Process method for reducing hardness of rare earth carbon precipitation wastewater in rare earth industry

Abstract

The invention discloses a process method for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry, and particularly relates to the technical field of rare earth hydrometallurgy wastewater treatment.The process method comprises the following steps that S1, high-hardness rare earth wastewater is introduced into an adjusting tank; s2, ammonia water is introduced into the adjusting tank, the high-hardness rare earth wastewater and the ammonia water are mixed, and the pH value of the mixed solution is adjusted to 9-10; s3, performing primary filtration on a mixed solution of the high-hardness wastewater and ammonia water; s4, pumping the filtrate of the high-hardness rare earth wastewater and ammonia water mixed solution into the micro-channel reactor by using a pump; s5, CO2 is introduced into the microchannel reactor containing the filtrate of the high-hardness rare earth wastewater and ammonia water mixed solution; s6, the high-hardness rare earth wastewater and ammoniacase-CO2 mixed solution enters a precision filtering device in a gravity flow mode, and solid precipitates and liquid in the mixed solution are separated; and S7, recycling the filtered and separated liquid clear liquid. 88-95% of calcium and magnesium ions in water can be removed, and the pH of the wastewater is adjusted to be neutral.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth hydrometallurgical wastewater treatment, in particular to a process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry. Background Art

[0002] The rare earth extraction transformation process will produce a large amount of wastewater with complex and diverse pollutants. Usually, lime is used to neutralize the acidic wastewater. Some process sections will choose to further evaporate and concentrate the wastewater to remove ammonium or obtain ammonium chloride products. These production processes will lead to an increase in the calcium and magnesium ion content and generate high-hardness wastewater. It is necessary to consider taking measures to reduce the calcium and magnesium ion content in the water.

[0003] The core of non-saponifiable or magnesium (calcium) oxide saponified extraction and separation technology is a non-saponifiable extraction method that pretreats the organic extractant with magnesium oxide, calcium oxide, etc., or replaces ammonia water or liquid alkali to saponify the organic extractant with calcium oxide or calcium hydroxide. This can fundamentally eliminate ammonia nitrogen wastewater pollution, but calcium and magnesium salt wastewater will be produced in the production process. It can be considered to adopt a process to recycle it to prepare high value-added products.

[0004] A large amount of calcium and magnesium ions causes the wastewater to be too hard, which can easily clog process pipelines or fail to meet discharge requirements or cause products to be high in impurities and impure.

[0005] Therefore, we made improvements and proposed a process method for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] The present invention discloses a process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry, comprising the following steps:

[0008] S1. Pass high-hardness rare earth wastewater into the regulating tank;

[0009] S2, passing ammonia water into the regulating tank to mix the high-hardness rare earth wastewater with ammonia water, and adjusting the pH value of the mixed solution to 9-10;

[0010] S3, the mixture of high hardness wastewater and ammonia water is subjected to primary filtration;

[0011] S4, using a pump to pass the filtrate of the mixture of high-hardness rare earth wastewater and ammonia water into the microchannel reactor;

[0012] S5, passing CO2 into a microchannel reactor containing a filtrate of a mixture of high-hardness rare earth wastewater and ammonia water;

[0013] S6, high-hardness rare earth wastewater and ammonia-CO2 mixed liquid enter the precision filtration device through gravity flow to separate the solid precipitate and liquid in the mixed liquid;

[0014] S7. Recycle the filtered and separated liquid clear liquid.

[0015] As a preferred technical solution of the present invention, the high-hardness rare earth wastewater in step S1 is high-calcium and high-magnesium wastewater after evaporation and concentration.

[0016] As a preferred technical solution of the present invention, in step S2, the ratio of ammonia water to calcium magnesium wastewater is wastewater: ammonia water = 5:1.

[0017] As a preferred technical solution of the present invention, the reactor used in S4 and S5 is a microchannel reactor.

[0018] As a preferred technical solution of the present invention, the precision filtering device used in S6 is an automatic backwashing surface filter.

[0019] As a preferred technical solution of the present invention, the S6 can perform solid-liquid separation on the mixed and stirred high-hardness rare earth wastewater, ammonia water and CO2 mixed liquid through the automatic backwashing surface filter to obtain rare earth carbon precipitation wastewater with lower hardness.

[0020] The beneficial effects of the present invention are:

[0021] 1. Utilize the waste gas generated in the rare earth production process - ammonia and carbon dioxide. Ammonia can be mixed with water to generate ammonia water, which is used in the entire process system. Carbon dioxide can be used to reduce hardness, achieving the purpose of treating waste with waste;

[0022] 2. After treatment, wastewater can be reused in the system, reducing water replenishment, saving resources and cost consumption;

[0023] 3. The waste residue after the reaction is dried to become a fine white powder containing calcium carbonate and magnesium carbonate, which can be further prepared into high value-added products as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 It is a process flow diagram of a process method for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry of the present invention;

[0026] Figure 2The present invention is a process device flow diagram of a process method for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] Example: Figure 1 and Figure 2 As shown, the present invention provides a process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry, comprising the following steps:

[0029] S1. Pass high-hardness rare earth wastewater into the regulating tank;

[0030] S2, passing ammonia water into the regulating tank to mix the high-hardness rare earth wastewater with ammonia water, and adjusting the pH value of the mixed solution to 9-10;

[0031] S3, the mixture of high hardness wastewater and ammonia water is subjected to primary filtration;

[0032] S4, using a pump to pass the filtrate of the mixture of high-hardness rare earth wastewater and ammonia water into the microchannel reactor;

[0033] S5, passing CO2 into a microchannel reactor containing a filtrate of a mixture of high-hardness rare earth wastewater and ammonia water;

[0034] S6, high-hardness rare earth wastewater and ammonia-CO2 mixed liquid enter the precision filtration device through gravity flow to separate the solid precipitate and liquid in the mixed liquid;

[0035] S7. Recycle the filtered and separated liquid clear liquid.

[0036] S1 medium-to-high hardness rare earth wastewater is high calcium and magnesium wastewater after evaporation and concentration.

[0037] The ratio of ammonia water to calcium magnesium wastewater in S2 is wastewater: ammonia water = 5:1.

[0038] The reactor used in S4 and S5 is a microchannel reactor. It should be noted that in the present application, the microchannel reactor is a Jinyu reactor, which is composed of a shell and a structural part, wherein the shell is made of metal, and the structural part includes a plurality of elastically deformable small-diameter hoses.

[0039] The precision filtration device used in S6 is an automatic backwashing surface filter.

[0040] In S6, the high-hardness rare earth wastewater, ammonia water and CO2 mixed liquid can be separated into solid and liquid through the automatic backwashing surface filter after mixing and stirring, so as to obtain rare earth carbon precipitation wastewater with lower hardness.

[0041] Example 1: A process method for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry, comprising the following steps: S1, passing calcium and magnesium wastewater into an equalization tank; S2, passing ammonia water into the equalization tank at a ratio of wastewater: ammonia water = 5:1, and adjusting the pH value of the wastewater in the equalization tank to 9; S3, filtering the mixed solution whose pH value is adjusted to 9, passing the filtered filtrate into a microchannel reactor, and passing CO2 gas into the microchannel reactor; S4, the mixed solution in the microchannel reactor flows to an automatic backwashing surface filter by gravity, and then the automatic backwashing surface filter is used to separate the mixed solution into solid and liquid; S5, collecting the produced calcium carbonate and magnesium carbonate precipitates to obtain softened rare earth carbon precipitation wastewater with relatively low hardness.

[0042] Example 2: A process method for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry, comprising the following steps: S1, passing calcium and magnesium wastewater into an equalization tank; S2, passing ammonia water into the equalization tank at a ratio of wastewater: ammonia water = 5:1, adjusting the pH value of the wastewater in the equalization tank to 10 and performing a primary filtration; S3, passing the filtrate after the primary filtration into a microchannel reactor, and passing CO2 gas into the microchannel reactor; S4, the mixed liquid in the microchannel reactor flows to an automatic backwashing surface filter by gravity, and then the mixed liquid is separated from the solid by the automatic backwashing surface filter; S5, collecting the produced calcium carbonate and magnesium carbonate precipitates to obtain softened rare earth carbon precipitation wastewater with relatively low hardness.

[0043] The following table shows the test data of a process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry in Example 1 and Example 2:

[0044] Table 7 Water hardness before and after treatment - List

[0045] Serial number Mother liquor water sample Sample No. Total hardness mg / L Decrease% Calcium hardness mg / L Decrease% 1 Concentrated wastewater after evaporation / 153000 / 15000 / 2 <![CDATA[Stock solution: NH4OH - CO2]]> 1# 17000 88.9 16000 893 3 The original wastewater before evaporation / 27000 / 20000 / 4 <![CDATA[Stock solution: NH4OH - CO2]]> 2# 3000 88.9 1000 95

[0046] Combining Example 1 and Example 2 and the above table, it can be seen that the method can remove 88-95% of calcium and magnesium ions in water, and after being treated by the method, the pH of the wastewater can be adjusted to neutral.

[0047] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or perform equivalent replacements on some of the technical features, such as the addition ratio of ammonia water, the pH of the mixed solution, etc. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry, characterized in that: The following steps are involved: S1. Pass high-hardness rare earth wastewater into the regulating tank; S2. Pass ammonia water into the regulating tank to mix the high-hardness rare earth wastewater with ammonia water, and adjust the pH value of the mixed solution to 9-10; S3, the mixture of high hardness wastewater and ammonia water is subjected to primary filtration; S4, using a pump to pass the filtrate of the mixture of high-hardness rare earth wastewater and ammonia water into the microchannel reactor; S5, passing CO2 into the microchannel reactor containing the filtrate of the mixture of high-hardness rare earth wastewater and ammonia water S6. The high-hardness rare earth wastewater and ammonia-CO2 mixed liquid enter the precision filtration device through gravity flow to separate the solid precipitate and liquid in the mixed liquid. S7. Recycle the filtered and separated liquid clear liquid.

2. A process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry according to claim 1, characterized in that: The high-hardness rare earth wastewater in step S1 is high-calcium and high-magnesium wastewater after evaporation and concentration.

3. A process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry according to claim 1, characterized in that: In step S2, the ratio of ammonia water to calcium magnesium wastewater is wastewater: ammonia water = 5:

1.

4. A process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry according to claim 1, characterized in that: The reactor used in S4 and S5 is a microchannel reactor.

5. A process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry according to claim 1, characterized in that: The precision filtering device used in S6 is an automatic backwashing surface filter.

6. A process for reducing the hardness of rare earth carbon precipitation wastewater in the rare earth industry according to claim 1, characterized in that: In S6, the high-hardness rare earth wastewater, ammonia water and CO2 mixed liquid after mixing and stirring can be separated into solid and liquid through the automatic backwashing surface filter to obtain rare earth carbon precipitation wastewater with lower hardness.

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