Environment-friendly treatment facility and method for drying and reducing arsenic sulfide slag of smelting enterprise

Abstract

The invention provides an environment-friendly treatment facility and method for drying and reducing arsenic sulfide slag of a smelting enterprise, and relates to the technical field of solid waste treatment and environment-friendly treatment. The environment-friendly treatment facility and method for drying and reducing the arsenic sulfide slag of the smelting enterprise comprise the following steps that S1, arsenic sulfide generated by water treatment filter pressing is subjected to primary drying through a polytetrafluoroethylene anticorrosive coating heat exchanger in an indirect heat exchange mode, the drying temperature is controlled to range from 120 DEG C to 180 DEG C, and the drying time is controlled to range from 20 min to 60 min; and S2, the semi-dried material obtained in the step S1 is conveyed to a corrosion-resistant crusher through automatic equipment to be crushed, the crusher crushes the material till the granularity is 20-100 meshes, and free water and crystal water in the arsenic sulfide slag can be further dried conveniently. And the generated waste gas and particulate matters are effectively collected and treated, so that the risk that the generated foul gas such as hydrogen sulfide pollutes the environment is avoided, environmental protection is more and more paid attention in recent years, and the technology has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment and environmental protection management, and in particular to an environmental protection treatment facility and method for drying and reducing arsenic sulfide slag in a smelting enterprise. Background Art

[0002] Arsenic is usually enriched in waste acids and wastewaters from industrial processes such as metal smelting, arsenic compound preparation, and even deep processing of arsenic products. In order to efficiently remove arsenic from these waste acids and wastewaters, most companies use sulfide precipitation to treat them, which produces a large amount of arsenic sulfide slag. Arsenic sulfide slag is a hazardous waste with large production volumes and high disposal costs, which directly affects the economic benefits of smelting companies and increases the comprehensive disposal costs of hazardous waste management units. Therefore, how to efficiently dry and reduce the arsenic sulfide slag is particularly critical.

[0003] Currently, two main drying and weight reduction technologies have been identified. The first involves using high-temperature drum drying to dehydrate and dry arsenic sulfide slag. This technology involves heating wet arsenic sulfide slag in a drum dryer, where high-temperature hot air is brought into contact with the wet arsenic sulfide slag. This vaporizes and volatilizes the moisture in the wet arsenic sulfide slag, producing dry arsenic sulfide slag. This method requires a dedicated hot air furnace to generate the high-temperature hot air and a large drum dryer. The resulting high-temperature hot air, at 650°C to 800°C, can easily ignite the dried arsenic sulfide slag, posing a safety hazard and limiting its removal capacity. Furthermore, because arsenic sulfide slag is highly sticky and prone to agglomeration, the moisture trapped within the arsenic sulfide is difficult to evaporate, resulting in uneven drying and high residual moisture content. Furthermore, since the arsenic sulfide slag is sticky before drying, and agglomerates during drying, interrupting the drying process to break up the arsenic sulfide slag to allow for more moisture volatilization wastes energy.

[0004] Method 2 is to use microwaves as a heating method to dehydrate and dry arsenic sulfide slag. Although it saves investment to a certain extent compared to the use of high-temperature drum drying technology, it still requires additional microwave energy consumption, and does not solve the corrosion problems of high fluorine and high chlorine in arsenic sulfide slag to equipment, as well as the irritating and malodorous gas emissions generated by drying waste gas. Therefore, technicians in this field provide an environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in smelting enterprises to solve the problems raised in the above background technology. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the deficiencies in the prior art, the present invention provides an environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in smelting enterprises, which solves the problems of high residual water content, easy corrosion to equipment and waste gas emissions in the existing treatment methods.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: an environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in a smelting enterprise, comprising the following steps:

[0009] S1. The arsenic sulfide produced by water treatment and filtration is dried using a polytetrafluoroethylene (PTFE) anti-corrosion coated heat exchanger via indirect heat exchange. The drying temperature is controlled between 120°C and 180°C, and the drying time is controlled between 20 and 60 minutes. The drying heat source is waste heat from the smelting furnace, thus avoiding equipment corrosion and the need for additional energy.

[0010] S2. The semi-dried material obtained in step S1 is sent to a corrosion-resistant crusher by automated equipment for crushing. The crusher is coated with a metal corrosion-resistant coating or a polytetrafluoroethylene coating. The crusher reduces the particle size of the material to 20 to 100 mesh, which facilitates further drying of the free water and crystal water in the arsenic sulfide slag.

[0011] S3. The crushed material obtained in step S2 is dried for a second time at a temperature of 300 to 450°C. The second drying temperature should be maintained for 20 to 60 minutes.

[0012] S4. During the above-mentioned drying and crushing process, arsenic sulfide slag will produce a certain amount of water vapor, hydrogen sulfide, hydrogen fluoride, hydrogen chloride, sulfuric acid vapor and a small amount of particulate matter. The waste gas and particulate matter generated can be introduced into the secondary alkaline washing spray tower through a negative pressure draft device for neutralization and washing treatment to ensure that the waste gas meets the emission standards.

[0013] Preferably, in step S1, an infrared moisture meter is installed at the drying outlet to dynamically adjust the drying time to ensure that the moisture content of the material is reduced to 15% to 20%.

[0014] Preferably, in the step S2, nitrogen with a content of ≤5% is introduced into the crushing chamber, and a temperature sensor is installed for explosion prevention.

[0015] Preferably, the second drying in step S3 is first preheated at 250° C. for 10 minutes to prevent the thermal decomposition of arsenic sulfide to produce highly toxic arsenic trioxide vapor.

[0016] (3) Beneficial effects

[0017] The present invention provides an environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in smelting enterprises. It has the following beneficial effects:

[0018] 1. Compared with the method of high-temperature flue gas heating or microwave heating, the present invention avoids direct contact of arsenic sulfide slag with flue gas and other substances, avoids a significant increase in gas volume during the drying process, and avoids increasing the scale and cost of tail gas treatment facilities. Compared with traditional steam or microwave heating methods, it can directly rely on the waste heat generated by the smelting furnace of non-ferrous metal enterprises, without the need for additional natural gas combustion, electricity consumption, etc., thus saving energy and not generating a large amount of condensed water.

[0019] 2. In the present invention, the material can be subjected to a combination of primary drying, material crushing and secondary drying, so that the water molecular structure in the form of free water and bound water in the arsenic sulfide slag is destroyed, the volatilization rate of water is accelerated, the dehydration rate is improved, the drying time is shortened, and the production efficiency is improved. During the drying process, the material expands due to heat, which destroys the original pore structure in the material, reducing the problem of moisture absorption after drying.

[0020] 3. In the present invention, the waste gas and particulate matter generated are effectively collected and treated, avoiding the risk of malodorous gases such as hydrogen sulfide polluting the environment. Environmental protection has received increasing attention in recent years, and this technology has broad application prospects.

[0021] 4. In the present invention, microwave heating technology has the advantages of low equipment investment, significant reduction of hazardous waste, and good economy. It is particularly suitable for use in large and medium-sized non-ferrous metal smelting enterprises. Compared with traditional methods, it has the advantages of simple process, high processing efficiency, energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the overall system process of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1:

[0025] like Figure 1 As shown, the embodiment of the present invention provides an environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in a smelting enterprise, including the following steps:

[0026] S1. The arsenic sulfide produced by water treatment and filtration is dried using a polytetrafluoroethylene (PTFE) anti-corrosion coated heat exchanger via indirect heat exchange. The drying temperature is controlled between 120°C and 180°C, and the drying time is controlled between 20 and 60 minutes. The drying heat source is waste heat from the smelting furnace, thus avoiding equipment corrosion and the need for additional energy.

[0027] S2. The semi-dried material obtained in step S1 is sent to a corrosion-resistant crusher by automated equipment for crushing. The crusher is coated with a metal corrosion-resistant coating or a polytetrafluoroethylene coating. The crusher reduces the particle size of the material to 20 to 100 mesh, which facilitates further drying of the free water and crystal water in the arsenic sulfide slag.

[0028] S3. The crushed material obtained in step S2 is dried for a second time at a temperature of 300 to 450°C. The second drying temperature should be maintained for 20 to 60 minutes.

[0029] S4. During the above-mentioned drying and crushing process, arsenic sulfide slag will produce a certain amount of water vapor, hydrogen sulfide, hydrogen fluoride, hydrogen chloride, sulfuric acid vapor and a small amount of particulate matter. The waste gas and particulate matter generated can be introduced into the secondary alkaline washing spray tower through a negative pressure draft device for neutralization and washing treatment to ensure that the waste gas meets the emission standards.

[0030] In step S1, an infrared moisture meter is installed at the drying outlet to dynamically adjust the drying time to ensure that the moisture content of the material is reduced to 15% to 20%.

[0031] In step S2, nitrogen with a content of ≤5% is introduced into the crushing chamber, and a temperature sensor is installed for explosion prevention.

[0032] The second drying in step S3 is first preheated at 250° C. for 10 minutes to prevent the thermal decomposition of arsenic sulfide to produce highly toxic arsenic trioxide vapor.

[0033] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in a smelting enterprise, characterized by: The following steps are involved: S1. The arsenic sulfide produced by water treatment and filtration is dried using a polytetrafluoroethylene (PTFE) anti-corrosion coated heat exchanger via indirect heat exchange. The drying temperature is controlled between 120°C and 180°C, and the drying time is controlled between 20 and 60 minutes. The drying heat source is waste heat from the smelting furnace, thus avoiding equipment corrosion and the need for additional energy. S2. The semi-dried material obtained in step S1 is sent to a corrosion-resistant crusher by automated equipment for crushing. The crusher is coated with a metal corrosion-resistant coating or a polytetrafluoroethylene coating. The crusher reduces the particle size of the material to 20 to 100 mesh, which facilitates further drying of the free water and crystal water in the arsenic sulfide slag. S3. The crushed material obtained in step S2 is dried for a second time at a temperature of 300 to 450°C. The second drying temperature should be maintained for 20 to 60 minutes. S4. During the above-mentioned drying and crushing process, arsenic sulfide slag will produce a certain amount of water vapor, hydrogen sulfide, hydrogen fluoride, hydrogen chloride, sulfuric acid vapor and a small amount of particulate matter. The waste gas and particulate matter generated can be introduced into the secondary alkaline washing spray tower through a negative pressure draft device for neutralization and washing treatment to ensure that the waste gas meets the emission standards.

2. The environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in a smelting enterprise according to claim 1, characterized in that: In step S1, an infrared moisture meter is installed at the drying outlet to dynamically adjust the drying time to ensure that the moisture content of the material is reduced to 15% to 20%.

3. The environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in a smelting enterprise according to claim 1, characterized in that: In the step S2, nitrogen with a content of ≤5% is introduced into the crushing chamber, and a temperature sensor is installed for explosion prevention.

4. The environmentally friendly treatment facility and method for drying and reducing arsenic sulfide slag in a smelting enterprise according to claim 1, characterized in that: The second drying in step S3 is first preheated at 250° C. for 10 minutes to prevent the thermal decomposition of arsenic sulfide to produce highly toxic arsenic trioxide vapor.

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