and sealed along the flow direction of the arsenic-containing flue gas, consisting of a secondary combustion device, a pipeline crystallization mechanism, a bag filter, and an absorption tower. The secondary combustion device is equipped with a natural gas supply component (preferably a natural gas spray gun) to completely decompose arsenic sulfur in the arsenic-containing flue gas through natural gas combustion, while avoiding pipeline blockage and improving the subsequent arsenic trioxide recovery quality. The pipeline crystallization mechanism (preferably a stainless steel crystallization pipeline with an external cooling water jacket) is used to condense and crystallize arsenic trioxide in the flue gas. The bag filter (preferably a pulse-jet bag filter with PTFE filter bags) achieves efficient collection of arsenic trioxide. The absorption tower (preferably a spray absorption tower filled with sodium hydroxide absorbent) provides deep treatment of the exhaust gas to ensure compliance with emission standards.

[0010] The product collection unit includes an arsenic-free gold concentrate collection bin and an arsenic trioxide collection bin, which are respectively connected to the discharge end of the cooling mechanism and the discharge end of the bag dust collector via a sealed screw conveyor, so as to realize the classified collection and sealed storage of the two products and avoid secondary pollution.

[0011] Furthermore, the heating temperature control range of the arsenic removal zone is 580-650℃. This temperature range ensures that arsenic is fully volatilized and removed, while avoiding excessive loss of effective components in the gold concentrate. The temperature can be finely adjusted in a timely manner according to the arsenic content of the raw material. The internal micro-negative pressure value of the steel strip furnace is about -10kPa, which is precisely maintained by the negative pressure control system. This ensures that the arsenic flue gas can be discharged smoothly, prevents the entry of outside air that could cause an imbalance in the oxidation atmosphere inside the furnace, and eliminates environmental pollution caused by arsenic flue gas leakage.

[0012] Furthermore, the secondary combustion device is connected to the flue gas outlet of the steel strip furnace by a flange seal, and the pipeline crystallization mechanism is connected to the bag dust collector by a sealed pipeline. The fully sealed design further enhances the environmental friendliness of the system and completely eliminates arsenic flue gas leakage.

[0013] This invention also discloses a process for pre-arsenic removal and arsenic recovery of arsenic-containing gold concentrate based on the above system, comprising the following steps:

[0014] S1: Raw material pretreatment, arsenic-containing gold concentrate with arsenic content of 10-15% and sulfur content of 30% is evenly spread on the conveyor belt of the steel belt furnace through a material spreading device. The material spreading thickness is adapted and adjusted according to the steel belt conveying speed and arsenic removal efficiency (preferably 80mm).

[0015] S2: Pre-arsenic removal treatment. The heating mechanism of the steel belt furnace is started, and the temperature of the arsenic removal zone is adjusted to 580-650℃. A slight negative pressure of about -10kPa is maintained in the furnace through the negative pressure control system. The arsenic-containing gold concentrate is conveyed to the arsenic removal zone at a uniform speed with the steel belt. Under this temperature and pressure conditions, the arsenic removal reaction takes place. The arsenic element is converted into arsenic-containing flue gas and volatilized and separated. The gold concentrate remains on the steel belt and continues to be conveyed, resulting in preliminarily arsenic-removed gold concentrate and arsenic-containing flue gas. The steel belt conveying speed can be flexibly adjusted according to the processing volume (preferably 0.8m / min), and the arsenic removal reaction time can be adjusted accordingly (preferably 30min).

[0016] S3: Cooling of the dearsenic-removed product. The preliminary dearsenic-removed gold concentrate obtained in step S2 is conveyed to the cooling mechanism by a steel belt. After being cooled to room temperature, it is sent to the dearsenic-removed gold concentrate collection bin by a sealed screw conveyor. The cooled dearsenic-removed gold concentrate has an arsenic content of less than 0.5% and a sulfur content of 27%.

[0017] S4: Flue gas treatment and arsenic recovery. The arsenic-containing flue gas obtained in step S2 is introduced into a secondary combustion device through a sealed pipeline. Natural gas is introduced into the secondary combustion device and ignited. The arsenic sulfur in the flue gas is completely decomposed through secondary combustion. The flue gas after combustion enters the pipeline crystallization mechanism. Under the cooling effect of the cooling water jacket (preferably the cooling water temperature is controlled at 25°C), the arsenic trioxide in the flue gas condenses and crystallizes to form solid particles. The flue gas carrying the arsenic trioxide particles enters the bag filter dust collector. The arsenic trioxide is intercepted and collected by the filter bags (preferably the filtration velocity is 0.8 m / min). The collected arsenic trioxide is sent to the arsenic trioxide collection bin by a sealed screw conveyor. The tail gas discharged from the bag filter dust collector is introduced into the absorption tower. After being absorbed and treated by the absorbent (preferably the pH value of the absorbent is maintained at 8-9), it meets the emission standards. The arsenic content in the tail gas is less than 0.5 mg / m³, which meets the requirements of the "Emission Standard of Air Pollutants for Industrial Furnaces and Kilns" (GB 9078-1996).

[0018] S5: System operation and maintenance, regularly inspect and clean equipment such as steel strip furnace and bag dust collector to ensure stable system operation; specifically: inspect the steel strip in the steel strip furnace every 8 hours of operation, and clean the filter bags of the bag dust collector every 24 hours; adjust parameters such as arsenic removal temperature and steel strip speed in a timely manner according to changes in raw material composition to ensure stable treatment effect.

[0019] Furthermore, the unit cost of processing arsenic-containing gold concentrate in the steel strip furnace is 700 yuan / ton, which significantly reduces the processing cost compared to traditional processes and improves the economic efficiency of the process; among which, the energy consumption cost is 350 yuan / ton, the natural gas cost is 100 yuan / ton, the equipment operation and maintenance cost is 100 yuan / ton, and the labor and other costs are 150 yuan / ton.

[0020] The present invention has the following beneficial effects:

[0021] 1. High arsenic removal efficiency and superior product quality: By precisely controlling the arsenic removal temperature of 580-650℃ and the micro-negative pressure (-10kPa) inside the furnace, the arsenic content of arsenic-containing gold concentrate can be reduced from 10-15% to below 0.5%, with significant arsenic removal effect, meeting the requirements of subsequent gold extraction processes; at the same time, the setting of the secondary combustion device completely decomposes sulfur arsine, solving the problem of easy pipe blockage in existing technologies, improving the purity of arsenic trioxide products (purity can reach over 99.5%), and achieving efficient recovery of arsenic resources.

[0022] 2. High environmental safety: The steel strip furnace adopts a sealed design and maintains a slightly negative pressure state. Combined with a fully sealed flue gas treatment pipeline and product conveying mechanism, it effectively prevents arsenic flue gas leakage. The arsenic-containing flue gas is discharged in compliance with standards after secondary combustion, crystallization recovery and absorption treatment. No large amount of water-containing wastewater and hazardous solid waste are generated throughout the process, realizing the recycling of arsenic resources and zero excessive emission of pollutants, meeting green environmental protection requirements and reducing environmental disposal pressure from the source.

[0023] 3. High adaptability and flexible processing scale: This system can realize continuous large-scale processing of arsenic-containing gold concentrate, with a processing capacity of up to 50 tons / day. It is especially suitable for the development and utilization of high-arsenic gold concentrate resources abroad, effectively alleviating the shortage of gold concentrate in China. At the same time, it can also be adapted to the processing of small-scale gold concentrate. The process has good adaptability to high-arsenic gold concentrate of different grades, and the processing effect can be ensured by fine-tuning the parameters.

[0024] 4. Good economic efficiency and strong practicality: The unit cost of processing arsenic-containing gold concentrate by steel strip furnace is only 700 yuan / ton, which is 41.7% lower than the traditional rotary kiln arsenic removal process (unit cost 1200 yuan / ton). At the same time, it realizes the recycling and value-added of arsenic resources. The recovered arsenic trioxide can be sold as a chemical raw material, which further improves the economic feasibility of the process and facilitates its industrial promotion and application. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process principle of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0028] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0029] Example 1

[0030] See details Figure 1 A pre-arsenic removal and arsenic recovery system for arsenic-containing gold concentrate based on a steel strip furnace includes a raw material processing unit, an arsenic removal unit, a flue gas treatment unit, and a product collection unit.

[0031] The raw material processing unit uses a roller-type material feeder to ensure uniform distribution of arsenic-containing gold concentrate, with the material thickness controlled at 80mm.

[0032] The arsenic removal unit is a sealed steel strip furnace with a steel strip width of 1m and a conveying speed of 0.8m / min. The steel strip furnace is equipped with an arsenic removal zone and an electric heating mechanism, which can achieve precise temperature control of 580-650℃. The steel strip furnace maintains a slightly negative pressure state inside through a vacuum pump, and the negative pressure value is stable at -10MPa. The discharge end of the steel strip furnace is connected to an air-cooling mechanism.

[0033] The flue gas treatment unit is sequentially connected to a secondary combustion furnace, a stainless steel crystallization pipe, a pulse-jet bag filter, and a spray absorption tower along the flow direction of the arsenic-containing flue gas. The secondary combustion furnace is equipped with a natural gas spray gun. The crystallization pipe is equipped with a cooling water jacket, and the cooling water temperature is controlled at 25℃. The filter bags of the bag filter are made of polytetrafluoroethylene, and the filtration velocity is 0.8m / min. The absorption tower is filled with sodium hydroxide absorbent, and the pH value of the absorbent is maintained at 8-9.

[0034] The product collection unit includes a 50m³ arsenic-free gold concentrate collection bin and a 10m³ arsenic trioxide collection bin, which are respectively connected to the discharge end of the air-cooling mechanism and the discharge end of the pulse-jet bag filter dust collector via sealed screw conveyors.

[0035] The process of pre-arsenic removal and arsenic recovery from arsenic-containing gold concentrate using the above system is as follows:

[0036] S1: Raw material pretreatment: Select high-arsenic gold concentrate from abroad with arsenic content of 15% and sulfur content of 30%, and spread it evenly on the conveyor belt of the steel belt furnace using a roller-type material distributor with a thickness of 80mm.

[0037] S2: Pre-arsenic removal treatment. Start the electric heating mechanism to adjust the temperature of the arsenic removal zone to 650℃. Start the vacuum pump to maintain a slight negative pressure of -10MPa in the furnace. Control the steel belt conveying speed to 0.8m / min. The arsenic-containing gold concentrate is conveyed to the arsenic removal zone with the steel belt for arsenic removal reaction. The reaction time is 30min.

[0038] S3: Cooling of the dearsenic-removed product. The dearsenic-removed gold concentrate is conveyed to the air-cooling mechanism by the steel belt. After being air-cooled to room temperature, it is sent to the dearsenic-removed gold concentrate collection bin by a sealed screw conveyor. After testing, the arsenic content of the cooled dearsenic-removed gold concentrate is less than 0.5%, and the sulfur content is about 27%.

[0039] S4: Flue gas treatment and arsenic recovery. The arsenic-containing flue gas generated from arsenic removal is introduced into the secondary combustion furnace through a sealed pipeline. The natural gas injection gun is started, natural gas is introduced and ignited, and the arsenic-containing flue gas is fully combusted in the secondary combustion furnace, decomposing the sulfur arsine. The flue gas after combustion enters the stainless steel crystallization pipeline. Under the cooling effect of the cooling water jacket, the arsenic trioxide in the flue gas condenses and crystallizes into solid particles. The flue gas carrying the arsenic trioxide particles enters the pulse-jet bag filter, where the arsenic trioxide is intercepted and collected by the polytetrafluoroethylene filter bags. The collected arsenic trioxide is sent to the arsenic trioxide collection bin by a screw conveyor. After testing, the purity of the arsenic trioxide is above 99.5%. The tail gas discharged from the bag filter is introduced into the spray absorption tower. After being absorbed and treated by sodium hydroxide absorbent, the arsenic content in the tail gas is less than 0.5 mg / m³, which meets the requirements of the "Emission Standard of Air Pollutants for Industrial Furnaces and Kilns" (GB9078-1996) and is discharged in compliance with the standard.

[0040] S5: System operation and maintenance. Check the steel strip in the steel strip furnace every 8 hours of operation and clean the filter bags of the bag dust collector every 24 hours to ensure stable system operation. Adjust the arsenic removal temperature in a timely manner according to the changes in the arsenic content of the raw materials. When the arsenic content of the raw materials is 15%, increase the arsenic removal temperature to 650℃ to ensure that the arsenic content after arsenic removal is less than 0.5%.

[0041] In this embodiment, the unit cost of processing arsenic-containing gold concentrate in a steel strip furnace is 700 yuan / ton, including energy consumption cost of 350 yuan / ton, natural gas cost of 100 yuan / ton, equipment operation and maintenance cost of 100 yuan / ton, and labor and other costs of 150 yuan / ton. Compared with the traditional rotary kiln arsenic removal process (unit cost of 1200 yuan / ton), the cost is reduced by 41.7%.

[0042] This embodiment realizes large-scale continuous processing of high-arsenic gold concentrate, with a processing capacity of up to 50 tons / day. The processed arsenic-free gold concentrate can be directly fed into subsequent gold extraction processes, and the recovered arsenic trioxide can be sold as a chemical raw material, realizing comprehensive utilization of resources. At the same time, the entire process has no arsenic flue gas leakage, and the tail gas meets emission standards, resulting in significant environmental benefits.

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A pre-arsenic removal and arsenic recovery system for arsenic-containing gold concentrate based on a steel strip furnace, characterized in that, It includes a raw material processing unit, an arsenic removal unit, a flue gas treatment unit, and a product collection unit; The raw material processing unit includes a feeding device for uniformly feeding arsenic-containing gold concentrate to the arsenic removal unit to ensure that the arsenic removal reaction is uniform and sufficient. The arsenic removal unit is a sealed steel strip furnace. An arsenic removal zone is set inside the steel strip furnace. The arsenic removal zone is equipped with a heating mechanism. The inside of the steel strip furnace is maintained under a slight negative pressure. A cooling mechanism is sealed and connected to the discharge end of the steel strip furnace. The flue gas treatment unit is sequentially and sealed to a secondary combustion device, a pipeline crystallization mechanism, a bag filter and an absorption tower along the flow direction of the arsenic-containing flue gas. The secondary combustion device is equipped with a natural gas supply component for introducing natural gas into the secondary combustion device. The product collection unit includes an arsenic-free gold concentrate collection bin and an arsenic trioxide collection bin, which are respectively sealed and connected to the discharge end of the cooling mechanism and the discharge end of the bag dust collector, so as to realize the separate collection of the two products.

2. The pre-arsenic removal and arsenic recovery system for arsenic-containing gold concentrate based on a steel strip furnace according to claim 1, characterized in that, The heating temperature control range of the arsenic removal zone is 580-650℃; the internal micro-negative pressure value of the steel strip furnace is -10kPa, which is precisely maintained by the negative pressure control system.

3. The pre-arsenic removal and arsenic recovery system for arsenic-containing gold concentrate based on a steel strip furnace according to claim 1, characterized in that, The secondary combustion device is connected to the flue gas outlet of the steel strip furnace by a flange seal, and the pipeline crystallization mechanism is connected to the bag dust collector by a sealed pipeline. The entire process is sealed to prevent arsenic flue gas leakage.

4. A process for pre-arsenic removal and arsenic recovery of arsenic-containing gold concentrate based on a steel strip furnace according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Raw material pretreatment, the arsenic-containing gold concentrate is evenly spread on the conveyor belt of the steel belt furnace through the material spreading device, and the material spreading thickness is adjusted according to the conveyor speed of the steel belt and the arsenic removal efficiency. S2: Pre-arsenic removal treatment, control the temperature of the arsenic removal zone of the steel strip furnace to 580-650℃, maintain a slight negative pressure state of about -10kPa in the furnace, and the arsenic-containing gold concentrate is uniformly conveyed to the arsenic removal zone with the steel strip to complete the arsenic removal reaction, and obtain arsenic-removed gold concentrate and arsenic-containing flue gas. S3: Cooling of arsenic removal products. The arsenic removal gold concentrate obtained in step S2 is cooled to room temperature by a cooling mechanism and then sent to the arsenic removal gold concentrate collection bin. S4: Flue gas treatment and arsenic recovery. The arsenic-containing flue gas obtained in step S2 is fed into a secondary combustion device, and natural gas is introduced for secondary combustion to completely decompose sulfur arsenide. After combustion, the flue gas is condensed and crystallized by a pipeline crystallization mechanism, and then enters a bag filter to recover arsenic trioxide. The recovered arsenic trioxide is sent to an arsenic trioxide collection bin. The exhaust gas discharged from the bag filter is treated by an absorption tower and then discharged in compliance with standards.

5. The process according to claim 4, characterized in that, The arsenic-containing gold concentrate in step S1 has an arsenic content of 10-15% and a sulfur content of 30%; the arsenic-free gold concentrate obtained in step S3 has an arsenic content of less than 0.5% and a sulfur content of 27%.

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