Method for harmless treatment of waste white phosphorus and recovery of copper

Abstract

The invention discloses a method for harmless treatment of waste white phosphorus and recovery of copper, and belongs to the technical field of harmless treatment of hazardous waste, white phosphorus is dissolved in carbon disulfide, the carbon disulfide is slowly and dropwise added into a copper sulfate aqueous solution at the speed of 0.1-0.3 kg / min and reacts with the copper sulfate aqueous solution to generate copper and cuprous phosphide, and the cuprous phosphide is recycled. According to the method, the white phosphorus is dissolved in the carbon disulfide, the specific surface area of the white phosphorus is increased, the white phosphorus can be in full contact with the copper sulfate solution at the normal temperature to react to generate copper and cuprous phosphide, and the cuprous phosphide can be recycled after the reaction is finished. The method is simple, easy to operate and capable of saving chemicals, copper in copper sulfate is recycled while waste white phosphorus is subjected to innocent treatment, resources are reasonably utilized, cost is saved, safety and high efficiency are achieved, and good economic benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of harmless treatment of hazardous wastes, and specifically is a method for harmlessly treating waste white phosphorus and recovering copper. Background Art

[0002] White phosphorus, also known as yellow phosphorus, has the molecular formula P4. It is soft, brittle when cold, and a light yellow or white translucent solid. It darkens in light and is highly toxic. Inhaling 0.1 g of it can cause poisoning and death, and skin contact can also cause severe burns. Since white phosphorus is easy to spontaneously combust in the air and is toxic, it is usually stored in water to isolate it from the air and prevent it from spontaneously combusting and oxidizing when in contact with oxygen. In industry, white phosphorus is an important raw material for preparing phosphorus compounds such as high-purity phosphoric acid and organic phosphates. When exposed to air, white phosphorus produces blue-green phosphorescence and white smoke in the dark. It ignites at about 30°C in humid air, and the ignition point is slightly higher in dry air, about 40°C. However, the heat generated by friction or slow oxidation may cause the local temperature to reach 40°C and burn. Therefore, it cannot be guaranteed that white phosphorus will never spontaneously combust below 40°C. White phosphorus can spontaneously combust when in contact with air and cause combustion and explosion. The autoignition point in humid air is lower than the autoignition point in dry air. It is also prone to explosion when mixed with oxidants such as chlorates. Its fragments and debris can easily catch fire after contacting dry skin, causing severe skin burns. White phosphorus burns violently in oxygen, producing bright flames and thick white smoke, generating phosphorus pentoxide. Phosphorus pentoxide is a first-level inorganic acid corrosive product with strong irritation and corrosion. Its vapor and dust can irritate the human eye, oral mucosa and respiratory system, causing breathing difficulties. In severe cases, it can even cause toxic pneumonia and pulmonary edema. Skin exposed to phosphorus pentoxide will experience symptoms such as pain, itching, and redness. In severe cases, it may cause skin ulcers and necrosis. Summary of the invention

[0003] The purpose of the invention is to solve the potential safety hazards that may exist when waste white phosphorus is exposed to the air or accidentally mixed with an oxidant, and to provide a method for harmlessly treating waste white phosphorus and recovering copper. The waste white phosphorus can be slowly reacted with copper sulfate at normal temperature and pressure to generate elemental copper, cuprous phosphide, phosphoric acid and sulfuric acid, and copper can be recovered while the waste white phosphorus is safely treated. The problems of extremely easy spontaneous combustion, violent reaction, and release of a large amount of highly corrosive phosphorus pentoxide gas of white phosphorus are solved, resources are reasonably utilized, costs are saved, and the method is safe and efficient. Valuable metals can be recovered while the waste is treated, and good economic benefits are achieved.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for harmlessly treating waste white phosphorus and recovering copper, comprising the following steps: (1) dissolving copper sulfate pentahydrate in water to prepare a copper sulfate solution with a mass concentration of 21%; (2) dissolving 1 part by mass of waste white phosphorus in 2 to 4 parts by mass of carbon disulfide to prepare a white phosphorus-carbon disulfide mixed solution; (3) slowly adding the white phosphorus-carbon disulfide mixed solution prepared in step (2) to the copper sulfate solution prepared in step (1), wherein the mass ratio of white phosphorus to copper sulfate solution is 1:100, and stirring until the reaction is complete to obtain a reaction solution; (4) adding a 5% potassium borohydride solution to the reaction solution of step (3) and stirring, wherein the amount of the potassium borohydride solution added is 20 to 30 times the mass of the white phosphorus; (5) After the reaction is completed, the mixture is allowed to stand and filtered, and the filtrate is sent to a sewage treatment station for treatment. The filter residue is dried and roasted to recover the copper element.

[0005] As a further description of the above technical solution, the addition rate of the white phosphorus-carbon disulfide mixture in step (3) is 0.1 to 0.3 kg / min.

[0006] As a further description of the above technical solution, in step (3), the carbon disulfide gas generated during the reaction is collected and treated.

[0007] As a further description of the above technical solution, in step (4), the addition rate of potassium borohydride solution is 0.1 to 0.3 kg / min.

[0008] As a further description of the above technical solution, the drying in step (5) is performed at a temperature of 260-300° C. for 2 h.

[0009] As a further description of the above technical solution, the calcination in step (5) is carried out in a muffle furnace at 1100-1200° C. for 30 min.

[0010] The principle of the present invention is that: under normal temperature conditions (in a cold solution), white phosphorus (P4) reacts with a copper sulfate (CuSO4) aqueous solution to generate copper (Cu), phosphoric acid (H3PO4) and sulfuric acid (H2SO4); as the reaction proceeds, the reaction solution gradually heats up (exothermic reaction), and at this time, the remaining white phosphorus reacts with the copper sulfate aqueous solution to generate cuprous phosphide (Cu3P) precipitation, phosphoric acid (H3PO4) and sulfuric acid (H2SO4), so that the white phosphorus can be converted into copper phosphide and phosphoric acid, thereby achieving harmless treatment of the white phosphorus. However, copper generated in the initial stage of the reaction of block-shaped (non-molten state) white phosphorus with the copper sulfate solution will completely wrap the white phosphorus, so that the reaction of the wrapped white phosphorus with the copper sulfate is terminated, resulting in incomplete reaction of the white phosphorus. Because white phosphorus is very soluble in carbon disulfide, 1g of white phosphorus can be dissolved in 0.8ml of carbon disulfide. The specific surface area of ​​the dissolved white phosphorus increases, and it can fully contact with copper sulfate solution at room temperature to react to produce copper (Cu), cuprous phosphide (Cu3P), phosphoric acid (H3PO4) and sulfuric acid (H2SO4). The added potassium borohydride (KBH4) solution can reduce cuprous phosphide (Cu3P) to copper (Cu) element, thereby realizing copper recovery. At the same time, at room temperature, the white phosphorus in the copper sulfate solution will not spontaneously combust, ultimately meeting the requirements for safe treatment.

[0011] Compared with the prior art, the present invention has the following beneficial effects: (1) Ability to safely and harmlessly treat white phosphorus; (2) The problem that the copper generated during the reaction of block white phosphorus with copper sulfate solution was wrapped around the white phosphorus, resulting in the termination of the reaction and the problem of spontaneous combustion at 40°C was solved; (3) Reasonable use of resources, recycling valuable metal copper during waste treatment, saving resources and costs; (4) The operation is simple, easy to implement, the process is safe and stable, and it has good economic benefits. DETAILED DESCRIPTION

[0012] The following is a clear and complete description of the technical solution in the implementation of the invention. Obviously, the described embodiment is only one of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0013] A method for harmlessly treating waste white phosphorus and recovering copper comprises the following steps: (1) At room temperature and pressure, weigh 21 g of copper sulfate pentahydrate (analytical grade, content greater than 99.0%) in a glass reactor, add water to 100 g, and stir until the copper sulfate pentahydrate is completely dissolved to obtain a copper sulfate solution with a mass concentration of 21%; (2) Weigh 3 g of carbon disulfide solution and add 1 g of white phosphorus, stirring thoroughly until the white phosphorus is completely dissolved to obtain a white phosphorus-carbon disulfide mixed solution; (3) under stirring, the white phosphorus-carbon disulfide mixed solution is slowly added dropwise to the copper sulfate solution at a dropping speed of 0.3 kg / min, and after the addition is completed, stirring is continued for 3 hours until the reaction is complete to obtain a reaction solution, wherein the white phosphorus reacts with the copper sulfate aqueous solution to generate elemental copper, cuprous phosphide, phosphoric acid and sulfuric acid, and as the reaction temperature increases, the carbon disulfide in the reaction system will escape and volatilize, and in order to protect the environment, the escaped carbon disulfide volatile gas needs to be collected and treated; (4) 20 g of 5% potassium borohydride solution was added dropwise to the reaction solution at a dropping rate of 0.3 kg / min, and the reaction was continued with stirring for 1 h. Cuprous phosphide was reduced to elemental copper by the reducing agent potassium borohydride. After the reaction was completed, the solution was allowed to stand for 2 h to allow the elemental copper to precipitate. After standing, the solution was filtered and the filtrate was sent to a sewage workshop for deep treatment. The filter residue was dried in a dryer at 260°C for 2 h. After drying, it was placed in a muffle furnace and calcined at 1150±50°C for 30 min to obtain 4.43 g of elemental copper with a recovery rate of 83.1%.

[0014] Reaction phenomenon: white phosphorus quickly dissolves after being added to carbon disulfide. It is slowly added to the copper sulfate solution at a rate of 0.3 kg / min. It can be seen that as the reaction proceeds, the color of the solution (blue) gradually becomes lighter. First, red fine particles of copper appear at the bottom of the container or in the solution. As the reaction temperature increases, gray-black cuprous phosphide precipitates gradually appear. After adding potassium borohydride solution, the gray-black precipitate gradually reacts to form red fine particles of copper, which are filtered out and roasted to form copper blocks. Example 2

[0015] A method for harmlessly treating waste white phosphorus and recovering copper comprises the following steps: (1) At room temperature and pressure, weigh 21 g of copper sulfate pentahydrate (analytical grade, content greater than 99.0%) in a glass reactor, add water to 100 g, and stir until the copper sulfate pentahydrate is completely dissolved to obtain a copper sulfate solution with a mass concentration of 21%; (2) Weigh 3 g of carbon disulfide solution and add 1 g of white phosphorus, stirring thoroughly until the white phosphorus is completely dissolved to obtain a white phosphorus-carbon disulfide mixed solution; (3) under stirring, slowly adding the white phosphorus-carbon disulfide mixed solution to the copper sulfate solution at a dropping rate of 0.4 kg / min, and continuously stirring for 4 hours after the addition until the reaction is complete to obtain a reaction solution. During the reaction, the volatile carbon disulfide gas emitted is collected and treated; (4) 20 g of 5% potassium borohydride solution was added dropwise to the reaction solution at a dropping rate of 0.3 kg / min, and the reaction was continued with stirring for 1 h. After the reaction was completed, the mixture was allowed to stand for 3 h. After standing, the mixture was filtered and the filtrate was sent to a sewage workshop for deep treatment. The filter residue was dried in a dryer at 260 °C for 2 h. After drying, the residue was calcined in a muffle furnace at 1150±50 °C for 30 min to obtain 3.58 g of elemental copper with a recovery rate of 67.1%.

[0016] Reaction phenomenon: white phosphorus quickly dissolves after being added to carbon disulfide. It is slowly added dropwise to the copper sulfate solution at a rate of 0.4 kg / min. It can be seen that as the reaction proceeds, the color of the solution (blue) gradually becomes lighter. Large red copper particles first appear at the bottom of the container or in the solution. As the reaction temperature increases, gray-black cuprous phosphide precipitates gradually appear. The reaction time is relatively long. After adding potassium borohydride solution, the gray-black precipitate gradually reacts slowly to form red fine particles of copper element, which are filtered out and roasted to form copper blocks, but the yield is not high. Example 3

[0017] A method for harmlessly treating waste white phosphorus and recovering copper comprises the following steps: (1) At room temperature and pressure, weigh 21 kg of copper sulfate pentahydrate (analytical grade, content greater than 99.0%) into a glass reactor, add water to 100 kg, turn on a stirring device and stir until the copper sulfate pentahydrate is completely dissolved to obtain a copper sulfate solution with a mass concentration of 21%; (2) Weigh 3 kg of carbon disulfide solution and add 1 kg of white phosphorus, stirring thoroughly until the white phosphorus is completely dissolved to obtain a white phosphorus-carbon disulfide mixed solution; (3) under stirring, the white phosphorus-carbon disulfide mixed solution is slowly added dropwise to the copper sulfate solution at a dropping rate of 0.3 kg / min, and after the addition is completed, stirring is continued for 3 hours until the reaction is complete to obtain a reaction solution. During the reaction, the volatile carbon disulfide gas emitted is collected and treated; (4) 20 kg of 5% potassium borohydride solution was added to the reaction solution at a dropping rate of 0.3 kg / min, and the reaction was continued with stirring for 1 h. After the reaction was completed, the solution was allowed to stand for 3 h. After standing, the solution was filtered and the filtrate was sent to a sewage workshop for deep treatment. The filter residue was dried in a dryer at 300 °C for 2 h. After drying, the residue was calcined in a muffle furnace at 1150±50 °C for 30 min to obtain 3.89 kg of elemental copper with a recovery rate of 72.9%.

[0018] Reaction phenomenon: white phosphorus quickly dissolves after being added to carbon disulfide. It is slowly added dropwise to the copper sulfate solution at a rate of 0.3 g / min. It can be seen that as the reaction proceeds, the color of the solution (blue) gradually becomes lighter. First, red fine particles of copper appear at the bottom of the container or in the solution. As the reaction temperature increases, gray-black cuprous phosphide precipitates gradually appear. After adding potassium borohydride solution, the gray-black precipitate gradually reacts to form red fine particles of copper, which are filtered out and roasted to form copper blocks. Example 4

[0019] A method for harmlessly treating waste white phosphorus and recovering copper comprises the following steps: (1) At room temperature and pressure, weigh 42 kg of copper sulfate pentahydrate (analytical grade, content greater than 99.0%) into a glass reactor, add water to 200 kg, turn on a stirring device and stir until the copper sulfate pentahydrate is completely dissolved to obtain a copper sulfate solution with a mass concentration of 21%; (2) Weigh 5 kg of carbon disulfide solution and add 2 kg of white phosphorus, and stir thoroughly until the white phosphorus is completely dissolved to obtain a white phosphorus-carbon disulfide mixed solution; (3) under stirring, the white phosphorus-carbon disulfide mixed solution is slowly added dropwise to the copper sulfate solution at a dropping rate of 0.3 kg / min, and after the addition is completed, stirring is continued for 3 hours until the reaction is complete to obtain a reaction solution. During the reaction, the volatile carbon disulfide gas emitted is collected and treated; (4) 40 kg of 5% potassium borohydride solution was added to the reaction solution at a dropping rate of 0.3 kg / min, and the reaction was continued with stirring for 1 h. After the reaction was completed, the solution was allowed to stand for 3 h. After standing, the solution was filtered and the filtrate was sent to a sewage workshop for deep treatment. The filter residue was dried in a dryer at 300 °C for 2 h. After drying, the residue was calcined in a muffle furnace at 1150±50 °C for 30 min to obtain 3.78 kg of elemental copper with a recovery rate of 70.9%.

[0020] Reaction phenomenon: white phosphorus quickly dissolves after being added to carbon disulfide. It is slowly added dropwise to the copper sulfate solution at a rate of 0.3 g / min. It can be seen that as the reaction proceeds, the color of the solution (blue) gradually becomes lighter. First, red fine particles of copper appear at the bottom of the container or in the solution. As the reaction temperature increases, gray-black cuprous phosphide precipitates gradually appear. After adding potassium borohydride solution, the gray-black precipitate gradually reacts to form red fine particles of copper, which are filtered out and roasted to form copper blocks.

[0021] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for harmlessly treating waste white phosphorus and recovering copper, characterized in that: The following steps are involved: (1) dissolving copper sulfate pentahydrate in water to prepare a copper sulfate solution with a mass concentration of 21%; (2) dissolving 1 part by mass of waste white phosphorus in 2 to 4 parts by mass of carbon disulfide to prepare a white phosphorus-carbon disulfide mixed solution; (3) slowly adding the white phosphorus-carbon disulfide mixed solution prepared in step (2) to the copper sulfate solution prepared in step (1), wherein the mass ratio of white phosphorus to copper sulfate solution is 1:100, and stirring until the reaction is complete to obtain a reaction solution; (4) adding a 5% potassium borohydride solution to the reaction solution of step (3) and stirring, wherein the amount of the potassium borohydride solution added is 20 to 30 times the mass of the white phosphorus; (5) After the reaction is completed, the mixture is allowed to stand and filtered, and the filtrate is sent to a sewage treatment station for treatment. The filter residue is dried and roasted to recover the copper element.

2. The method for harmlessly treating waste white phosphorus and recovering copper according to claim 1, characterized in that: In step (3), the rate of adding the white phosphorus-carbon disulfide mixture is 0.1 to 0.3 kg / min.

3. The method for harmlessly treating waste white phosphorus and recovering copper according to claim 1, characterized in that: In step (3), the volatile carbon disulfide gas emitted during the reaction is collected and treated.

4. The method for harmlessly treating waste white phosphorus and recovering copper according to claim 1, characterized in that: In step (4), the addition rate of potassium borohydride solution is 0.1 to 0.3 kg / min.

5. The method for harmlessly treating waste white phosphorus and recovering copper according to claim 1, characterized in that: The drying in step (5) is carried out at a temperature of 260-300°C for 2 h.

6. The method for harmlessly treating waste white phosphorus and recovering copper according to claim 5, characterized in that: The calcination in step (5) is carried out in a muffle furnace at 1100-1200° C. for 30 min.