KR102093004B1 - Method for comprehensive recovery of magnesium-containing smelting wastewater - Google Patents

Abstract

The present invention discloses a method for comprehensive recovery of magnesium-containing smelting wastewater. The method comprises the steps of adjusting the pH of an acid smelting wastewater containing magnesium sulfate using an alkaline material to obtain a slurry containing magnesium hydroxide and calcium sulfate; And carbonation by passing carbon dioxide gas through the slurry, followed by solid-liquid separation to obtain a solid sludge and magnesium hydrogen carbonate solution, wherein the alkaline material is a calcium-containing alkaline material. This method converts and uses calcium ions into calcium sulfate and a small amount of calcium carbonate through a deterministic process such as neutralization precipitation and carbonation carbonate, so it significantly reduces the content of calcium sulfate in regenerated water, so it scales pipes, transfer pumps, storage tanks, etc. In addition to effectively solving the problem, magnesium ions in the magnesium-containing smelting wastewater can be converted into a magnesium hydrogen carbonate solution and used again for smelting separation, thereby realizing not only circulating use of raw materials in the production process but also zero discharge of wastewater. Therefore, the resource utilization rate of the overall technology line is high, and the economic effect and social benefit are excellent.

Description

Method for comprehensive recovery of magnesium-containing smelting wastewater

The present invention relates to the field of smelting separation, and specifically to a method for comprehensive recovery of smelting wastewater containing magnesium.

A large amount of waste water is generated during the wet smelting separation production process. For example, the mixed rare earth ore of BAOTOU mainly uses a neutralization purification-extraction conversion separation process of roasting sulfate-immersion-magnesium oxide. The wastewater produced in this process is mainly acidic wastewater containing magnesium sulfate generated during the extraction conversion process of rare sulfuric acid solution, and the main components of the wastewater are sulfuric acid, hydrochloric acid, Mg ion, Ca ion, Al ion, F ion and heavy metal ion (e.g. For example, Pb, Cd and As).

In the process of wastewater treatment in a wet smelting plant, the traditional chemical neutralization method for neutralizing a large amount of acidic wastewater is neutralized by adding lime or calcium carbide sludge, in which case a large amount of calcium sulfate, calcium fluoride, magnesium hydroxide, etc. After the precipitate is formed and clarified, it is discharged when the wastewater reaches the standard. Although it is mainly consumed in the treatment process, it is a neutralizing agent such as lime and calcium carbide sludge, but has a large amount of precipitation, complicated sediment, and poor working environment. Most importantly, the recycling of wastewater obtained after treatment is limited. Therefore, if the calcium, magnesium, and sulfate content in the wastewater that has undergone such process treatment is saturated and circulating is used, calcium sulfate scaling occurs in the equipment such as pipes, transfer pumps, and storage tanks as the temperature changes, which greatly affects continuous production. Crazy In addition, since the salt content in the wastewater treated by this process is very high, discharged directly to the outside increases the mineralization of the water quality of the river, causing serious pollution to the soil, surface water, and groundwater, causing further deterioration of the ecological environment. As the new environmental protection law was implemented, the final goal was to solve the high salt wastewater problem and realize zero discharge of wastewater.

In the research and application of the circulating recovery treatment of smelting wastewater, the active studies are the membrane separation method, evaporation crystallization method, stripping method and discontinuous chlorine treatment method. The membrane separation method is effective because it separates ions, molecules, or particulates in water by selectively using permeability, but it easily causes membrane contamination. The evaporation crystallization method reaches the purpose of evaporating and concentrating the salt-containing wastewater to reach a supersaturated state, and then gradually forming a crystalline solid after the salt forms crystal nuclei in the wastewater. The method is suitable for use in the treatment of high salt wastewater. The stripping method reaches the purpose of separating contaminants from wastewater by direct contact of wastewater and water vapor to allow volatile substances in the wastewater to diffuse into the gas phase at a constant rate. This method is mainly used to treat easily volatile contaminants. The break point chlorination method reaches the purpose of removing ammonia nitrogen by oxidizing ammonia nitrogen to N ₂ by adding a certain amount of chlorine gas or sodium hypochlorite to the wastewater. These methods have limitations for use in industry because of high defects and high investment costs.

Therefore, there is a need to provide a wastewater treatment process capable of recycling wastewater after treatment, which is low cost, environmentally friendly, and still improves the prior art in terms of comprehensive recovery of smelted wastewater.

The present invention mainly aims to provide a wastewater treatment process that is low in cost, environmentally friendly, and can recycle the wastewater after treatment by providing a method for comprehensively recovering magnesium-containing smelting wastewater.

In order to realize the above object, there is provided a method of comprehensively recovering smelting wastewater containing magnesium according to an aspect of the present invention. The method comprises the steps of obtaining a slurry containing magnesium hydroxide and calcium sulfate by adjusting the pH of the smelting wastewater containing magnesium as an neutralizing agent to between 10.0 and 12.5; And step S2 of passing a carbon dioxide gas through a slurry containing magnesium hydroxide and calcium sulfate to proceed with carbonation and performing solid-liquid separation on the carbonated slurry to obtain a solid sludge and magnesium hydrogen carbonate solution, wherein the step In S1, the magnesium-containing smelting wastewater is a magnesium sulfate-containing wastewater, and the alkaline substance is a calcium-containing alkaline substance.

Furthermore, the magnesium-containing smelting wastewater is a magnesium sulfate-containing wastewater generated through treatment of sulphated roasting, immersion, neutralization and purification of magnesium oxide, and extraction conversion in the smelting separation process.

Further, when the magnesium-containing smelting wastewater is magnesium sulfate-containing acidic wastewater, step S1 comprises: adjusting the pH value of the magnesium-containing smelting wastewater between 4.0 and 10.0 using a calcium-containing alkaline material to obtain a solid-liquid mixture; Filtering the solid-liquid mixture to obtain a filtrate S12; And a step S13 in which a pH value of the filtrate is adjusted between 10.0 and 12.5 using a calcium-containing alkaline material to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Further, step S1 includes adding calcium sulfate seed crystals to the magnesium-containing smelting wastewater; And / or subjecting the slurry containing magnesium hydroxide and calcium sulfate to an aging treatment.

Furthermore, in the step of aging the slurry containing magnesium hydroxide and calcium sulfate, the aging time is 0.5 h to 6 h.

Further, in step S2, carbonation is performed by passing carbon dioxide gas through the slurry, and a pH value of the slurry is controlled in the range of 6.5 to 8.0 in the course of carbonation to obtain a carbonated slurry; And performing solid-liquid separation on the carbonated slurry to obtain a solid sludge and magnesium hydrogen carbonate solution.

Furthermore, the calcium ion concentration in the magnesium hydrogen carbonate solution is 0.01 g / L-0.7 g / L and preferably 0.01 g / L-0.4 g / L.

Furthermore, the solid sludge is purified to obtain calcium sulfate, or smelting and separation is carried out to return to the acidic wastewater, which is then neutralized to prepare calcium sulfate.

Furthermore, carbon dioxide gas is produced by process waste gas, and the process waste gas is one or more species of gas generated by saponifying and extracting boiler combustion gas, oxalate precipitation and carbonate precipitation roasting urinary gas, and magnesium hydrogen carbonate solution.

Furthermore, in step S2, the magnesium hydrogen carbonate solution is used in the wet smelting process, and the smelting process is ore sulfuric acid roasting-immersion-neutralization purification process, pickling-neutralization purification process, solution extraction conversion or precipitation conversion process, solution extraction separation It is one or many species in the process and solution precipitation process.

In the application of the technical method of the present invention, the method adjusts the pH value between 10.0 and 12.5 by adding an alkaline substance to the magnesium-containing smelting wastewater, converts Mg ²⁺ in the wastewater to magnesium hydroxide, and simultaneously converts a large amount of Ca ²⁺ . Convert to calcium sulfate precipitation. Magnesium hydroxide is converted to soluble magnesium hydrogen carbonate after carbonation treatment, and a small amount of calcium ions is additionally removed in the form of calcium carbonate precipitation. When the wastewater was reused by lowering it, the scaling problem of pipes, transfer pumps, and storage tanks was effectively solved.

The drawings constituting a part of the present application are intended to further understand the present invention, and the schematic embodiments and descriptions of the present invention are intended to interpret the present invention and do not unduly limit the present invention. Looking at the attached drawings,
1 is a schematic diagram showing the flow of a method for comprehensive recovery of magnesium-containing smelting wastewater according to one preferred embodiment of the present invention.

What should be described herein, the embodiments of the present application and the configurations of the embodiments can be combined with each other in a situation where there is no collision. The present invention will be described in detail in conjunction with the examples below.

As mentioned in the prior art, the treatment method of the magnesium-containing smelting wastewater of the prior art is limited in the use of circulation because the cost of treatment is too high or the salt content of the wastewater after treatment is too high. In order to improve the above problems of the prior art, an exemplary embodiment of the present invention provides a method of comprehensively recovering and recycling magnesium-containing smelting wastewater as shown in FIG. 1. The method comprises the steps of obtaining a slurry containing magnesium hydroxide and calcium sulfate by adjusting the pH value of the magnesium-containing smelting wastewater between 10.0 and 12.5 using an alkaline material as a neutralizing agent; And step S2 of passing carbon dioxide gas through a slurry containing magnesium hydroxide and calcium sulfate to proceed with carbonation, and performing solid-liquid separation on the carbonated slurry to obtain a solid sludge and magnesium hydrogen carbonate solution.

In step S1, the magnesium-containing smelting wastewater is magnesium sulfate-containing wastewater and the alkaline substance is a calcium-containing alkaline substance.

In the above method, for the magnesium-containing smelting wastewater, the pH of the wastewater is adjusted to between 10.0 and 12.5 by using a calcium-containing alkaline substance (including calcium and magnesium-containing alkaline substances) as a neutralizing agent, and Mg ²⁺ in the magnesium-containing smelting wastewater. At the same time as converting to magnesium hydroxide, the added calcium-containing alkaline substance is removed after producing calcium sulfate precipitate under the action of H + and SO ₄ ^2-in the smelting wastewater. Then, carbon dioxide gas is passed through a slurry containing the magnesium hydroxide and calcium sulfate to convert the magnesium hydroxide in the wastewater to soluble magnesium hydrogen carbonate, and at the same time, a small amount of free Ca ²⁺ remaining in the wastewater is removed. By converting it to calcium carbonate and further separating it from magnesium ions, the calcium ions in the magnesium hydrogen carbonate solution obtained by recovery are thoroughly separated to significantly reduce the content of CaSO ₄ in the recovered circulating water, thereby preventing scaling problems such as pipes, transfer pumps, and storage tanks. In addition to effectively solving the problem, the obtained hydrogen hydrogen carbonate solution is used in the smelting separation process to realize circulating use of waste water as well as zero discharge of waste water.

The wastewater containing magnesium sulfate treated in the above method is magnesium sulfate produced through treatment of roasting sulfate, immersion, neutralization of magnesium oxide, and extraction conversion process during the smelting and separation process of ores such as monazite, genotime, bustnesite, and nickel cobalt ore. Contains waste water, but is not limited thereto. Any waste water containing magnesium sulfate produced in the process of separating any light can be recovered and used using the method of the present invention.

In the step S1, there are various methods of adjusting the pH of wastewater between 10.0 and 12.5 by adding an alkaline substance as a neutralizing agent, and specific control methods can be reasonably adjusted according to actual production demand. In one preferred embodiment of the present invention, when the magnesium-containing smelting wastewater is a magnesium sulfate-containing acidic wastewater, the step S1 is a solid-liquid mixture by adjusting the pH value of the magnesium-containing smelting wastewater between 4.0 and 10.0 using a calcium-containing alkaline substance. Obtaining step S11; Filtering the solid-liquid mixture to obtain a filtrate S12; And a step S13 in which a pH value of the filtrate is adjusted between 10.0 and 12.5 using a calcium-containing alkaline material to obtain a slurry containing the magnesium hydroxide and calcium sulfate.

In the above preferred embodiment, the main purpose of obtaining a solid-liquid mixture by adjusting the pH value of the magnesium-containing smelting wastewater between 4.0 and 10.0 using a calcium-containing alkaline substance is to neutralize H + in the smelting wastewater, and calcium sulfate in the treated circulating water. This is to reduce the problem of pipe scaling, which is easily seen when the recycled water is reused by reducing the content. Therefore, all of the calcium-containing alkaline substances capable of providing an alkaline environment and easily converting and removing calcium therein into calcium sulfate are applicable to the present invention. It is preferred to use calcium hydroxide. The source of calcium hydroxide is not limited to a solid powder of calcium hydroxide, and alkaline calcium hydroxide obtained by reacting calcium oxide obtained after roasting calcium oxide or calcium carbonate is also possible. Considering the cost of treatment of the smelting wastewater and the angle from which the raw material is recycled, it is preferable to prepare the calcium hydroxide-containing alkaline substance by using a limestone (or dolomite) or the like that is rich in nature and inexpensive.

Similarly, an alkaline substance containing calcium and magnesium refers to a mixture containing calcium hydroxide and magnesium hydroxide at the same time, and the mixture is a product of water after roasting minerals containing calcium and magnesium or industrial waste containing calcium and magnesium. It may be a mixture containing calcium hydroxide and magnesium hydroxide obtained by reacting with or a mixture containing calcium hydroxide and magnesium hydroxide obtained after digestion by a small dolomite.

In the preferred embodiment, when the pH value of the smelting wastewater is adjusted to between 4.0 and 10.0 by using the calcium-containing alkaline material, a large amount of H + in the smelting wastewater may be neutralized and calcium may be separated from the wastewater as calcium sulfate. After adjusting the pH value of the smelting wastewater using a calcium-containing alkaline substance to between 4.0 and 10.0 to obtain a solid-liquid mixture, filtering is performed on the solid-liquid mixture to remove precipitated calcium sulfate therefrom to obtain a filtrate. Subsequently, the pH value of the filtrate is adjusted to between 10.0 and 12.5 using an alkaline substance containing calcium and magnesium or an alkaline substance containing calcium. Mg2 + in the smelting wastewater is controlled by controlling the addition amount and pH value of the added calcium-containing alkaline substance neutralizing agent to precipitate calcium magnesium ions in the wastewater step by step and controlling the pH value of the filtrate after removing calcium sulfate to a range of 10.0 to 12.5. Calcium and / or magnesium are converted to magnesium hydroxide in alkaline conditions to obtain a slurry of precipitate containing magnesium hydroxide and calcium sulfate. Specifically, the following reaction occurs.

2H ⁺ (liquid) + SO4 ^2- (liquid) + Ca (OH) ₂ (high) → CaSO ₄ (high) + H ₂ O (liquid)

Mg ^{2 +} (liquid) + SO4 ^2- (liquid) + Ca (OH) ₂ (high) → Mg (OH) ₂ (high) + CaSO ₄ (high)

In the preferred embodiment, the purpose of precipitating calcium sulfate can be reached by simply adjusting the pH value of the magnesium-containing smelting wastewater between 4.0 and 10.0 using a calcium-containing alkaline material. In another preferred embodiment of the present invention, in order to cause precipitation to occur easily or to proceed thoroughly, in the step S1, adding calcium sulfate seed crystals to the magnesium-containing smelting wastewater; And / or aging the slurry containing magnesium hydroxide and magnesium sulfate. When calcium sulfate seed crystals are added, calcium sulfate precipitation easily occurs and the precipitation reaction proceeds relatively thoroughly. Likewise, the aging treatment allows the precipitation to be relatively thorough. The specific aging time can be appropriately adjusted according to the amount of smelting wastewater treated, and in one preferred embodiment of the present invention, the aging treatment time is equal to or less than 6 h. If the aging time is controlled within 6 h, the calcium sulfate precipitation proceeds thoroughly, which is advantageous for the recycling of wastewater after treatment. If the aging time is continuously extended, the operation of the overall process is delayed, which is disadvantageous for the process.

Smelting waste water recovered in the process of this invention is a waste water containing magnesium sulfate, the wastewater is mainly Mg ^2+, H ⁺ and SO4 ^2-, and including, Na ^+, Cl ^-, comprise one kind or multiple kinds of NO ^3- It is possible, the system is complex, and there are many kinds of ions to be caught. When treated with a calcium-containing alkaline material, calcium ions exist as precipitates of calcium sulfate in the system of sulfate ions, produce a solid mixture with magnesium hydroxide, and enter the carbonation step. In the course of carbonation, if a large amount of calcium ions are present in the system to induce hydrogen carbonate to form calcium carbonate crystals, the production rate of magnesium hydrogen carbonate is lowered and magnesium hydrogen carbonate is decomposed and precipitated as a magnesium carbonate solid, resulting in large scale scaling. It will have a great influence on the production of serialization.

Therefore, the present invention produces a low-activity stable crystal-type calcium sulfate precipitate by appropriately controlling the pH value during the alkali conversion process, thereby lowering the concentration of calcium ions in the aqueous phase after alkali conversion and low-activity calcium sulfate. Again, it is not easily dissolved as calcium ions, so it does not lower the carbonate rate. In the above-described preferred embodiment, stepwise control of the pH value to achieve stepwise alkali conversion of calcium ions and magnesium ions. Then, by first realizing the purpose of removing partial calcium through solid-liquid separation, the concentration of calcium ions in the water phase is lowered in the early stage of carbonate. When the calcium ions are alkali-converted and precipitated step by step by adding seed crystals and / or by proceeding with an aging treatment, the precipitation is more thorough and the concentration of calcium ions in the initial aqueous phase of the carbonate is further lowered, so that the carbonate effect is more excellent.

In the carbonation step, the purpose of the carbonation is to convert magnesium hydroxide in the slurry to soluble magnesium hydrogen carbonate, and at the same time, calcium ions remaining in the slurry are formed of calcium carbonate to be further removed. Therefore, the amount of carbon dioxide passed in the carbonation step can be reasonably adjusted according to the amount of wastewater to be treated. In one preferred embodiment of the present invention, the step S2 comprises: carbonizing gas by passing carbon dioxide gas through the slurry and controlling the pH value of the slurry in the carbonation process to a range of 6.5 to 8.0 to obtain a carbonated slurry; And performing solid-liquid separation on the carbonated slurry to obtain a solid sludge and magnesium hydrogen carbonate solution.

The wastewater that has undergone the neutralization precipitation treatment is a mixed slurry containing Mg (OH) ₂ and CaSO ₄ , and a small amount of advantageous Ca ²⁺ , OH ^- and SO4 ^2- is added due to the slightly soluble properties of CaSO ₄ . Includes. Since carbonation is carried out using CO ₂ gas, solid Mg (OH) ₂ is converted to Mg (HCO ₃ ) ₂ solution. The presence of large amounts of HCO _3- ions converts free Ca ²⁺ in the aqueous phase to CaCO ₃ precipitation. That is, the conversion of calcium to solidification is promoted again, and the purpose of further removing calcium from the water phase is reached. The specific reaction formula of the carbonation process is as follows.

Mg (OH) ₂ (high) + 2CO ₂ (group) → Mg (HCO ₃ ) ₂ (liquid)

_{^{Ca 2 + + 2HCO 3 - -}} → CaCO 3 ( high) + H ₂ O (liquid) + CO ₂ (group)

Here, the following side reaction may occur in the course of the carbonation reaction.

Mg (OH) ₂ (high) + CO ₂ (high) + H ₂ O → MgCO _{3 ·} 3H ₂ O (high)

In the preferred embodiment, the method of controlling the pH value of the slurry in the range of 6.5 to 8.0 controls the amount of carbon dioxide passing through to precipitate and remove calcium ions in the slurry in the form of calcium carbonate as possible to reach the separation purpose of calcium magnesium. The concentration of calcium ions in the obtained magnesium hydrogen carbonate solution is as low as possible. Using the carbonation step of the above embodiment, the calcium ion concentration in the magnesium hydrogen carbonate solution obtained through solid-liquid separation is 0.01 g / L-0.7 g / L, and preferably 0.01 g / L-0.4 g / L. The lower the concentration of calcium ions in the magnesium hydrogen carbonate solution, the easier it is to recycle the circulating water, so it does not easily cause the pipe to scale, thus realizing circulating use of the smelting wastewater.

In the preferred embodiment, the time for carbonation is reasonably adjustable depending on the value of the calcium ion concentration in the slurry containing magnesium hydroxide. In another preferred embodiment of the present invention, the carbonation time of the carbonation step is preferably 10 min to 120 min, and more preferably 20 min to 60 min. When the carbonate time is controlled from 10 min to 120 min, not only can calcium ions remaining in the slurry containing magnesium hydroxide be removed, but also the treatment time of the overall wastewater treatment process is too long, which affects the cycle operation cycle, resulting in treatment efficiency. Does not degrade it. If the carbonation time is too long, calcium ions precipitated with calcium carbonate have too much carbon dioxide to be converted to calcium hydrogen carbonate, which is difficult to remove and also has a long treatment cycle, which affects the treatment efficiency of the smelting wastewater of the company. If the carbonate time is 10 min, the calcium ion concentration in the circulating water after treatment is high because the calcium ion is not thoroughly precipitated, which is disadvantageous for the circulation of water after treatment. Controlling the carbonation time within 20 min to 60 min further reduces the concentration of calcium ions in the magnesium hydrogen carbonate solution after treatment, and the treatment time is relatively short, which is advantageous for high-efficiency recycling of corporate wastewater.

The method provided by the present invention showed reasonable use of energy in many respects, and step S2 is no exception. In another preferred embodiment of the present invention, as shown in FIG. 1, the solid sludge obtained in step S2 is purified to obtain calcium sulfate. A specific purification treatment method is a sulfuric acid oxidation method, as shown in FIG. 1. In actual application, the specific purification method can be selected according to the specific production conditions and equipment, and the calcium sulfate obtained by purification can be sold as a product, thereby realizing the maximization of value. In another specific embodiment, the solid sludge is smelted and separated to return to the generated wastewater to proceed with neutralization treatment.

In the step of carbonization by passing the carbon dioxide gas (as shown in FIG. 1), the passed carbon dioxide gas is produced by saponifying and extracting the boiler combustion gas, oxalate precipitation, and carbon dioxide precipitation urinary tract gas and magnesium hydrogen carbonate solution. It is one or a large number of species. As shown in FIG. 1, the present invention can preferably obtain a gas containing carbon dioxide after the gas produced in the above several processes is used as a raw material, and after compression, purification, or other treatment steps. Carbon dioxide is used to carbonate the solution containing magnesium hydroxide to reach the objective of obtaining a magnesium hydrogen carbonate solution, as well as the rational use of the gas in the process, enabling low carbon emissions and meeting environmental requirements.

In step S2 of the present invention, the magnesium hydrogen carbonate solution obtained by treating the magnesium-containing smelting wastewater can be reused as circulating water (as shown in FIG. 1). Therefore, the magnesium hydrogen carbonate solution provided in the above method of the present invention can be used both in the step of using water or the step of using a weakly alkaline solution in the separation and smelting process of all light. That is, the magnesium hydrogen carbonate solution obtained after treatment through the above method is an ore sulfate-immersion-neutralization purification process, a pickling-neutralization purification process, a solution extraction conversion or precipitation conversion process, a solution extraction separation process and / or a solution precipitation process. It can be used for one or many. For example, the BAOTOU rare earth concentrate sulfuric acid roasting immersion neutralization purification process, the BAOTOU ore rare earth conversion extraction process, Sichuan's Bastnaesite and ion type rare earth mineral acid neutralization purification process, and the rare earth extraction separation process and rare earth solution It can be used in the sedimentation process to use circulation.

The beneficial effects of the present invention are further described in conjunction with the specific examples below.

Example 1

BAOTOU rare earth concentrates are treated with magnesium sulfate-containing wastewater generated through the process of roasting sulphate-immersion-neutralization of magnesium oxide-extraction and extracting calcium hydroxide in the wastewater (where calcium hydroxide is obtained by reacting quicklime with water). After addition, the reaction was carried out so that the pH value of the wastewater reached 10.0 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbon dioxide (where carbon dioxide is obtained by treating the gas generated by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate to control the pH value of the carbonated slurry to 7.3. After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.7 g / L, and the process returns to the rare earth solution extraction and separation process of BAOTOU rare earth concentrate.

Example 2

A mixture of calcium sulfate and magnesium hydroxide in wastewater (obtained by reacting light dolomite with water) as a target for treatment of wastewater containing magnesium sulfate generated by the process of converting BAOTOU sulfate-immersion-neutralization-neutralization-purification-extraction conversion After adding), the reaction was performed so that the pH value of the wastewater reached 11.0 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

The pH value of the carbonated slurry is controlled to 7.3 by passing carbon dioxide (here, carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) through a slurry containing magnesium hydroxide and calcium sulfate. Solid-liquid separation of the slurry after carbonation yields a solid sludge and magnesium hydrogen carbonate solution.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.62 g / L, and the process returns to the rare earth solution extraction and separation process of BAOTOU rare earth concentrate.

Example 3

BAOTOU rare earth concentrates are treated with magnesium sulfate-containing wastewater generated through the process of roasting sulphate-immersion-neutralization of magnesium oxide-extraction and extracting calcium hydroxide in the wastewater (where calcium hydroxide is obtained by reacting quicklime with water). After the addition, the reaction was carried out so that the pH value of the wastewater reached 11.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate, and the alkalinity of the slurry was 0.24 mol / L.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate, and the pH value of the carbonated slurry is carbonated for 60 min. Control by 7.3. After the carbonation, the slurry was solid-liquid-separated to obtain a solid sludge and magnesium hydrogen carbonate solution, the concentration of magnesium hydrogen carbonate was 3.15 g / L (calculated as MgO), and the carbonation rate was 65.7%.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate used to prepare cement.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.56 g / L, and the process returns to the rare earth solution extraction and separation process of BAOTOU rare earth concentrate.

Example 4

BAOTOU rare earth concentrate concentrates magnesium sulfate and wastewater generated through the conversion process of sulphate-immersion-magnesium oxide neutralization-extraction, and is a mixture of calcium hydroxide and magnesium hydroxide in wastewater (obtained by reaction of light dolomite and water) And reacted to reach a pH value of 12.5.0 of the wastewater to obtain a slurry containing magnesium hydroxide and calcium sulfate, and the alkalinity of the slurry is 0.37 mol / L.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate, and the pH value of the slurry after carbonation is controlled to 7.3. . After the carbonation, the slurry was solid-liquid-separated to obtain a solid sludge and magnesium hydrogen carbonate solution, the concentration of magnesium hydrogen carbonate was 5.55 g / L (calculated as MgO), and the carbonation rate was 75.5%.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate used to prepare cement.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.45 g / L, and the process returns to the rare earth solution extraction and separation process of BAOTOU rare earth concentrate.

Example 5

BAOTOU rare earth concentrate is treated with acidic wastewater containing magnesium sulfate, which is produced through the conversion process of sulphate roasting-immersion-magnesium oxide neutralization-extraction, and calcium hydroxide in wastewater (where calcium hydroxide is obtained by reacting quicklime with water) And reacted to bring the pH value of the wastewater to 12.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate to control the pH value of the slurry after carbonation to 7.5. . After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate used to prepare cement.

As a result of the measurement, the concentration of calcium ions in the solution of magnesium hydrogen carbonate is 0.4 g / L, and it returns to the rare earth solution extraction separation process, rare earth solution extraction separation, and precipitation process of BAOTOU rare earth concentrate.

Example 6

BAOTOU rare earth concentrate is treated with acidic wastewater containing magnesium sulfate, which is produced through the conversion process of sulphate roasting-immersion-magnesium oxide neutralization-extraction, and calcium hydroxide in wastewater (where calcium hydroxide is obtained by reacting quicklime with water) And reacted to bring the pH value of the wastewater to 12.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate, and the pH value of the slurry after carbonation is carbonated for 120 min. Is controlled to 6.5. Solid-liquid separation is performed on the carbonated slurry to obtain a solid sludge and magnesium hydrogen carbonate solution.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate used to prepare cement.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.58 g / L, and it returns to the leaching neutralization purification of BAOTOU rare earth concentrate, rare earth solution extraction conversion process, and rare earth solution extraction separation process.

Example 7

The wastewater containing magnesium sulfate produced by extracting and separating a nickel cobalt sulfate solution is targeted for treatment, and calcium hydroxide (here, calcium hydroxide is obtained by reacting quicklime with water) is added to the wastewater to react, resulting in a pH value of 12.5. To obtain a slurry containing magnesium hydroxide and calcium sulfate.

The slurry containing magnesium hydroxide and calcium sulfate is passed through carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution), followed by carbonation for 40 min and pH of the slurry after carbonation. The value is controlled to 8.0. After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate used to prepare cement.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.38 g / L, and the process returns to the extraction and separation process of the nickel sulfate cobalt solution.

Example 8

The BAOTOU rare earth concentrate is treated with magnesium sulfate-containing wastewater generated through the process of roasting sulfate-immersion-neutralization of magnesium oxide-extraction, and reacting after adding calcium hydroxide to the wastewater so that the pH value of the wastewater reaches 12.5. A slurry containing magnesium hydroxide and calcium sulfate is obtained.

Carbon dioxide (where carbon dioxide is obtained by treating the gas generated by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate to control the pH value of the slurry after carbonation to 7.0. . After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

Purification of solid sludge using sulfuric acid oxidation method to produce cement yields calcium sulfate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.49 g / L, and the process returns to the rare earth solution precipitation conversion process, rare earth solution extraction separation, and solution precipitation process of BAOTOU rare earth concentrate.

Comparative Example 1

BAOTOU rare earth concentrates are treated with acidic wastewater containing magnesium sulfate, which is produced through the process of converting sulfuric acid to immersion-neutralization of magnesium oxide-extraction, and after adding calcium hydroxide to the wastewater, the reaction proceeds and the pH value of the wastewater reaches 9.5. Upon reaching, a slurry containing magnesium hydroxide and calcium sulfate is obtained.

Carbon dioxide (where carbon dioxide is obtained by treating the gas generated by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate to control the pH value of the slurry after carbonation to 7.3. . After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate used to prepare cement.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 1.0 g / L, and the process returns to the rare earth solution extraction conversion process and rare earth solution extraction separation process of BAOTOU rare earth concentrate.

Comparative Example 2

BAOTOU rare earth concentrates are treated with magnesium sulfate wastewater generated through the process of converting sulfuric acid to immersion-neutralization of magnesium oxide-extraction, and reacting after adding calcium hydroxide to the wastewater so that the pH value of the wastewater reaches 13.0. A slurry containing magnesium hydroxide and calcium sulfate is obtained.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate to control the pH value of the slurry after carbonation to 7.3. . After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

The solid sludge is purified using a sulfuric acid oxidation method to obtain calcium sulfate used to prepare cement.

As a result of the measurement, the concentration of calcium ions in the solution of magnesium hydrogen carbonate is 1.1 g / L, and the process returns to the rare earth solution extraction conversion process, rare earth solution extraction separation, process of BAOTOU rare earth concentrate.

Example 9

BAOTOU Rare earth concentrate concentrates magnesium sulfate-containing acidic wastewater generated through the process of roasting sulfuric acid, immersion, magnesium oxide neutralization, and extraction, and reacts after adding production ash to the wastewater to reach a pH value of 5.0. After the mixture was obtained, solid-liquid separation was performed to obtain a filtrate. The pH value of the filtrate is adjusted to 12.5 using quicklime to obtain a slurry containing magnesium hydroxide and calcium sulfate.

The pH value of the slurry after carbonation is controlled to 7.5 by passing carbon dioxide (here, carbon dioxide is obtained after treating the gas generated by saponifying and extracting a magnesium hydrogen carbonate solution) to a slurry containing magnesium hydroxide and calcium sulfate. After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.3 g / L and is used again in the pickling-neutralization purification process of BAOTOU rare earth concentrate and in the precipitation process of rare earth solution of BAOTOU rare earth concentrate.

Example 10

After the BAOTOU rare earth concentrate is treated with magnesium sulfate-containing acidic wastewater, which is produced through the conversion process of sulphate-immersion-magnesium oxide neutralization-extraction, after the raw lime is digested, the pH value of the wastewater is adjusted to 5.0 to obtain a solid-liquid mixture. After aging for 6 h, solid-liquid separation is performed to obtain a filtrate. After the quicklime is summoned, the pH value of the filtrate is adjusted to 12.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate to control the pH value of the slurry after carbonation to 7.5. . After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.22 g / L, and is used again in the pickling-neutralization purification process of the BAOTOU rare earth concentrate and the precipitation process of the rare earth solution of the BAOTOU rare earth concentrate.

Example 11

BAOTOU rare earth concentrates are treated with magnesium sulfate-containing acidic wastewater produced through the process of converting sulfuric acid to immersion-neutralization of magnesium oxide-extraction, and after digestion of quicklime, the pH value of the wastewater is adjusted to 5.0 to obtain a solid-liquid mixture. After aging for 2h, solid-liquid separation is performed to obtain a filtrate. After the quicklime is digested, the pH value of the filtrate is adjusted to 7.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate, and the pH value of the slurry after carbonation is controlled to 7.5. . After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.24 g / L and used again in the pickling-neutralizing and purification process of the BAOTOU rare earth concentrate and the rare earth solution precipitation process of the BAOTOU rare earth concentrate.

Example 12

BAOTOU Rare earth concentrates are treated with magnesium sulfate-containing acidic wastewater, which is produced through the conversion process of sulphate-immersion-magnesium oxide neutralization-extraction, and after the raw lime is digested, the pH value of the wastewater is adjusted to 0.5 to obtain a solid-liquid mixture and 0.5 After aging for h, solid-liquid separation is performed to obtain a filtrate. After digestion of quicklime, the pH value of the filtrate is adjusted to 12.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbon dioxide (where carbon dioxide is obtained by treating the gas produced by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through a slurry containing magnesium hydroxide and calcium sulfate, and the pH value of the slurry after carbonation is controlled to 7.5. . After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.27 g / L, and it is used again in the pickling-neutralization purification process of the BAOTOU rare earth concentrate and in the precipitation process of the rare earth solution of the BAOTOU rare earth concentrate.

Example 13

BAOTOU rare earth concentrate concentrates magnesium sulphate-containing acidic wastewater produced through the conversion process of sulphate-immersion-magnesium oxide-extraction conversion, and proceeds with the reaction after adding quicklime to the wastewater and making calcium sulfate seed crystals in the reaction process By adding it, the pH value is adjusted to 5.0 to obtain a solid-liquid mixture and solid-liquid separation to obtain a filtrate. After digestion of quicklime, the pH value of the filtrate is adjusted to 12.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbon dioxide (where carbon dioxide is obtained by treating the gas generated by saponifying and extracting a magnesium hydrogen carbonate solution) is passed through the slurry containing magnesium hydroxide and calcium sulfate, and the pH value of the slurry after carbonation is controlled to 7.5. do. After the carbonation, the slurry is solid-liquid separated to obtain a solid sludge and magnesium hydrogen carbonate solution.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.25 g / L and used again in the pickling-neutralization purification process of the BAOTOU rare earth concentrate and the precipitation process of the rare earth solution of the BAOTOU rare earth concentrate.

Example 14

BAOTOU rare earth concentrate is treated with acid sulfate wastewater containing magnesium sulfate, which is produced through conversion process of sulphate-immersion-magnesium oxide neutralization-extraction, and after the raw lime is digested, the pH value of the wastewater is adjusted to 4.0 to obtain a solid-liquid mixture and obtain a solid solution. Separate to obtain a filtrate. After digestion by light dolomite, the pH value of the filtrate is adjusted to 11.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

A slurry containing magnesium hydroxide and calcium sulfate is obtained, and carbon dioxide (which is obtained by saponifying and extracting the gas produced by saponifying the combustion gas of a boiler combustion gas, rare earth oxalate and carbonate, and a magnesium hydrogen carbonate solution) is passed through the slurry. The carbonation process was performed and the pH value was controlled to 7.5 to obtain a slurry after carbonation, and the slurry after carbonation contained calcium sulfate and calcium carbonate precipitates, and a magnesium hydrogen carbonate solution.

The carbonated slurry is subjected to solid-liquid separation to obtain a magnesium hydrogen carbonate solution, a solid sludge containing calcium sulfate and calcium carbonate precipitates.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.33 g / L, and this solution returns to the rare earth solution extraction and separation process of the monazite concentrate and the rare earth solution precipitation process.

Solid sludge returns to neutralization of acidic wastewater during rare earth smelting separation.

Example 15

The acid wastewater containing magnesium sulfate produced through the process of converting sulphate to sulphate-immersion-magnesium oxide neutralization-extraction conversion is targeted for treatment, and after the quicklime is digested, the pH value of the wastewater is adjusted to 6.0 to obtain a solid-liquid mixture. Obtained, and separated by solid-liquid to obtain a filtrate; After digestion, the pH value of the filtrate was adjusted to 11.5 using a small dolomite to obtain a slurry containing magnesium hydroxide and calcium sulfate.

A slurry containing magnesium hydroxide and calcium sulfate is obtained, and carbon dioxide (which is obtained by saponifying and extracting the gas produced by saponifying the combustion gas of a boiler combustion gas, rare earth oxalate and carbonate, and a magnesium hydrogen carbonate solution) is passed through the slurry. The carbonation process was performed and the pH value was controlled to 7.3 to obtain a slurry after carbonation, and the calcium sulfate and calcium carbonate precipitates, and a magnesium hydrogen carbonate solution were included in the slurry after carbonation.

The carbonated slurry is subjected to solid-liquid separation to obtain a magnesium hydrogen carbonate solution, a solid sludge containing calcium sulfate and calcium carbonate precipitates.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.3 g / L, and this solution returns to the rare earth solution extraction separation process and rare earth solution precipitation process of the Monaz stone concentrate.

Example 16

The magnesium sulfate-containing acidic wastewater produced by extracting and separating a rare sulfuric acid solution is treated and the pH value of the wastewater is adjusted to 9.0 after digestion of quicklime to obtain a solid-liquid mixture, and solid-liquid separation to obtain a filtrate; After digestion by light dolomite, the pH value of the filtrate is adjusted to 11.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate, and the alkalinity of the slurry is 0.67 mol / L.

A slurry containing magnesium hydroxide and calcium sulfate is obtained, and carbon dioxide (which is obtained by saponifying and extracting the gas produced by saponifying the combustion gas of a boiler combustion gas, rare earth oxalate and carbonate, and a magnesium hydrogen carbonate solution) is passed through the slurry. The carbonation process was performed and the pH value was controlled to 7.3 to obtain a slurry after carbonation, and the calcium sulfate and calcium carbonate precipitates, and a magnesium hydrogen carbonate solution were included in the slurry after carbonation. The magnesium hydrogen carbonate concentration is 12.2 g / L (calculated as MgO) and the carbonation rate is 91.5%.

The carbonated slurry is subjected to solid-liquid separation to obtain a magnesium hydrogen carbonate solution, calcium sulfate and a solid sludge containing calcium carbonate precipitate.

As a result of the measurement, the concentration of calcium ions in the solution of magnesium hydrogen carbonate is 0.18 g / L, and this solution returns to the rare sulfate solution extraction separation process and rare earth solution precipitation process.

Example 17

The acidic wastewater containing magnesium sulfate produced by extraction conversion and extraction separation of the sulfuric acid rare earth solution is subject to treatment, and the pH value of the wastewater is adjusted to 10.0 after digestion of quicklime to obtain a solid-liquid mixture, and solid-liquid separation to obtain a filtrate; The pH value of the filtrate was adjusted to 11.5 using light dolomite to obtain a slurry containing magnesium hydroxide and calcium sulfate.

A slurry containing magnesium hydroxide and calcium sulfate is obtained, and carbon dioxide (which is obtained by saponifying and extracting the gas produced by saponifying the combustion gas of a boiler combustion gas, rare earth oxalate and carbonate, and a magnesium hydrogen carbonate solution) is passed through the slurry. The carbonation process was performed and the pH value was controlled to 7.3 to obtain a slurry after carbonation, and the calcium sulfate and calcium carbonate precipitates, and a magnesium hydrogen carbonate solution were included in the slurry after carbonation.

The carbonated slurry is subjected to solid-liquid separation to obtain a magnesium hydrogen carbonate solution, calcium sulfate and a solid sludge containing calcium carbonate precipitate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.08 g / L, and this solution is used to return to the circulation of the smelting and separation process of the rare sulfuric acid solution.

Example 18

The acidic wastewater containing magnesium sulfate produced by extracting and separating a rare sulfuric acid solution is treated and the pH value of the wastewater is adjusted to 4.0 after digestion of quicklime to obtain a solid-liquid mixture, and solid-liquid separation to obtain a filtrate; After digestion, the pH value of the filtrate is adjusted to 10.0 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

A slurry containing magnesium hydroxide and calcium sulfate is obtained, and carbon dioxide treatment is performed by passing carbon dioxide (a gas obtained by saponifying and extracting the urinary tract gas of rare earth oxalate and carbonate and a magnesium hydrogen carbonate solution) Proceed and control the pH value to 7.5 to obtain a slurry after carbonation, and the calcium sulfate contains calcium sulfate and calcium carbonate precipitates, and a magnesium hydrogen carbonate solution.

The carbonated slurry is subjected to solid-liquid separation to obtain a solution of magnesium hydrogen carbonate, a solid sludge containing calcium sulfate and calcium carbonate precipitate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.65 g / L, and this solution is used to return to the circulation of the smelting and separation process of the rare sulfuric acid solution.

Example 19

The magnesium sulfate-containing acidic wastewater produced by the rare sulfuric acid solution through an extraction separation process is treated and the pH value of the wastewater is adjusted to 4.0 after digestion of quicklime to obtain a solid-liquid mixture and solid-liquid separation to obtain a filtrate; After digestion, the pH value of the filtrate is adjusted to 11.0 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

A slurry containing magnesium hydroxide and calcium sulfate is obtained and carbon dioxide (obtained by saponifying extraction of boiler combustion gas, rare earth oxalate and carbonate roasting urinary gas, and magnesium hydrogen carbonate solution) is passed through a total recovery of the resulting gas. The carbonation treatment is performed and the pH value is controlled to 7.5 to obtain a slurry after carbonation, and a solution of calcium sulfate and calcium carbonate precipitates and magnesium hydrogen carbonate is included in the slurry after carbonation.

The carbonated slurry is subjected to solid-liquid separation to obtain a solution of magnesium hydrogen carbonate, a solid sludge containing calcium sulfate and calcium carbonate precipitate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.58 g / L, and this solution is used by returning to the circulation of the smelting separation process of the rare sulfuric acid solution.

Example 20

The magnesium cobalt sulfate solution is treated with magnesium sulfate-containing acidic wastewater produced through an extraction separation process, and after the quicklime is digested, the pH value of the wastewater is adjusted to 4.0 to obtain a solid-liquid mixture, and solid-liquid separation to obtain a filtrate; After digestion, the pH value of the filtrate was adjusted to 12.0 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

A slurry containing magnesium hydroxide and calcium sulfate is obtained, and carbon dioxide (which is obtained by saponifying and extracting the gas produced by saponifying the combustion gas of a boiler combustion gas, rare earth oxalate and carbonate, and a magnesium hydrogen carbonate solution) is passed through the slurry. The carbonation process was performed and the pH value was controlled to 7.5 to obtain a slurry after carbonation, and the slurry after carbonation contained calcium sulfate and calcium carbonate precipitates, and a magnesium hydrogen carbonate solution.

The carbonated slurry is subjected to solid-liquid separation to obtain a solution of magnesium hydrogen carbonate, a solid sludge containing calcium sulfate and calcium carbonate precipitate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.4 g / L, and this solution is used by returning to the circulation of the extraction and separation process of the nickel cobalt sulfate solution.

Example 21

The mixed concentrate of Monaz Stone and Genotime is treated with the acidic wastewater containing magnesium sulfate generated through the process of roasting sulfuric acid-immersion-neutralizing magnesium oxide-extracting, and adjusting the pH value of wastewater after digestion of quicklime to 10.0. Thus, a solid-liquid mixture was obtained, and solid-liquid separation was performed to obtain a filtrate; After the light dolomite is digested, the pH value of the filtrate is adjusted to 12.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

A slurry containing magnesium hydroxide and calcium sulfate is obtained and carbon dioxide (obtained by saponifying extraction of boiler combustion gas, rare earth oxalate and carbonate roasting urinary gas, and magnesium hydrogen carbonate solution) is passed through a total recovery of the resulting gas. The carbonation treatment was performed and the pH value was controlled to 6.5 to obtain a slurry after carbonation, and the slurry after carbonation contained calcium sulfate and calcium carbonate precipitates, and a solution of magnesium hydrogen carbonate.

The carbonated slurry is subjected to solid-liquid separation to obtain a magnesium hydrogen carbonate solution, a solid sludge containing calcium sulfate and calcium carbonate precipitates.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.5 g / L, and this solution is used after returning to the circulation of the rare earth smelting separation process of the mixed concentrate of monaz stone and genotime.

Example 22

The mixed concentrate of Genotime is treated with magnesium sulfate-containing acidic wastewater generated through a process of converting sulfuric acid to immersion-neutralization of magnesium oxide-extraction, and after the raw lime is digested, the pH value of the wastewater is adjusted to 3.5, and a small amount To obtain a solid-liquid mixture of, solid-liquid separation to obtain a filtrate; After digestion by light dolomite, the pH value of the filtrate is adjusted to 11.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbonation treatment by passing carbon dioxide (a gas obtained by saponifying and extracting the gas generated by saponifying and extracting a solution of boiler combustion gas, rare earth oxalate and carbonate, and a magnesium hydrogen carbonate solution) into a slurry containing magnesium hydroxide and calcium sulfate. Proceed to and control the pH value to 8.0 to obtain a slurry after carbonation, and a solution of calcium sulfate and calcium carbonate precipitates and magnesium hydrogen carbonate is included in the slurry after carbonation.

The carbonated slurry is subjected to solid-liquid separation to obtain a solution of magnesium hydrogen carbonate, a solid sludge containing calcium sulfate and calcium carbonate precipitate.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.36 g / L, and this solution is used after returning to the circulation of the mixed concentrate rare earth separation process of Genotime.

Comparative Example 3

The mixed concentrate of Genotime is treated with the acidic wastewater containing magnesium sulfate, which is produced through the process of converting sulfuric acid to immersion-neutralization of magnesium oxide-extraction, and proceeds to the reaction by adding quicklime to the wastewater and adjust the pH value to 11.0. To obtain a large amount of solid-liquid mixture, most of the magnesium is precipitated, and the solid-liquid is separated to obtain a filtrate. After digestion by a small dolomite, the pH value of the filtrate is adjusted to 12.5 to obtain a slurry containing magnesium hydroxide and calcium sulfate.

Carbonation treatment by passing carbon dioxide (a gas obtained by saponifying and extracting the gas generated by saponifying and extracting a solution of boiler combustion gas, rare earth oxalate and carbonate, and a magnesium hydrogen carbonate solution) into a slurry containing magnesium hydroxide and calcium sulfate. Proceed to and control the pH value to 8.0 to obtain a slurry after carbonation, and a solution of calcium sulfate and calcium carbonate precipitates and magnesium hydrogen carbonate is included in the slurry after carbonation. As a result of the measurement, the concentration of magnesium hydrogen carbonate was 0.54 g / L.

The carbonated slurry is subjected to solid-liquid separation to obtain a magnesium hydrogen carbonate solution, a solid sludge containing calcium sulfate and calcium carbonate precipitates.

As a result of the measurement, the calcium ion concentration in the solution of magnesium hydrogen carbonate is 0.14 g / L, and this solution is used by returning to the circulation of the rare earth separation process of the mixed concentrate of Genotime.

Comparative Example 4

BAOTOU rare earth concentrates are treated with magnesium sulfate-containing wastewater produced through a conversion process of sulphate-immersion-magnesium oxide neutralization-extraction, and react with magnesium-containing wastewater by taking quicklime to adjust the pH value of wastewater from 6.0 to 9.0 It is controlled and separated by solid-liquid to obtain filtrate and debris, and the calcium ion concentration in the filtrate is 1.1 g / L. When the filtrate is circulated, as the temperature changes, scaling such as calcium sulfate is easily formed in the pipe, transfer pump, or storage tank, so it has a serious effect on the circulating use of wastewater and has a great influence on continuous production.

As can be seen from the above description, the embodiment of the present invention has the following technical effects.

(1) Neutralization Precipitation and Carbonation Purification Through two decisive steps, calcium is converted from Mg ²⁺ in the unsaponifiable acidic wastewater of the sulfuric acid system to a solution of magnesium hydrogen carbonate and Ca ²⁺ in the wastewater to calcium sulfate and a small amount of calcium carbonate. Magnesium ions were thoroughly separated to significantly reduce the CaSO ₄ content in regenerated water, effectively solving scaling problems such as pipes, transfer pumps, and storage tanks.

 (2) Magnesium bicarbonate solution prepared by carbonation can be used in processes such as immersion, neutralization purification, saponification and extraction separation, and can be recycled to waste water to close to zero discharge, saving a large amount of water resources.

 (3) Calcium sulfate produced as a by-product in the first half has stable properties, does not affect the environment, and reaches the specifications of commercially available gypsum through further purification studies.

For example, the present invention can prepare a magnesium hydrogen carbonate solution immediately after the precipitation conversion and carbonate purification steps for the magnesium-containing smelting wastewater, and goes back to the rare earth smelting separation process. In this way, in addition to realizing the comprehensive circulation of wastewater in the rare earth smelting process, realization of the generated wastewater is high, and the resource utilization rate of the overall technology line is high, and the economic effect and social benefit are very remarkable.

In the acidic wastewater containing magnesium and calcium discharged by rare earth companies, the alkali conversion carbonation method of the present invention is used for comprehensive recovery to reduce pollution emission costs, as well as to clean and purify the purified magnesium hydrogen carbonate solution obtained by neutralizing the rare earth solution. , It is used to return to the process such as producing rare carbonic acid by separating the rare earth and sedimentation and extracting the saponified organic phase, thereby realizing the use of waste water circulation and zero discharge of the produced wastewater.

The above is only a preferred embodiment of the present invention, and the present invention is not limited to this, and for those skilled in the art, the present invention may have various modifications and changes and any proceeding within the spirit and principles of the present invention Modifications, equivalent replacements, improvements and the like are all within the protection scope of the present invention.

Claims (11)

In the method for recovering magnesium-containing smelting wastewater,
Including the step S1 to obtain a slurry containing magnesium hydroxide and calcium sulfate by adjusting the pH of the magnesium-containing smelting wastewater between 10.0 and 12.5 using an alkaline material;
Among them, the magnesium-containing smelting wastewater is magnesium sulfate-containing wastewater, and the alkaline substance is a calcium-containing alkaline substance,
The step S1 is
Step S11 to obtain a solid-liquid mixture by adjusting the pH value of the magnesium-containing smelting wastewater between 4.0 and 10.0 using the calcium-containing alkaline material;
Filtering the solid-liquid mixture to obtain a filtrate S12; And
Including the step S13; to obtain a slurry containing the magnesium hydroxide and calcium sulfate by adjusting the pH value of the filtrate between 10.0 and 12.5 using the calcium-containing alkaline material;
Magnesium containing step S2 comprising passing carbon dioxide gas through the slurry containing magnesium hydroxide and calcium sulfate to proceed with a carbonation reaction and performing solid-liquid separation on the carbonated slurry to obtain a solid sludge and magnesium hydrogen carbonate solution How to recover smelting wastewater. According to claim 1,
The magnesium-containing smelting wastewater is a method for recovering magnesium-containing smelting wastewater, which is magnesium sulfate-containing wastewater generated after treatment with sulphated roasting, immersion, neutralization of magnesium oxide, and extraction conversion in the smelting separation process. delete According to claim 1,
The step S1 is a step of adding calcium sulfate seed crystals to the magnesium-containing smelting wastewater, or performing an aging treatment on a slurry containing magnesium hydroxide and calcium sulfate, or calcium sulfate seed crystals to the magnesium-containing smelting wastewater. A method of recovering a magnesium-containing smelting wastewater further comprising the step of adding an aging treatment to the slurry containing magnesium hydroxide and calcium sulfate. The method of claim 4,
In the step of aging the slurry containing the magnesium hydroxide and calcium sulfate, the aging time is 0.5 h ~ 6 h, a method for recovering magnesium-containing smelting wastewater. According to claim 1,
In step S2,
Obtaining carbonate carbonate slurry by passing carbon dioxide gas through the slurry containing magnesium hydroxide and calcium sulfate and controlling the pH value of the slurry to a range of 6.5 to 8.0 during the carbonation process; And
Comprising the step of solid-liquid separation for the carbonated slurry to obtain the solid sludge and the magnesium hydrogen carbonate solution,
Method for recovering magnesium-containing smelting wastewater. The method of claim 1 or 6,
Method for recovering magnesium-containing smelting wastewater having a calcium ion concentration of 0.01 g / L-0.7 g / L in the magnesium hydrogen carbonate solution. The method of claim 1 or 6,
The method for recovering the magnesium-containing smelting wastewater for producing calcium sulfate by performing the neutralization treatment by returning the solid sludge to an acidic wastewater produced by smelting separation or through the oxidation treatment. According to claim 1,
The carbon dioxide gas is produced by a process waste gas, and the process waste gas is a combustion gas of boiler, oxalate precipitation, and carbonate precipitation, and one or more types of smelting containing magnesium, which is produced by saponifying and extracting a gas and a magnesium hydrogen carbonate solution. How to recover waste water. According to claim 1,
In step S2, the magnesium hydrogen carbonate solution is used in a wet smelting process, and the smelting process is ore sulfuric acid roasting-immersion-neutralization purification process, pickling-neutralization purification process, solution extraction conversion or precipitation conversion process, solution extraction separation process And a method of recovering magnesium-containing smelting wastewater, which is one kind of solution precipitation process. The method of claim 7,
Method for recovering magnesium-containing smelting wastewater having a calcium ion concentration of 0.01 g / L-0.4 g / L in the magnesium hydrogen carbonate solution.

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