Method for curing calcium and magnesium impurities in titanium metallurgical molten salt slag by using curing agent

Abstract

The invention belongs to the technical field of titanium metallurgy solid waste utilization, and particularly relates to a method for curing calcium and magnesium impurities in titanium metallurgy molten salt slag through a curing agent. According to the method, the titanium metallurgical molten salt chlorination waste salt slag is used as a raw material, and calcium and magnesium impurities in the waste salt are promoted to generate liquid-solid phase conversion by using a sodium sulfate or sodium silicate high-temperature phase conversion method. And the calcium and magnesium impurities are precipitated, clarified and separated from the low-melting-point NaCl solution by utilizing the characteristics of high melting point and high density of the calcium and magnesium impurities, so that solid-liquid separation of the calcium and magnesium impurities and the NaCl solution is realized. Specifically, calcium and magnesium impurities react with a curing agent to generate high-melting-point and high-density calcium and magnesium impurities, and the calcium and magnesium impurities are subjected to nucleation, growth, precipitation and other processes, so that separation of the calcium and magnesium impurities and NaCl molten salt is finally realized, and the recyclable NaCl molten salt is obtained. And calcium and magnesium impurity tailings obtained after separation are subjected to water dissolution-hydrolysis treatment, an obtained NaCl solution enters a chlor-alkali process, and calcium and magnesium impurities are used as roadbed materials.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium metallurgical solid waste utilization, and specifically relates to a method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag by utilizing a solidifying agent. Background Art

[0002] At present, most titanium sponge and chloride titanium dioxide manufacturers use domestic high calcium magnesium titanium resources as raw materials to produce TiCl4 through molten salt chlorination. The molten salt chlorination method has relatively low requirements for furnace charge and can better adapt to the characteristics of my country's high calcium magnesium titanium resources. However, this method has an obvious disadvantage, that is, it will produce a large amount of molten salt chlorination waste salt slag. According to the current technical level, for every 10kt of titanium tetrachloride produced, about 11.7kt of waste salt will be discharged.

[0003] In the molten salt chlorination process, calcium and magnesium impurities in the raw materials will generate substances such as calcium chloride and magnesium chloride. These impurities will continue to accumulate in the salt solution, which will not only deteriorate the physical and chemical properties of the molten salt, but also seriously damage the chlorination reaction conditions in the furnace, thereby greatly affecting the production efficiency of molten salt chlorination. The composition of molten salt chlorination waste salt slag is extremely complex. The main molten salt phase is NaCl, and it also contains a variety of chlorides, unreacted oxides, and coke. Among them, chlorides such as CaCl2 and MgCl2 are mixed with NaCl, making recycling and treatment extremely difficult. If these waste salt slags are directly piled or landfilled, it will cause serious pollution to the ecological environment such as groundwater and soil.

[0004] At present, the main treatment methods for molten salt chlorination waste salt residue are deep burial and lime neutralization and then accumulation, but these methods cannot fundamentally solve the problem of its pollution to the environment. Although the water-soluble treatment can recover certain substances in the filtrate in a targeted manner, there are also many problems, such as the large amount of wastewater generated after treatment, the difficulty in removing impurities, the cumbersome and complicated process flow, and the lack of effective treatment methods for the generated filter residue.

[0005] Therefore, there is an urgent need to develop a method that can effectively solidify calcium and magnesium impurities in titanium metallurgical molten salt slag, so as to realize the resource utilization of calcium and magnesium impurities in titanium metallurgical molten salt slag, fundamentally solve the environmental pollution problem caused by waste salt slag, and improve the comprehensive utilization rate of resources.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent. The method uses a high-temperature phase transformation method to solidify calcium and magnesium impurities in titanium metallurgical molten salt slag, effectively avoiding the generation of a large amount of wastewater after impurity removal, environmental pollution of the process, and low resource utilization. The method can achieve overall recycling of molten salt chlorination waste slag at high temperature.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent, the specific steps are as follows:

[0010] Step 1, after the waste salt slag of the molten salt chlorination furnace is discharged from the furnace, it is kept at 420-700°C and subjected to the first solid-liquid separation to obtain a first filter residue and a first filtrate; the first filter residue is Ti residue and carbon powder, and the first filtrate is a mixed melt including NaCl, MgCl2, CaCl2, FeCl2, FeCl3, MnCl2, AlCl3, and TiCl4;

[0011] Step 2: the first filter residue is returned to the molten salt chlorination furnace to continue the reaction, and the first filtrate is sent to a high-temperature reaction furnace preheated to 420-700°C;

[0012] Step 3, first add a specific amount of curing agent into the high temperature reaction furnace, then heat the high temperature reaction furnace to 600-830°C at 5-25°C / min and keep it warm for 0.1-2h to obtain solution A; during the heating process, compressed air with a pressure of 0.01MPa-1.5MPa is passed into the first filtrate, and in the process of passing compressed air, volatile components such as manganese chloride, ferrous chloride, aluminum chloride, silicon tetrachloride, titanium tetrachloride, etc. in the first filtrate are fully volatilized; the curing agent is sodium sulfate or sodium silicate;

[0013] Step 4, heating the solution A to 835-1100° C. at 5-25° C. / min and keeping the temperature for 0.2-4 h to obtain a solid-liquid mixture B; during the heat preservation process, the curing agent fully reacts with the calcium chloride and magnesium chloride in the solution A to generate high melting point calcium sulfate and magnesium sulfate, or calcium silicate and magnesium silicate, and when the grains of calcium sulfate and magnesium sulfate, or calcium silicate and magnesium silicate are fully grown, they are fully separated from the NaCl melt and form a precipitate;

[0014] Step 5, subjecting the solid-liquid mixture B to a second solid-liquid separation to obtain a second filtrate and a second filter residue; the second filtrate is a NaCl melt, and the second filter residue is a sodium chloride salt residue containing calcium sulfate and magnesium sulfate; or a sodium chloride salt residue containing calcium silicate and magnesium silicate;

[0015] Step 6, sending the second filtrate to a molten salt chlorination furnace to continue the reaction; at the same time, cooling the second filter residue (slowly cooling to 98°C or below), and then subjecting it to a water dissolution-hydrolysis-standing-clarification treatment and then a third solid-liquid separation to obtain a salt solution and a third filter residue, thereby completing the solidification of calcium and magnesium impurities in the titanium metallurgical molten salt slag; the salt solution is a NaCl solution, and the third filter residue is a calcium sulfate or magnesium sulfate precipitate; or a calcium silicate or magnesium silicate precipitate, and the third filter residue is used as a roadbed paving material.

[0016] Specifically, in step 1, the first solid-liquid separation method is one of pressure filtration, vacuum filtration or centrifugal filtration, and the medium for the first solid-liquid separation is a porous high-temperature ceramic with a mesh density of 10ppi-600ppi.

[0017] Specifically, in step 3, the specific amount of curing agent is calculated as follows: first, the salt solution in the molten salt chlorination furnace is sampled and analyzed (or sampled and analyzed based on the previous bag of salt slag), and then the Ca content in the sample is calculated. 2+ Mg 2+ The ion mass percentage X (%) and Y (%) are used to calculate the amount of curing agent added in the high-temperature conversion process. The specific calculation formula is:

[0018]

[0019] Among them, 1.05 is the excess coefficient of the curing agent; 1000 is the calculation base for the mass of the salt slag to be converted, which is 1000kg; β is the molar mass of the curing agent, unit: g / mol; 40 is the molar mass of calcium ions, unit: g / mol; 24.3 is the molar mass of magnesium ions, unit: g / mol; X is the mass percentage of calcium ions in the salt slag to be converted; Y is the mass percentage of magnesium ions in the salt slag to be converted; M is the mass of the salt slag to be converted, unit: kg.

[0020] Specifically, in step 5, the second solid-liquid separation is performed by pressure filtration, vacuum filtration or centrifugal filtration, and the medium for the second solid-liquid separation is a porous high-temperature ceramic with a mesh density of 10ppi-600ppi.

[0021] Specifically, in step 6, a plate and frame filter press is used to perform a third solid-liquid separation.

[0022] In addition, the chemical reactions mainly involved in the present invention are as follows:

[0023] CaCl2+Na2SO4=2NaCl+CaSO4

[0024] MgCl2+Na2SO4=2NaCl+MgSO4

[0025] CaCl2+Na2SiO3=2NaCl+CaSiO3

[0026] MgCl2+Na2SiO3=2NaCl+MgSiO3

[0027]

[0028] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0029] The present invention uses titanium metallurgical molten salt chlorination waste salt slag as raw material, and uses sodium sulfate or sodium silicate high temperature phase conversion method to promote the liquid-solid phase transformation of calcium and magnesium impurities in the waste salt. The high melting point and high density characteristics of calcium and magnesium impurities are used to precipitate, clarify and separate with low melting point NaCl melt, so as to achieve solid-liquid separation of calcium and magnesium impurities and NaCl melt.

[0030] Specifically, the present invention generates high-melting-point and high-density calcium and magnesium impurities through the reaction of calcium and magnesium impurities with a curing agent. These calcium and magnesium impurities undergo processes such as nucleation, growth, and precipitation to ultimately separate the calcium and magnesium impurities from NaCl molten salt, thereby obtaining recyclable NaCl molten salt, which can be recycled into a molten salt chlorination process. The calcium and magnesium impurity tailings obtained after separation are treated by water dissolution-hydrolysis, and the obtained water-soluble product NaCl solution can enter the chlor-alkali process, while the calcium and magnesium impurities are used as roadbed materials.

[0031] In summary, the present invention realizes the resource utilization of calcium and magnesium impurities in titanium metallurgical molten salt slag, and completely solves the serious pollution problem of waste salt slag to ecological environment such as groundwater and soil. The molten salt chlorination waste salt slag is converted and treated by high temperature electrothermal metallurgical method, and the conversion tailings are treated by water dissolution-hydrolysis method, so that the production efficiency is high. This method not only realizes the resource utilization and harmless treatment of molten salt chlorination waste salt slag, but also greatly reduces the cost of continuous replenishment of new salt and disposal of waste salt in the molten salt chlorination process, and has good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0034] Figure 1 It is a process flow chart of the method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to the present invention;

[0035] Figure 2 The present invention is a schematic diagram of the solidification process of the method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent. DETAILED DESCRIPTION

[0036] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention as detailed in the appended claims.

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0038] Example 1

[0039] See also Figure 1 and 2 As shown, this embodiment provides a method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using sodium sulfate, and the specific steps are as follows:

[0040] Step 1: After the waste salt slag from the molten salt chlorination furnace is discharged from the furnace, it is kept at 420°C, and at the same time, the first solid-liquid separation is performed on a 10ppi porous high-temperature ceramic by pressure filtration, and the unreacted Ti residue and carbon powder are returned to the molten salt chlorination furnace, and the first filtrate is transported to a high-temperature reaction furnace preheated to 420°C;

[0041] Step 2: Add sodium sulfate to the high temperature reactor. The amount of sodium sulfate added depends on the Ca content in the sample. 2+ Mg 2+ The ion mass percentage X(%), Y(%), and the amount of anhydrous sodium sulfate added W are:

[0042]

[0043] Among them, 1.05 is the excess coefficient of sodium sulfate; 1000 is the calculation base number of the mass of the salt slag to be converted, which is 1000kg; 142 is the molar mass of sodium sulfate, unit: g / mol; 40 is the molar mass of calcium ion, unit: g / mol; 24.3 is the molar mass of magnesium ion, unit: g / mol; X is the mass percentage of calcium ion in the salt slag to be converted; Y is the mass percentage of magnesium ion in the salt slag to be converted; M is the mass of the salt slag to be converted, unit: kg;

[0044] The first filtrate is heated to 830°C and kept warm for 0.1h. During the heating process, compressed air is introduced into the salt solution to fully volatilize volatile components such as manganese chloride, ferrous chloride, aluminum chloride, silicon tetrachloride, titanium tetrachloride, etc. in the salt solution, and then a solution A is obtained;

[0045] Step 3, the solution A is further heated to 835°C and kept warm for 4 hours, until the sodium sulfate fully reacts with the calcium chloride and magnesium chloride to generate high melting point calcium sulfate and magnesium sulfate, and the grains of the calcium sulfate and magnesium sulfate are fully grown, fully separated from the sodium chloride salt solution and precipitated to obtain a solid-liquid mixture B;

[0046] Step 4: The solid-liquid mixture B is subjected to a second solid-liquid separation by pressure filtration in a 10 ppi porous high-temperature ceramic to obtain a molten salt mainly composed of NaCl and a second filter residue, and the molten salt is recycled into the molten salt chlorination process;

[0047] Step 5, first slowly cool the second filter residue to below 98°C, then perform water dissolution-hydrolysis-standing-clarification treatment, and then perform a third solid-liquid separation through a plate and frame filter press to obtain a filtered aqueous solution and a third filter residue, wherein the filtered aqueous solution is mainly a NaCl solution, and the NaCl solution is sent to the chlor-alkali process as a dissolved salt water after deep purification, and the third filter residue is a calcium sulfate and magnesium sulfate precipitate, which can be used as a roadbed paving material;

[0048] After deep purification, the NaCl solution is sent to the chlor-alkali process as dissolved brine. The main reactions are:

[0049]

[0050] In Example 1, it was found through testing that the present method was used to solidify calcium and magnesium impurities in titanium metallurgical molten salt slag, and the recovery rate of NaCl in the waste salt slag reached 81%.

[0051] Example 2

[0052] See also Figure 1 and 2 As shown, this embodiment provides a method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using sodium sulfate, and the specific steps are as follows:

[0053] Step 1: After the waste salt slag from the molten salt chlorination furnace is discharged from the furnace, it is kept at 700°C and vacuum filtered to perform the first solid-liquid separation under 600ppi porous high-temperature ceramics, and the unreacted Ti residue and carbon powder are returned to the molten salt chlorination furnace, and the first filtrate is transported to a high-temperature reaction furnace preheated to 700°C;

[0054] Step 2: Add sodium sulfate to the high temperature reactor. The amount of sodium sulfate added depends on the Ca content in the sample. 2+ Mg 2+ The ion mass percentage X(%), Y(%), and the amount of anhydrous sodium sulfate added W are:

[0055]

[0056] Among them, 1.05 is the excess coefficient of sodium sulfate; 1000 is the calculation base number of the mass of the salt slag to be converted, which is 1000kg; 142 is the molar mass of sodium sulfate, unit: g / mol; 40 is the molar mass of calcium ion, unit: g / mol; 24.3 is the molar mass of magnesium ion, unit: g / mol; X is the mass percentage of calcium ion in the salt slag to be converted; Y is the mass percentage of magnesium ion in the salt slag to be converted; M is the mass of the salt slag to be converted, unit: kg;

[0057] The first filtrate is heated to 600°C and kept warm for 2 hours. During the heating process, compressed air is introduced into the salt solution to fully volatilize volatile components such as manganese chloride, ferrous chloride, aluminum chloride, silicon tetrachloride, titanium tetrachloride, etc. in the salt solution, and then a solution A is obtained;

[0058] Step 3, the solution A is further heated to 1100°C and kept warm for 0.2h, until the sodium sulfate fully reacts with the calcium chloride and magnesium chloride to generate high melting point calcium sulfate and magnesium sulfate, and the grains of the calcium sulfate and magnesium sulfate are fully grown, fully separated from the sodium chloride salt solution and precipitated to obtain a solid-liquid mixture B;

[0059] Step 4: The solid-liquid mixture B is subjected to a second solid-liquid separation by vacuum filtration in a 600ppi porous high-temperature ceramic to obtain a filtrate, which is a molten salt mainly composed of NaCl, and a second filter residue, and the molten salt is circulated into the molten salt chlorination process;

[0060] Step 5, first slowly cool the second filter residue to below 98°C, then perform water dissolution-hydrolysis-standing-clarification treatment, and then perform a third solid-liquid separation through a plate and frame filter press to obtain a filtered aqueous solution and a third filter residue, wherein the filtered aqueous solution is mainly a NaCl solution, and the NaCl solution is sent to the chlor-alkali process as a dissolved salt water after deep purification, and the third filter residue is a calcium sulfate and magnesium sulfate precipitate, which can be used as a roadbed paving material;

[0061] After deep purification, the NaCl solution is sent to the chlor-alkali process as dissolved brine. The main reactions are:

[0062]

[0063] In Example 2, it was found through testing that the present method was used to solidify calcium and magnesium impurities in titanium metallurgical molten salt slag, and the recovery rate of NaCl in the waste salt slag reached 86.7%.

[0064] Example 3

[0065] See also Figure 1 and 2 As shown, this embodiment provides a method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using sodium sulfate, and the specific steps are as follows:

[0066] Step 1: After the waste salt slag from the molten salt chlorination furnace is discharged from the furnace, it is kept at 550°C, and the first solid-liquid separation is performed on a 300ppi porous high-temperature ceramic by centrifugal filtration, and the unreacted Ti residue and carbon powder are returned to the molten salt chlorination furnace, and the first filtrate is transported to a high-temperature reaction furnace preheated to 550°C;

[0067] Step 2: Add sodium sulfate to the high temperature reactor. The amount of sodium sulfate added depends on the Ca content in the sample. 2+ Mg 2+ The ion mass percentage X(%), Y(%), and the amount of anhydrous sodium sulfate added W are:

[0068]

[0069] Among them, 1.05 is the excess coefficient of sodium sulfate; 1000 is the calculation base number of the mass of the salt slag to be converted, which is 1000kg; 142 is the molar mass of sodium sulfate, unit: g / mol; 40 is the molar mass of calcium ion, unit: g / mol; 24.3 is the molar mass of magnesium ion, unit: g / mol; X is the mass percentage of calcium ion in the salt slag to be converted; Y is the mass percentage of magnesium ion in the salt slag to be converted; M is the mass of the salt slag to be converted, unit: kg;

[0070] The first filtrate is heated to 710°C and kept warm for 1 hour. During the heating process, compressed air is introduced into the salt solution to fully volatilize volatile components such as manganese chloride, ferrous chloride, aluminum chloride, silicon tetrachloride, titanium tetrachloride, etc. in the salt solution, and then a solution A is obtained;

[0071] Step 3, the solution A is further heated to 950°C and kept warm for 2 hours, until the sodium sulfate fully reacts with the calcium chloride and magnesium chloride to generate high melting point calcium sulfate and magnesium sulfate, and the calcium sulfate and magnesium sulfate grains are fully grown, fully separated from the sodium chloride salt solution and precipitated to obtain a solid-liquid mixture B;

[0072] Step 4: The solid-liquid mixture B is subjected to a second solid-liquid separation by centrifugal filtration on a 300 ppi porous high-temperature ceramic to obtain a molten salt mainly composed of NaCl and a second filter residue, and the molten salt is recycled into the molten salt chlorination process;

[0073] Step 5, first slowly cool the second filter residue to below 98°C, then perform water dissolution-hydrolysis-standing-clarification treatment, and then perform a third solid-liquid separation through a plate and frame filter press to obtain a filtered aqueous solution and a third filter residue, wherein the filtered aqueous solution is mainly a NaCl solution, and the NaCl solution is sent to the chlor-alkali process as a dissolved salt water after deep purification, and the third filter residue is a calcium sulfate and magnesium sulfate precipitate, which can be used as a roadbed paving material;

[0074] After deep purification, the NaCl solution is sent to the chlor-alkali process as dissolved brine. The main reactions are:

[0075]

[0076] In Example 3, it was found through testing that the present method was used to solidify calcium and magnesium impurities in titanium metallurgical molten salt slag, and the recovery rate of NaCl in the waste salt slag reached 84.9%.

[0077] Example 4

[0078] See also Figure 1 and 2 As shown, this embodiment provides a method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using sodium silicate, and the specific steps are as follows:

[0079] Step 1: After the waste salt slag from the molten salt chlorination furnace is discharged from the furnace, it is kept at 700°C and vacuum filtered to perform the first solid-liquid separation under 600ppi porous high-temperature ceramics, and the unreacted Ti residue and carbon powder are returned to the molten salt chlorination furnace, and the first filtrate is transported to a high-temperature reaction furnace preheated to 700°C;

[0080] Step 2: Add sodium silicate to the high temperature reactor. The amount of sodium silicate added is based on the Ca content in the sample. 2+ Mg 2+ The ion mass percentage X(%), Y(%), and the amount of sodium silicate added W are:

[0081]

[0082] Among them, 1.05 is the excess coefficient of sodium silicate; 1000 is the calculation base for the mass of salt slag to be converted, which is 1000kg; 122 is the molar mass of sodium silicate, unit: g / mol; 40 is the molar mass of calcium ion, unit: g / mol; 24.3 is the molar mass of magnesium ion, unit: g / mol; X is the mass percentage of calcium ion in the salt slag to be converted; Y is the mass percentage of magnesium ion in the salt slag to be converted; M is the mass of the salt slag to be converted, unit: kg;

[0083] The first filtrate is heated to 830°C and kept warm for 0.3h. During the heating process, compressed air is introduced into the salt solution to fully volatilize volatile components such as manganese chloride, ferrous chloride, aluminum chloride, silicon tetrachloride, titanium tetrachloride, etc. in the salt solution, and then a solution A is obtained;

[0084] Step 3, the solution A is further heated to 1000°C and kept warm for 0.2h, until the sodium silicate reacts fully with the calcium chloride and magnesium chloride to generate high melting point calcium silicate and magnesium silicate, and the grains of the calcium silicate and magnesium silicate are fully grown, fully separated from the sodium chloride salt solution and precipitated to obtain a solid-liquid mixture B;

[0085] Step 4: The solid-liquid mixture B is subjected to a second solid-liquid separation by vacuum filtration in a 600ppi porous high-temperature ceramic to obtain a filtrate, which is a molten salt mainly composed of NaCl, and a second filter residue, and the molten salt is circulated into the molten salt chlorination process;

[0086] Step 5, first slowly cool the second filter residue to below 98°C, then perform water dissolution-hydrolysis-standing-clarification treatment, and then perform a third solid-liquid separation through a plate and frame filter press to obtain a filtered aqueous solution and a third filter residue, wherein the filtered aqueous solution is mainly a NaCl solution, and the NaCl solution is sent to the chlor-alkali process as a dissolved salt water after deep purification, and the third filter residue is a calcium silicate and magnesium silicate precipitate, which can be used as a roadbed paving material;

[0087] After deep purification, the NaCl solution is sent to the chlor-alkali process as dissolved brine. The main reactions are:

[0088]

[0089] In Example 4, it was found through testing that the present method was used to solidify calcium and magnesium impurities in titanium metallurgical molten salt slag, and the recovery rate of NaCl in the waste salt slag reached 82.5%.

[0090] In summary, the method of solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using sodium sulfate or sodium silicate can solidify calcium and magnesium impurities in titanium metallurgical molten salt slag, and the NaCl recovery rate in the waste salt slag can reach more than 80%; the obtained calcium and magnesium waste slag is used as roadbed paving material, which improves resource utilization and reduces environmental pollution.

[0091] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0092] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent, characterized in that: The specific steps are as follows: Step 1: After the waste salt slag from the molten salt chlorination furnace is discharged from the furnace, it is kept at 420-700° C. and subjected to a first solid-liquid separation to obtain a first filter residue and a first filtrate; Step 2, the first filter residue is returned to the molten salt chlorination furnace to continue the reaction, and the first filtrate is sent to the preheated high-temperature reaction furnace; Step 3, first add a specific amount of curing agent into the high temperature reaction furnace, then heat the high temperature reaction furnace to 600-830° C. and keep it warm for 0.1-2 hours to obtain solution A; During the heating process, compressed air needs to be passed into the first filtrate; Step 4, heating the solution A to 835-1100° C. and keeping the temperature for 0.2-4 hours to obtain a solid-liquid mixture B; Step 5, subjecting the solid-liquid mixture B to a second solid-liquid separation to obtain a second filtrate and a second filter residue; Step 6: Send the second filtrate to a molten salt chlorination furnace to continue the reaction; at the same time, cool the second filter residue, and then carry out a third solid-liquid separation after water dissolution-hydrolysis-standing-clarification treatment to obtain a salt solution and a third filter residue, thereby completing the solidification of calcium and magnesium impurities in the titanium metallurgical molten salt slag.

2. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 1, the first solid-liquid separation adopts one of pressure filtration, vacuum filtration or centrifugal filtration, and the medium of the first solid-liquid separation adopts porous high-temperature ceramics with a mesh density of 10ppi-600ppi.

3. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 2, the preheating temperature of the high temperature reaction furnace is 420-700°C.

4. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 3, the curing agent is sodium sulfate or sodium silicate.

5. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 3, the specific amount of curing agent is calculated as follows: first, the salt solution in the molten salt chlorination furnace is sampled and analyzed, and then the specific amount of curing agent is calculated according to the Ca content in the sample. 2+ Mg 2+ The ion mass percentage X, Y, calculates the amount of curing agent added W in the high temperature conversion process, and the calculation formula is: Among them, 1.05 is the excess coefficient of the curing agent; 1000 is the calculation base for the mass of the salt slag to be converted, which is 1000kg; β is the molar mass of the curing agent, unit: g / mol; 40 is the molar mass of calcium ions, unit: g / mol; 24.3 is the molar mass of magnesium ions, unit: g / mol; X is the mass percentage of calcium ions in the salt slag to be converted; Y is the mass percentage of magnesium ions in the salt slag to be converted; M is the mass of the salt slag to be converted, unit: kg.

6. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 3, the heating rate of the first filtrate is 5-25°C / min.

7. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 3, the pressure of the compressed air is 0.01MPa-1.5MPa.

8. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 4, the heating rate of the solution A is 5-25°C / min.

9. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 5, the second solid-liquid separation adopts one of pressure filtration, vacuum filtration or centrifugal filtration, and the medium of the second solid-liquid separation adopts porous high-temperature ceramics with a mesh density of 10ppi-600ppi.

10. The method for solidifying calcium and magnesium impurities in titanium metallurgical molten salt slag using a solidifying agent according to claim 1, characterized in that: In step 6, a plate and frame filter press is used to perform a third solid-liquid separation.

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