A method for processing waste by-products in a full-process titanium sponge production process

Abstract

The present application relates to chemical processing technical field, concretely for a kind of waste by-product processing method in whole-process titanium sponge production process, comprising: waste sulfuric acid and waste molten salt are generated hydrogen chloride gas by chemical reaction, the gas is used to prepare pure hydrochloric acid.Solids generated by reaction are beaten, and the main component of solution is sodium sulfate and ferrous sulfate, after oxidation by chlorine, ferrous sulfate is converted into ferric sulfate, and then by neutralization, ferric sulfate is precipitated, and finally liquid is sodium sulfate solution.Sodium sulfate is crystallized out by constant-temperature crystallization method, high-purity sodium sulfate is obtained, which is suitable for MVR production and sale, etc.Solids separated by beating are mainly high-titanium-containing slag and petroleum coke, which are used for molten salt chlorination production after drying.The present application realizes waste by-product processing of whole-process titanium sponge production process, reduces production operating cost, improves the use value of waste by-product, promotes the application of molten salt chlorination in titanium sponge production, and avoids the elimination of molten salt chlorination furnace due to waste by-product processing problems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical processing, in particular to a treatment method for waste by-products in a full-process titanium sponge production process. BACKGROUND

[0002] In the existing full-process titanium sponge production process, mainly involves chlorination, electrolysis, reduction and distillation four sections, the present application proposes a method for molten salt chlorination process. Because molten salt chlorination generates a large amount of chlorinated waste salt in the production process, the chlorinated waste salt is mainly treated by neutralization, and a large amount of solid waste residue is generated after treatment, which also involves a series of environmental problems, restricting economic development. At present, a method of water quenching molten salt and then neutralizing with scandium is proposed, which also produces a large amount of neutralization residue, and cannot solve the problem of waste molten salt treatment from the root. In the electrolysis section, the main waste by-products are concentrated sulfuric acid, and a certain amount of waste acid is generated due to the need to dry chlorine. The concentration of waste acid discharged is about 90-93%. Due to the special chemical properties of waste sulfuric acid, neutralization is difficult, and new waste water is generated after dilution. The present application mainly proposes a new waste by-product treatment method, which can reduce the amount and cost of neutralization waste residue by coordinating the export of waste by-products. In general, the main problems existing in the current full-process titanium sponge (molten salt chlorination) production are: large amount of solid residue, high neutralization cost, large amount of tail gas absorption liquid, and low resource recovery rate. SUMMARY

[0003] The present application relates to the technical field of chemical processing, in particular to a treatment method for waste by-products in a full-process titanium sponge production process.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] A treatment method for waste by-products in a full-process titanium sponge production process, which recycles waste by-product resources, and the specific steps are as follows:

[0006] S10: reacting the waste molten salt generated by molten salt chlorination with the waste sulfuric acid generated by magnesium electrolysis, absorbing the generated HCl gas, and finally obtaining an HCl solution with a concentration of ≥30%;

[0007] S20: beating the solid mixture generated by the reaction, and then using a centrifuge for solid-liquid separation to obtain a liquid containing sodium sulfate and ferrous sulfate, and a solid residue containing high-titanium slag and petroleum coke, and drying the solid residue and returning it to the molten salt chlorination furnace;

[0008] S30: After obtaining a liquid containing sodium sulfate and ferrous sulfate, it enters the oxidation section, where chlorine gas contained in the molten salt chlorination tail gas is used for oxidation to oxidize ferrous sulfate to ferric sulfate.

[0009] S40: After oxidation is complete, caustic soda is added to ferric sulfate to remove Fe. 3+ The process is converted into precipitation separation, separating sodium sulfate solution and ferric hydroxide solid. The ferric hydroxide solid is sold as a pelleting additive.

[0010] S50: Sodium sulfate solution is crystallized. The crystallization process first involves evaporating and concentrating the sodium sulfate solution. When the concentration reaches 25-30%, it is crystallized at a constant temperature to precipitate sodium sulfate crystals. Finally, the remaining liquid from the crystallization is returned to the pulping process for recycling.

[0011] Preferably, the concentration of the waste sulfuric acid solution in step S10 is ≥80%.

[0012] Preferably, the waste molten salt in step S10 consists of TiO2 3.13%, C 3.53%, NaCl 48.15%, FeCl2 16.55%, SiO2 4.83%, AlCl3 7.15%, CaCl2 2.22%, MgCl2 8.17%, KCl 0.56%, and residual impurities.

[0013] Preferably, in step S20, the high-titanium slag and petroleum coke solids are dried and reused, and are mixed with the high-titanium slag with larger particle size.

[0014] Preferably, the solid slag in step S20 consists of CuO 0.042%, MgO 1.624%, Al2O3 0.055%, SiO2 0.165%, SO3 79.727%, Cl 0.211%, Cr2O3 0.19%, TiO2 0.074%, MnO 0.055%, Fe2O3 17.785%, and remaining impurities.

[0015] Preferably, in step S30, the residual chlorine gas in the tail gas is used to treat Fe. 2+ It undergoes oxidation to replace the chlorine absorption liquid.

[0016] Preferably, in step S40, caustic soda is used to react Fe... 3+ The precipitate formed, and the final residue contained sodium sulfate solution.

[0017] Preferably, the concentration of sodium sulfate after evaporation and concentration in step S50 is 25%-30%.

[0018] Preferably, the isothermal crystallization temperature in step S50 is 25℃±5℃.

[0019] Preferably, the optimal temperature for isothermal crystallization in step S50 is 25°C.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This method for treating waste byproducts in the entire sponge titanium production process involves reacting waste sulfuric acid and waste molten salt to generate hydrogen chloride gas, which is used to prepare pure hydrochloric acid. The resulting solid slag is pulped, and the solution mainly consists of sodium sulfate and ferrous sulfate. After oxidation with chlorine gas, the ferrous sulfate is converted to ferric sulfate, which is then neutralized to precipitate, resulting in a sodium sulfate solution. Sodium sulfate is then crystallized out using a constant-temperature crystallization method to obtain high-purity sodium sulfate, suitable for use in MVR production and for sale. The solid slag separated from the pulping mainly consists of high-titanium slag and petroleum coke, which is dried and used in molten salt chlorination production. According to this invention, waste byproduct treatment of the entire sponge titanium production process is achieved, reducing production and operating costs, increasing the utilization value of waste byproducts, promoting the application of molten salt chlorination in sponge titanium production, and avoiding the elimination of molten salt chlorination furnaces due to waste byproduct treatment issues.

[0022] 2. Waste treatment methods in the whole process of sponge titanium production: (1) Reduce the discharge of solid slag. After the waste molten salt is reacted, dissolved and crystallized, a large amount of solid slag is reused, which greatly reduces the amount of solid slag discharged; (2) Reduce the cost of waste treatment. Through waste recycling, a portion is sold or reused to achieve cost reduction; (3) Reduce the amount of tail gas absorbent liquid. The oxidation section will consume some of the chlorine in the tail gas, reducing the replenishment of tail gas absorbent liquid. Under normal production conditions, the addition of chlorine absorbent liquid can be basically achieved. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are explained in detail together with the embodiments of the invention, but do not constitute a limitation thereof.

[0024] Figure 1 This is a schematic diagram of the waste byproduct treatment process in the entire process of sponge titanium production according to the present invention. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] A method for handling waste materials during the entire process of sponge titanium production, comprising the following steps:

[0028] S10: The waste molten salt generated from molten salt chlorination is reacted with the waste sulfuric acid generated from magnesium electrolysis. Before the reaction, the waste sulfuric acid with a concentration of 90% is diluted to 70%, and the generated HCl gas is absorbed. Finally, the concentration of HCl solution can be ≥30%. The residue after the reaction is a solid-liquid mixture, and some hydrogen chloride gas is converted into solution residue.

[0029] S20: The solid mixture generated by the reaction is pulped, and then the solid and liquid are separated by a centrifuge to obtain a liquid containing sodium sulfate, ferrous sulfate and ferrous chloride, and a solid containing high titanium slag and petroleum coke. The solid slag is dried and returned to the molten salt chlorination furnace.

[0030] S30: After obtaining a liquid containing sodium sulfate, ferrous sulfate and ferrous chloride, it enters the oxidation section, where chlorine gas contained in the molten salt chlorination tail gas is used for oxidation, wherein ferrous sulfate is oxidized to ferric sulfate and ferrous chloride is oxidized to ferric chloride.

[0031] S40: After oxidation is complete, add caustic soda to remove Fe. 3+ The process is converted into precipitation separation, separating a solution containing sodium sulfate and sodium chloride, as well as solid ferric hydroxide. After washing with water, the total iron content of the solid ferric hydroxide is about 60%.

[0032] S50: Sodium sulfate solution is crystallized. The crystallization process first involves evaporating and concentrating the sodium sulfate solution. When the concentration reaches 25-30%, it is crystallized at a constant temperature of 25°C to precipitate sodium sulfate crystals with a purity of about 85%. Finally, the remaining liquid from the crystallization is returned to the pulping process for recycling.

[0033] Example 2

[0034] A method for handling waste materials during the entire process of sponge titanium production, comprising the following steps:

[0035] S10: The waste molten salt generated from molten salt chlorination is reacted with the waste sulfuric acid generated from magnesium electrolysis. Before the reaction, the 90% concentration waste sulfuric acid is diluted to 80%, and the generated HCl gas is absorbed. Finally, an HCl solution with a concentration of ≥30% can be obtained. The residue after the reaction is solid.

[0036] S20: The solid mixture generated by the reaction is pulped, and then the solid and liquid are separated by a centrifuge to obtain a liquid containing sodium sulfate and ferrous sulfate, and a solid containing high titanium slag and petroleum coke. The solid slag is dried and returned to the molten salt chlorination furnace.

[0037] S30: After obtaining a liquid containing sodium sulfate and ferrous sulfate, it enters the oxidation section, where it is oxidized using chlorine gas contained in the molten salt chlorination tail gas, wherein ferrous sulfate is oxidized to ferric sulfate.

[0038] S40: After oxidation is complete, add caustic soda to remove Fe. 3+ The process is converted into precipitation separation, separating out a sodium sulfate solution and ferric hydroxide solid. After washing with water, the ferric hydroxide solid has a total iron content of about 60%.

[0039] S20: Sodium sulfate solution is crystallized. The crystallization process first involves evaporating and concentrating the sodium sulfate solution. When the concentration reaches 25-30%, it is crystallized at a constant temperature of 25°C to precipitate sodium sulfate crystals with a purity of about 95%. Finally, the remaining liquid from the crystallization is returned to the pulping process for recycling.

[0040] Example 3

[0041] A method for handling waste materials during the entire process of sponge titanium production, comprising the following steps:

[0042] S10: The waste molten salt generated from molten salt chlorination is reacted with the waste sulfuric acid generated from magnesium electrolysis. The waste sulfuric acid with a concentration of 90% before the reaction is not diluted. The generated HCl gas is absorbed, and finally an HCl solution with a concentration of ≥30% can be obtained. The residue after the reaction is solid.

[0043] S20: The solid mixture generated by the reaction is pulped, and then the solid and liquid are separated by a centrifuge to obtain a liquid containing sodium sulfate and ferrous sulfate, and a solid containing high titanium slag and petroleum coke. The solid slag is dried and returned to the molten salt chlorination furnace.

[0044] S30: After obtaining a liquid containing sodium sulfate and ferrous sulfate, it enters the oxidation section, where it is oxidized using chlorine gas contained in the molten salt chlorination tail gas, wherein ferrous sulfate is oxidized to ferric sulfate.

[0045] S40: After oxidation is complete, add caustic soda to remove Fe. 3+ The process is converted into precipitation separation, separating out a sodium sulfate solution and ferric hydroxide solid. After washing with water, the ferric hydroxide solid has a total iron content of about 60%.

[0046] S50: Sodium sulfate solution is crystallized. The crystallization process first involves evaporating and concentrating the sodium sulfate solution. When the concentration reaches 25-30%, it is crystallized at a constant temperature of 25°C to precipitate sodium sulfate crystals with a purity of about 98%. Finally, the remaining liquid from the crystallization is returned to the pulping process for recycling.

[0047] The three embodiments described above involve a chemical reaction between waste sulfuric acid and waste molten salt to generate hydrogen chloride gas, which is used to prepare pure hydrochloric acid. The resulting solid slag is pulped, and the solution mainly consists of sodium sulfate and ferrous sulfate. After oxidation with chlorine gas, the ferrous sulfate is converted to ferric sulfate, which is then neutralized to precipitate, resulting in a final liquid sodium sulfate solution. Sodium sulfate is then crystallized out using a constant-temperature crystallization method to obtain high-purity sodium sulfate, suitable for use in MVR production and for sale. The solid slag separated from the pulping mainly consists of high-titanium slag and petroleum coke, which is dried and used in molten salt chlorination production. According to the embodiments of the present invention, a complete waste by-product treatment process for sponge titanium production is achieved, reducing production and operating costs, increasing the utilization value of waste by-products, promoting the application of molten salt chlorination in sponge titanium production, and avoiding the elimination of molten salt chlorination furnaces due to waste by-product treatment issues.

[0048] The experimental results of the three embodiments described above are summarized in the table below:

[0049] Spent sulphuric acid concentration Absorbed HCI concentration Total iron content of solid residue Sodium sulphate content Example 1 70％ ≥30％ 60％±5 85％ Example 2 80％ ≥30％ 60％±5 95％ Example 3 90％ ≥30％ 60％±5 98％

[0050] Example 4

[0051] Using the conditions described in Example 3, the sodium sulfate solution after the reaction was crystallized under different concentrations and isothermal conditions. Experiments revealed that at room temperature, evaporation and concentration to 20% yielded the best crystal quality, but the amount of crystals was insufficient for production needs. Therefore, overall, evaporation and concentration to 25%-30% at room temperature was most suitable for production. The results are shown in the table below:

[0052]

[0053] The present invention discloses a method for treating waste byproducts in the entire process of sponge titanium production. This method utilizes the reaction of waste molten salt and waste sulfuric acid to produce high-purity hydrogen chloride gas and sulfate solid slag. The hydrogen chloride gas is collected by absorption and high-concentration hydrochloric acid (≥30%) is prepared for sale. The sulfate mainly contains sodium sulfate and ferrous sulfate. It is first slurryed into an aqueous solution, and then the ferrous sulfate is oxidized to ferric sulfate by utilizing the chlorine gas mixed in with the molten salt chlorination tail gas. Then, sodium hydroxide is added to remove ferric ions, and finally, sulfuric acid solution is obtained by crystallization. A small portion is recycled to the MVR water treatment section, and the majority is crystallized and sold, realizing the comprehensive utilization of waste byproduct resources.

[0054] The waste treatment method of the whole process of sponge titanium production of the present invention is as follows: (1) Reduce the discharge of solid slag. After the waste molten salt is reacted, dissolved and crystallized, a large amount of solid slag is reused, which greatly reduces the amount of solid slag discharged; (2) Reduce the cost of waste treatment. Through the recycling of waste, a part of it is sold or reused to achieve the effect of cost reduction; (3) Reduce the amount of tail gas absorbent liquid. The oxidation section will consume part of the chlorine in the tail gas. Reduce the replenishment of tail gas absorbent liquid. Under normal production conditions, the addition of chlorine absorbent liquid can be basically achieved.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating waste materials during the entire process of sponge titanium production, characterized in that: The specific steps for recycling waste resources are as follows: S10: The waste molten salt generated from molten salt chlorination is reacted with the waste sulfuric acid generated from magnesium electrolysis, and the generated HCl gas is absorbed to finally obtain an HCl solution with a concentration of ≥30%; S20: The solid mixture generated by the reaction is pulped, and then the solid and liquid are separated by a centrifuge to obtain a liquid containing sodium sulfate and ferrous sulfate, and a solid slag containing high titanium slag and petroleum coke. The solid slag is dried and returned to the molten salt chlorination furnace. S30: After obtaining a liquid containing sodium sulfate and ferrous sulfate, it enters the oxidation section, where chlorine gas contained in the molten salt chlorination tail gas is used for oxidation to oxidize ferrous sulfate to ferric sulfate. S40: After oxidation is complete, caustic soda is added to ferric sulfate to remove Fe. 3+ The process is converted into precipitation separation, separating sodium sulfate solution and ferric hydroxide solid. The ferric hydroxide solid is sold as a pelleting additive. S50: Sodium sulfate solution is crystallized. The crystallization process first involves evaporating and concentrating the sodium sulfate solution. When the concentration reaches 25-30%, constant temperature crystallization is carried out to precipitate sodium sulfate crystals. Finally, the remaining liquid from the crystallization is returned to the pulping process for recycling. In step S10, the concentration of the waste sulfuric acid solution is ≥80%; The composition of the waste molten salt in step S10 is TiO2 3.13%, C 3.53%, NaCl 48.15%, FeCl2 16.55%, SiO2 4.83%, AlCl3 7.15%, CaCl2 2.22%, MgCl2 8.17%, KCl 0.56%, and residual impurities; In step S20, the high-titanium slag and petroleum coke solids are dried and reused, and are also mixed with the high-titanium slag with larger particle size for use. The solid slag in step S20 consists of CuO 0.042%, MgO 1.624%, Al2O3 0.055%, SiO2 0.165%, SO3 79.727%, Cl 0.211%, Cr2O3 0.19%, TiO2 0.074%, MnO 0.055%, Fe2O3 17.785%, and remaining impurities.

2. The method for treating waste materials during the entire process of sponge titanium production according to claim 1, characterized in that: In step S30, the residual chlorine gas in the tail gas is used to treat Fe. 2+ It undergoes oxidation to replace the chlorine absorption liquid.

3. The method for treating waste materials during the entire process of sponge titanium production according to claim 1, characterized in that: In step S40, caustic soda is used to react Fe... 3+ The precipitate formed, and the final residue contained sodium sulfate solution.

4. The method for treating waste materials during the entire process of sponge titanium production according to claim 1, characterized in that: In step S50, the concentration of sodium sulfate after evaporation and concentration is 25%-30%.

5. The method for treating waste materials during the entire process of sponge titanium production according to claim 1, characterized in that: The isothermal crystallization temperature in step S50 is 25℃±5℃.

6. The method for treating waste materials during the entire process of sponge titanium production according to claim 5, characterized in that: The optimal temperature for isothermal crystallization in step S50 is 25°C.

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