阅读说明：本技术 一种高温相转化法处理熔盐氯化废渣的方法 (Method for treating fused salt chlorination waste residue by high-temperature phase conversion method ) 是由 陈凤 郑富强 王帅 苗庆东 郭宇峰 朱福兴 邱冠周 杨凌志 姚洪国 侯晓磊 于 2020-08-13 设计创作，主要内容包括：本发明公开了一种高温相转化法处理熔盐氯化废渣的方法,包括以下步骤:(1)熔盐氯化废渣出炉后,在保温下进行固液分离,获得未反应的残渣返回熔盐氯化炉中；(2)获得滤液输送至已预热的高温反应炉中,升温至设定温度,然后加入添加剂进行反应,与氯化钙、氯化镁难挥发氯化盐生成沉淀；(3)将反应产物进行固液分离,获得滤液即为氯化钠为主的熔盐,循环进入氯化炉；沉淀排渣后,可用作建材原料或制磷肥原料。本发明的高温相转化法处理熔盐氯化废渣的方法,采用火法冶金方法处理熔盐氯化废渣,结合生产现状,生产效率比水溶法高,从熔盐氯化废渣中获得新熔盐的简洁方法；能实现熔盐的循环利用,大幅降低熔盐氯化工艺持续补充新盐的成本问题。(The invention discloses a method for treating fused salt chlorination waste residue by a high-temperature phase conversion method, which comprises the following steps of (1) after the fused salt chlorination waste residue is taken out of a furnace, carrying out solid-liquid separation at the constant temperature to obtain unreacted residue to return to the fused salt chlorination furnace; (2) conveying the obtained filtrate to a preheated high-temperature reaction furnace, heating to a set temperature, adding an additive for reaction, and generating precipitates with calcium chloride and magnesium chloride salt which are difficult to volatilize; (3) carrying out solid-liquid separation on the reaction product to obtain filtrate, namely molten salt mainly containing sodium chloride, and circularly entering a chlorination furnace; after sediment and slag discharge, the product can be used as a building material or a phosphate fertilizer raw material. According to the method for treating the waste molten salt chlorination residues by the high-temperature phase conversion method, the waste molten salt chlorination residues are treated by a pyrometallurgical method, the production efficiency is higher than that of a water-soluble method by combining the current production situation, and a simple method for obtaining new molten salt from the waste molten salt chlorination residues is provided; the recycling of the molten salt can be realized, and the cost problem of continuously supplementing new salt in the molten salt chlorination process is greatly reduced.)

1. A method for treating molten salt chlorination waste residue by a high-temperature phase conversion method comprises the following steps:

(1) after the waste slag of the molten salt chlorination is taken out of the furnace, carrying out solid-liquid separation at the constant temperature to obtain unreacted slag, and returning the unreacted slag to the molten salt chlorination furnace;

(2) conveying the filtrate obtained in the step (1) to a preheated high-temperature reaction furnace, heating to a set temperature, adding an additive, reacting, and generating a precipitate with calcium chloride and magnesium chloride salt which are difficult to volatilize;

(3) carrying out solid-liquid separation on the reaction product obtained in the step (2) to obtain filtrate, namely molten salt mainly containing sodium chloride, and circularly entering a chlorination furnace; after sediment and slag discharge, the product can be used as a building material or a phosphate fertilizer raw material.

2. The method for treating the waste slag of the molten salt chlorination through the high-temperature phase conversion method according to the claim 1, wherein in the step (2), the obtained filtrate is mainly the chloride which is difficult to volatilize.

3. The method for treating the waste slag of the molten salt chlorination through the high-temperature phase transformation method according to claim 1, wherein in the step (2), the preheating temperature of the high-temperature reaction furnace is 700-850 ℃.

4. The method for treating the waste slag of the molten salt chlorination through the high-temperature phase inversion method according to claim 1, wherein in the step (2), the reaction set temperature is 850-1200 ℃, and the reaction time is 30-180 min.

5. The method for treating the waste slag of the molten salt chlorination through the high-temperature phase transformation method according to the claim 1, wherein in the step (2), the additives are sodium silicate, sodium phosphate and other alkali metal silicates and alkali metal phosphates; the molar weight of the additive is 0-2 times of the total molar weight of calcium chloride and magnesium chloride in the chloride filtrate.

6. The method for treating the waste slag of the molten salt chlorination through the high-temperature phase inversion method according to the claim 1, wherein in the step (1) and the step (3), the solid-liquid separation mode is pressure filtration, vacuum filtration or centrifugal separation filtration; the solid-liquid separation medium is porous high-temperature ceramic.

Technical Field

The invention belongs to the technical field of titanium metallurgy solid waste utilization, and particularly relates to a method for treating molten salt chlorination waste residues by a high-temperature phase transformation method.

Background

Titanium is known as the strategic metal and the "third metal". The high-end product of titanium, namely metallic titanium and titanium white by a chlorination process, has important strategic significance for developing national economy and consolidating national safety, and is important embodiment of comprehensive national strength. At present, titanium products in China mainly comprise medium and low-end sulfuric acid process titanium dioxide products, and the supply of high-end titanium products is seriously insufficient. In order to enhance the comprehensive national force of China, the development of high-end titanium products must be accelerated.

Production of high-end titanium products requires the use of titanium tetrachloride (TiCl)₄) Is an intermediate. TiCl (titanium dioxide)₄Obtaining sponge titanium (Ti) by reduction or obtaining titanium dioxide (TiO) by chlorination process by oxidation₂). At present, TiCl is industrially prepared₄The method mainly comprises a boiling chlorination method and a molten salt chlorination method.

The reserves of titanium resources in China are rich, but the resources are not good enough, mainly rock-mineral type ilmenite is taken as the main resource, the content of calcium and magnesium impurities is high, and the content of calcium and magnesium CaO + MgO in the titanium resources in Panxi area is more than or equal to 5-10%. Calcium and magnesium impurities are easy to generate low-melting-point and high-boiling-point chlorides in the boiling chlorination process, and the low-melting-point and high-boiling-point chlorides are bonded with carbon particles and mineral particles to form blocks after accumulation, so that the fluidization state in the furnace is damaged, and the production efficiency is influenced. The existing boiling chlorination production lines in China cannot adopt high-calcium magnesium titanium resources in China to prepare high-end titanium products at present, and production raw materials mainly depend on import.

China titanium sponge and titanium white production enterprises adopting chlorination method for producing TiCl by using molten salt chlorination method when China high-calcium magnesium titanium resources are utilized₄. The initial salt is usually selected from sodium potassium salt or high sodium salt. During the production of molten salt chlorination, a molten salt system gradually deteriorates, the molten salt chlorination process is influenced, normal production is damaged, waste salt needs to be discharged periodically, new molten salt needs to be supplemented continuously, and the properties of the molten salt system are improved. The fused salt chlorination method has no harsh requirements on furnace burden and is suitable for high calcium, magnesium and titanium resources in China; but the biggest defect is that a large amount of fused salt chlorination waste residues are generated, and the waste residue amount can reach 300-400 Kg/ton TiCl₄。

The waste slag of fused salt chlorination has complex components, the main fused salt phase is NaCl and contains various chlorides, unreacted oxides, coke and the like. Wherein CaCl₂、MgCl₂And when chlorides are mixed with NaCl, the recovery and the treatment are difficult, and the direct stacking or the landfill causes environmental problems of underground water pollution, salinized soil pollution and the like.

At present, the research on treatment and recycling of the fused salt chlorination waste residue at home and abroad is less, and the main treatment method is a water-soluble method. According to the order of processing water-soluble chloride, the method can be divided into a front-end water-soluble method and a rear-end water-soluble method, and the front-end water-soluble method is more researched. The front-end water-soluble method is characterized in that after molten salt chlorination waste residues are dissolved in water, soluble chloride-containing filtrate and insoluble solid particle filter residues are separated, the filter residues are used for stockpiling, and recycling research mainly aims at the soluble chloride salt filtrate, but at present, a reasonable and efficient treatment method is not available. The rear-end water-soluble method is to carry out heat preservation, standing and layering when the waste molten salt is discharged from the furnace and cooled, remove a part of impurities as much as possible, and then carry out water-soluble method treatment to recover soluble chloride. The method has the disadvantages of complicated treatment process, long impurity removal process and difficult industrial application. More importantly, the layered design of the method is ideal, the upper layer interface, the middle layer interface and the lower layer interface are mixed in actual production, and the molten salt chlorination waste residue discharged in actual production cannot be effectively treated.

From the aspect of resource characteristics, China is more suitable for realizing high-end utilization of titanium resources by adopting a molten salt chlorination method, but the problem of treatment of a large amount of molten salt chlorination waste residues needs to be solved urgently, the fundamental method for solving the problem is to realize cyclic utilization of NaCl molten salt, and the key is to remove CaCl in the molten salt chlorination waste residues₂、MgCl₂And the like, the chloride is difficult to treat. At present, the treatment and utilization process of the waste slag of the molten salt chlorination at home and abroad is complex, the amount of waste water is large, the industrial application difficulty is large, and a large amount of waste salt is not effectively recovered.

Disclosure of Invention

The invention aims to provide a method for treating fused salt chlorination waste residue by a high-temperature phase conversion method with high production efficiency, and can realize the recycling of fused salt.

The method for treating the waste slag of the molten salt chlorination by the high-temperature phase conversion method comprises the following steps:

(1) after the waste slag of the molten salt chlorination is taken out of the furnace, carrying out solid-liquid separation at the constant temperature to obtain unreacted slag, and returning the unreacted slag to the molten salt chlorination furnace;

(2) conveying the filtrate obtained in the step (1) to a preheated high-temperature reaction furnace, heating to a set temperature, adding an additive, reacting, and generating a precipitate with calcium chloride and magnesium chloride salt which are difficult to volatilize;

(3) carrying out solid-liquid separation on the reaction product obtained in the step (2) to obtain filtrate, namely molten salt mainly containing sodium chloride, and circularly entering a chlorination furnace; after sediment and slag discharge, the product can be used as a building material or a phosphate fertilizer raw material.

The filtrate obtained in the step (2) is mainly a chloride salt which is difficult to volatilize. The preheating temperature of the high-temperature reaction furnace is 700-850 ℃, the reaction set temperature is 850-1200 ℃, and the reaction time is 30-180 min.

In the step (2), the additive includes, but is not limited to, alkali metal silicate, alkali metal phosphate, preferably sodium silicate or sodium phosphate; the molar weight of the additive is 0-2 times, preferably 0.6-1 times of the total molar weight of calcium chloride and magnesium chloride in the chloride filtrate.

In the step (1) and the step (3), the solid-liquid separation mode is pressure filtration, vacuum filtration or centrifugal separation filtration; the solid-liquid separation medium is porous high-temperature ceramic.

The principle of the invention is as follows:

the invention produces TiCl by a molten salt chlorination method₄The generated fused salt chlorination waste residue is used as a raw material, and a high-temperature phase conversion method is adopted to remove impurities and recycle the fused salt. The liquid-solid phase conversion is carried out at high temperature by utilizing the physicochemical property difference of different components, and the concept of impurity high-temperature phase classification separation is adopted, so that the technical scheme of impurity solid-liquid separation is provided. According to the scheme, through high-temperature chemical precipitation of impurities, the high-melting-point characteristic of precipitates is utilized to realize impurity separation to obtain new molten salt, and the new molten salt is circulated to enter a molten salt chlorination process. The chemical reactions mainly involved in the invention are as follows:

3CaCl₂+2(PO₄)³-＝Ca₃(PO₄)₂↓+6Cl-

3MgCl₂+2(PO₄)^3-＝Mg₃(PO₄)₂↓+6Cl^-

the invention has the beneficial effects that:

(1) the method for treating the molten salt chlorination waste residue by the high-temperature phase conversion method adopts a pyrometallurgical method to treat the molten salt chlorination waste residue, combines the current production situation, has higher production efficiency than a water-soluble method, and is a simple method for obtaining new molten salt from the molten salt chlorination waste residue. The recycling of the molten salt can be realized, and the cost problem of continuously supplementing new salt in the molten salt chlorination process is greatly reduced. Compared with a water-soluble method, the method does not generate a large amount of chlorine-containing salt-containing wastewater, and is favorable for solving the problem of secondary pollution caused by the conventional waste residue disposal.

(2) The process flow of the method for treating the waste slag of the molten salt chlorination by the high-temperature phase conversion method only relates to a one-step high-temperature method, and impurities can be separated from the lower part of a reactor in a precipitation mode in one high-temperature reactor. Except that the new salt phase is a main product, the new salt phase can be recovered after precipitation and slag discharge and can be used as a building material raw material or a phosphoric acid preparation raw material. The overall process flow has the characteristics of recycling, cleanness and environmental protection.

Drawings

FIG. 1 is a process flow diagram for treating waste slag of molten salt chlorination by the high-temperature phase conversion method.

FIG. 2 is a schematic view of the apparatus for treating waste slag of molten salt chlorination by high temperature phase inversion method.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without any creative work based on the embodiments of the present invention belong to the protection scope of the present invention.

The process flow diagram of the invention is shown in fig. 1, and the equipment schematic diagram is shown in fig. 2, specifically shown as an embodiment.