Ionic rare earth mine leaching, extraction and leaching integrated green low-carbon mining method

Abstract

The invention provides a leaching, extraction and leaching integrated green low-carbon mining method for an ionic rare earth mine, and relates to the field of mineral mining. The method comprises the following steps: mixing treated raffinate with an ore leaching agent, injecting the mixture into an ore leaching stope through a liquid injection hole for ore leaching in an ore leaching field, carrying out an ore leaching reaction in an acid environment to obtain a mother solution, and removing mud from the mother solution to obtain a first supernatant; tail water obtained by leaching in the leaching period stope is injected into the tail liquid period stope through the liquid injection hole, tail liquid is collected, and second supernate is obtained after the tail liquid is subjected to silt removal; concentrating the second supernate to obtain a concentrated solution and produced water, and enabling the produced water to enter a leacheate pool to be used as leaching water; mixing the first supernatant and the concentrated solution to obtain a mixed solution, and performing extraction and reverse extraction on the mixed solution to obtain rare earth feed liquid and raffinate; the leaching is two-step leaching, the first-step leaching is leaching by using the produced water, the second-step leaching is alkali leaching, and the tail water is collected. The method is short in time consumption, high in rare earth recovery rate and environment-friendly.

Description

Technical Field

[0001] The present application relates to the field of mineral mining, and in particular to a green and low-carbon mining method integrating leaching, extraction and leaching of ionic rare earth mines. Background Art

[0002] The only process allowed for ionic rare earth ores is the in-situ leaching process, which uses ammonium sulfate or magnesium sulfate as a leaching agent. The production process of the leaching field is that the leaching agent is used to prepare the leaching solution, which is injected into the leaching field through the injection hole, and the mother liquor is collected through the liquid collection system; the general production process of the hydrometallurgical workshop is that the mother liquor enters the impurity removal tank, adds ammonium bicarbonate or sodium bicarbonate, and precipitates to obtain impurity-removed slag and impurity-removed liquid, and the impurity-removed liquid is added with ammonium bicarbonate or sodium bicarbonate and stirred and precipitated to obtain rare earth products and supernatant, and the supernatant enters the liquid preparation tank. The existing rare earth mine production process leaching field mainly considers leaching and liquid collection, and the hydrometallurgical workshop mainly considers mother liquor impurity removal and precipitation to obtain rare earth products. The mine production process is a leaching-hydrometallurgical process of "leaching solution-mother liquor collection-mother liquor impurity removal-rare earth precipitation-supernatant preparation of leaching solution", and the product is rare earth carbonate. The mother liquor is purified and precipitated with carbonate to adjust the mother liquor pH from about 4.0 to about 7.0, and acid neutralization produces carbon emissions; the carbonate rare earth products produce a large amount of carbon emissions in the subsequent acid dissolution process of separation and smelting. When the supernatant is prepared for leaching, sulfuric acid needs to be added to adjust the supernatant pH from about 7.0 to about 4.8, consuming a large amount of acid. In the in-situ leaching process, when the rare earth content in the collected mother liquor is less than 100 mg / L, the mine generally stops collecting the mother liquor, and the low-concentration rare earth leaching mother liquor is not recovered, resulting in a low rare earth recovery rate in the mine.

[0003] The in-situ leaching process of ammonium salt of ionic rare earth ore requires the addition of 6-12 tons of ammonium sulfate for every ton of rare earth produced, resulting in a large amount of ammonium sulfate accumulated in the leaching field; the in-situ leaching process of magnesium ammonium salt requires the addition of 8-15 tons of magnesium sulfate for every ton of rare earth produced, resulting in a large amount of magnesium sulfate accumulated in the leaching field. After the leaching is completed, a large amount of ammonium sulfate or magnesium sulfate is accumulated in the in-situ leaching field. Forced leaching is an effective environmental protection measure to reduce the residual leaching agent, but due to the large fluctuations in the water quality of the leaching tail water and the Al 3+ 、Re 3+ 、SO4 2- The high ion concentration easily forms membrane scaling, which affects the membrane life and is very costly. The tail water of leaching has the characteristics of complex water quality and large fluctuations in water quality, which makes the treatment of tail water of leaching difficult. Due to the complex and volatile water quality of tail water of leaching, the use of chemical, biological and membrane treatment methods has problems such as high cost and difficulty in stable operation. Leaching and tail water treatment as environmental protection measures are difficult to promote in mines, and the risk of pollution of water and soil environment by residual leaching agents in the leaching field is difficult to solve. Summary of the invention

[0004] The purpose of this application is to provide a green and low-carbon mining method integrating leaching and extraction of ionic rare earth mines to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] The present application provides a green and low-carbon mining method for ionic rare earth mines by leaching, extraction and leaching, comprising:

[0007] The treated liquid of the raffinate is mixed with the leaching agent and then injected into the mother liquor phase stope through the injection hole for leaching in the leaching field, and the mother liquor is obtained after leaching reaction in an acidic environment. The mother liquor enters the desludging tank, and the first mud cake and the first supernatant are obtained after desludging;

[0008] The tail water obtained by eluting the elution period stope is injected into the tail liquid period stope through the injection hole, and the tail liquid is collected and enters the desludging tank. After desludging, a second mud cake and a second supernatant are obtained; the second supernatant is concentrated to obtain a concentrated liquid and produced water, and the produced water enters the elution liquid tank and is used as elution water;

[0009] The mixed liquid obtained by mixing the first supernatant and the concentrated liquid is extracted and stripped to obtain a rare earth feed liquid and the raffinate;

[0010] The elution is a two-step elution, wherein the first step of elution is elution using the produced water, and the second step of elution is alkaline elution, and the tail water is collected.

[0011] Optionally, the rare earth ion concentration of the produced water is not higher than 10 mg / L.

[0012] Optionally, the rare earth ion concentration in the tail water is not higher than 100 mg / L.

[0013] Optionally, the eluent in the alkaline elution process is a mixture of the produced water and an alkaline solution, the pH value of the eluent is 8.5-9.0, and the alkaline solution includes sodium hydroxide.

[0014] Optionally, the leaching agent comprises magnesium sulfate.

[0015] Optionally, the pH value of the acidic environment is 4.8-5.0.

[0016] Optionally, when the rare earth ion concentration in the mother liquor is lower than 100 mg / L, the liquid collection is stopped.

[0017] Optionally, the concentration is membrane concentration, and the membrane concentration includes reverse osmosis membrane concentration.

[0018] Optionally, the rare earth ion concentration in the concentrated solution after the membrane concentration is not less than 400 mg / L.

[0019] Optionally, the rare earth ion concentration in the mother liquor is not less than 200 mg / L.

[0020] Optionally, the rare earth ion concentration in the tail liquid is 100-200 mg / L.

[0021] Optionally, the rare earth ion concentration of the mixed solution is not less than 400 mg / L.

[0022] Optionally, the rare earth ion concentration of the tail water is no more than 100 mg / L.

[0023] Optionally, the turbidity of the first supernatant and the second supernatant is no higher than 1 NTU.

[0024] Optionally, the treated liquid is obtained by removing oil from the raffinate.

[0025] Optionally, the method further comprises mixing the first mud cake and the second mud cake and then adding lime for backfilling, and the amount of lime added is 10%-20% based on the total mass of the first mud cake and the second mud cake being 100%.

[0026] Compared with the prior art, the beneficial effects of this application include:

[0027] The green and low-carbon mining method of ionic rare earth mines provided by the present application is recovered through membrane concentration, and the mother liquor treatment eliminates the impurity removal and precipitation processes, which avoids the loss of rare earths caused by impurity removal and precipitation, and the recovery rate of rare earths in mines is increased by about 10% to 20%, which significantly improves the recovery rate of rare earths. In addition, the technology of the present application adds alkaline leaching, and the acid-base environment of the ore soil is restored to the level before leaching after leaching, reducing the risk of release and pollution of acid-soluble metal ions in the ore soil after closure. The technology of the present application adds alkaline leaching, and the acid-base environment of the ore soil is restored to the level before leaching after leaching, reducing the risk of release and pollution of acid-soluble metal ions in the ore soil after closure. In addition, carbonates are not used in leaching, extraction, and leaching, which avoids carbon emissions in the production process, reduces carbon emissions and emission intensity, and realizes low-carbonization of the production process. The integrated green and low-carbon mining process of mine leaching, extraction and leaching realizes the coordination of mine leaching, extraction and leaching, realizes the separation and recycling of rare earth in mother liquor and tailings, improves the rare earth recovery rate, solves the problem of leaching and leaching tail water treatment and utilization, does not produce impurities and slag, and reduces the risk of mine soil pollution after site closure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0029] Figure 1 A schematic flow chart of an integrated green and low-carbon mining method for ionic rare earth mine leaching and extraction provided in an embodiment. DETAILED DESCRIPTION

[0030] As used herein:

[0031] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0032] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0033] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0034] In these examples, parts and percentages are by mass unless otherwise indicated.

[0035] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0036] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0037] In order to better explain the technical solution provided by this application, an overall statement of the technical solution is first made before the embodiments.

[0038] The present application provides a green and low-carbon mining method for ionic rare earth mines by leaching, extraction and leaching, which comprises:

[0039] The treated liquid of the raffinate is mixed with the leaching agent and then injected into the mother liquor phase stope through the injection hole for leaching in the leaching field, and the mother liquor is obtained after leaching reaction in an acidic environment. The mother liquor enters the desludging tank, and the first mud cake and the first supernatant are obtained after desludging;

[0040] The tail water obtained by eluting the elution period stope is injected into the tail liquid period stope through the injection hole, and the tail liquid is collected and enters the desludging tank. After desludging, a second mud cake and a second supernatant are obtained; the second supernatant is concentrated to obtain a concentrated liquid and produced water, and the produced water enters the elution liquid tank and is used as elution water;

[0041] The mixed liquid obtained by mixing the first supernatant and the concentrated liquid is extracted and stripped to obtain a rare earth feed liquid and the raffinate;

[0042] Wherein, the elution is a two-step elution, wherein the first step of elution is elution using the produced water, the second step of elution is alkaline elution, and the tail water is collected.

[0043] The method provided in the present application has a short process, in which rare earths are recovered from the mother liquor by an extraction process, and the mine product is a rare earth feed liquid; the process for recovering rare earths from general mother liquor to rare earth feed liquid is "impurity removal-precipitation-acid dissolution-extraction", and the rare earth recovery process from mine mother liquor is "impurity removal-precipitation", and the product is rare earth carbonate or rare earth enriched material. Compared with the general process, the technology of the present application eliminates the impurity removal, precipitation and subsequent acid dissolution steps, shortening the production process.

[0044] In an optional embodiment, the rare earth ion concentration in the produced water is not higher than 10 mg / L. The produced water enters the eluent pool and is used as eluent water, which reduces the waste of resources in the production process. The produced water also contains rare earth ions, which can further mine more ionic rare earth ores.

[0045] Optionally, the rare earth ion concentration in the produced water can be 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L, or any value between 0-10 mg / L.

[0046] In an optional embodiment, the rare earth ion concentration in the tail water is not higher than 100 mg / L.

[0047] Optionally, the concentration of rare earth ions in the tail water can be 1 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L, 100 mg / L, or any value between 0-100 mg / L.

[0048] In an optional embodiment, the elution liquid in the alkaline elution process is a mixture of the produced water and an alkaline solution, the pH value of the elution liquid is 8.5-9.0, and the alkaline solution includes sodium hydroxide. The present application reduces the risk of release and pollution of acid-soluble metal ions in the mine soil after closure by adding alkaline elution to restore the acid-base environment of the mine soil to the level before leaching.

[0049] Optionally, the pH value of the eluent may be 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, or any value between 8.5 and 9.0.

[0050] In an alternative embodiment, the leaching agent comprises magnesium sulfate.

[0051] In an optional embodiment, the pH value of the acidic environment is 4.8-5.0.

[0052] Optionally, the pH value of the acidic environment may be 4.8, 4.85, 4.9, 4.95, 5, or any value between 4.8 and 5.0.

[0053] In an optional embodiment, when the rare earth ion concentration in the mother liquor is lower than 100 mg / L, the liquid collection is stopped.

[0054] Optionally, the rare earth ion concentration in the mother liquor when the liquid collection is stopped can be 1 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, 45 mg / L, 50 mg / L, 55 mg / L, 60 mg / L, 65 mg / L, 70 mg / L, 75 mg / L, 80 mg / L, 85 mg / L, 90 mg / L, 95 mg / L, 100 mg / L, or any value between 0-100 mg / L.

[0055] In an optional embodiment, the concentration is membrane concentration, and the membrane concentration includes reverse osmosis membrane concentration.

[0056] In an optional embodiment, the rare earth ion concentration in the concentrated solution after the membrane concentration is not less than 400 mg / L. According to the change law of rare earth concentration in the leachate, the present application divides the leaching field into a mother liquor period mining field and a tail liquid period mining field, and the collected leachate is divided into a mother liquor and a tail liquid. Different enrichment schemes are adopted, and the tail liquid is concentrated by membrane to obtain a concentrated solution and produced water. The concentrated solution is mixed with the first supernatant to obtain a mixed solution. The rare earth concentration of the mixed solution is more stable, and the extraction process is more stable and the cost is lower.

[0057] Optionally, the rare earth ion concentration in the concentrated solution after the membrane concentration can be 400 mg / L, 450 mg / L, 500 mg / L, 550 mg / L, 600 mg / L, 650 mg / L, 700 mg / L, 750 mg / L, 800 mg / L, 850 mg / L, 900 mg / L, 950 mg / L, 1000 mg / L, or any value not less than 400 mg / L.

[0058] In an optional embodiment, the rare earth ion concentration in the mother liquor is not less than 200 mg / L.

[0059] Optionally, the rare earth ion concentration in the mother liquor may be 200 mg / L, 250 mg / L, 300 mg / L, 350 mg / L, 400 mg / L, 450 mg / L, 500 mg / L, or any value not less than 200 mg / L.

[0060] In an optional embodiment, the rare earth ion concentration in the tail liquid is 100-200 mg / L.

[0061] Optionally, the rare earth ion concentration in the tail liquid can be 100 mg / L, 110 mg / L, 120 mg / L, 130 mg / L, 140 mg / L, 150 mg / L, 160 mg / L, 170 mg / L, 180 mg / L, 190 mg / L, 200 mg / L, or any value between 100-200 mg / L.

[0062] In an optional embodiment, the rare earth ion concentration of the mixed solution is not less than 400 mg / L.

[0063] Optionally, the rare earth ion concentration in the mixed solution can be 400 mg / L, 450 mg / L, 500 mg / L, 550 mg / L, 600 mg / L, 650 mg / L, 700 mg / L, 750 mg / L, 800 mg / L, 850 mg / L, 900 mg / L, 950 mg / L, 1000 mg / L, or any value not less than 400 mg / L.

[0064] In an optional embodiment, the rare earth ion concentration of the tail water is no more than 100 mg / L.

[0065] Optionally, the rare earth ion concentration in the tail water can be 1 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, 45 mg / L, 50 mg / L, or any value between 0-100 mg / L.

[0066] In an optional embodiment, the turbidity of the first supernatant and the second supernatant is no higher than 1 NTU.

[0067] Optionally, the turbidity of the first supernatant and the second supernatant may be 0.1NTU, 0.2NTU, 0.3NTU, 0.4NTU, 0.5NTU, 0.6NTU, 0.7NTU, 0.8NTU, 0.9NTU, 1NTU, or any value between 0-1NTU.

[0068] In an optional embodiment, the treated liquid is obtained by removing oil from the raffinate.

[0069] In an optional embodiment, the method further comprises mixing the first mud cake and the second mud cake and then adding lime for backfilling, and the amount of lime added is 10%-20% based on the total mass of the first mud cake and the second mud cake as 100%.

[0070] Optionally, based on the total mass of the first mud cake and the second mud cake as 100%, the amount of lime added can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or any value between 10% and 20%.

[0071] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0072] Example 1

[0073] A rare earth mine uses magnesium sulfate to leaching ore, and the mother liquor uses extraction technology to recover rare earths. The product is rare earth liquid. There is one stope during the leaching period, one stope during the tailings period, and one stope during the leaching period. The liquid collection system consists of a liquid collection tunnel, diversion holes, liquid collection trenches, and seepage recovery wells. The collection rate of mother liquor, tailings, and tail water is 80%. The leaching intensity and leaching intensity are 3000m 3 / d, mother liquor collection time is 90 days, tail liquid collection time is 90 days, tail water collection time is 90 days, mother liquor volume is about 270,000 m 3 , tail liquid volume is about 270,000 m 3 , tailwater volume is about 270,000 m 3 The average rare earth content of the mother liquor is about 450 mg / L, and the average rare earth content of the tail liquor is about 130 mg / L.

[0074] like Figure 1 As shown, this embodiment provides an integrated green and low-carbon mining method for ion-type rare earth mines, and the specific steps are as follows:

[0075] (1) Leaching and mother liquor desludging

[0076] The leaching solution prepared by mixing the raffinate with magnesium sulfate has a pH value of 4.8 and is injected into the mother liquor stope through the injection hole for leaching. The mother liquor is collected by the liquid collection system. The mother liquor enters the desludging tank and is desludified to obtain mud cake and the first supernatant. Among them, the average rare earth ion concentration of the mother liquor is 450 mg / L, and the turbidity of the first supernatant is 0.9 NTU.

[0077] (2) Tail liquid and tail liquid concentration

[0078] The tail water obtained by eluting the elution period mining area is injected into the tail liquid mining area through the injection hole, and the tail liquid is collected by the liquid collection system. The tail liquid enters the mud removal tank, and the second mud cake and the second supernatant are obtained after mud removal; the second supernatant is concentrated to obtain the concentrated liquid and produced water, and the produced water enters the elution liquid tank and is used as elution water. Among them, the average rare earth ion concentration in the tail water is 60mg / L, the rare earth ion concentration in the tail liquid is 130mg / L, the turbidity of the second supernatant is 0.9NTU, the rare earth ion concentration in the concentrated liquid is 600mg / L, and the concentration of rare earth elements in the produced water is 5mg / L.

[0079] (3) Mixed liquid extraction

[0080] The first supernatant and the concentrated liquid are mixed to obtain a mixed liquid, and the mixed liquid is subjected to centrifugal extraction and back extraction to obtain a rare earth feed liquid product and a raffinate, and the raffinate is treated in an oil removal system to obtain a treated liquid. The rare earth feed liquid product is extracted, which is equivalent to about 263t of REO.

[0081] (4) Utilization of leaching and tail water

[0082] The produced water is injected into the mining area through the injection hole during the leaching period for a first-step produced water leaching; the produced water is added with sodium hydroxide to prepare the leaching solution, and then a second-step alkaline leaching is carried out, wherein the pH value of the leaching solution is 8.5. The leaching is carried out until the pollutants in the tail water are lower than the limit requirements of the relevant wastewater discharge standards. The tail water is collected by the liquid collection system and used for top water leaching in the mine during the tail liquid period.

[0083] (5) Backfill and seal the site

[0084] The first mud cake and the second mud cake are mixed, and the total mass of the first mud cake and the second mud cake is 100%, and the amount of lime added is 15% to obtain a mixed filler, which is backfilled at the bottom of the injection hole to a backfill height of 30 cm, and then the injection hole construction waste soil is backfilled thereon to plant plants.

[0085] The mother liquor adopts extraction process to recover rare earths, the mining product is rare earth liquid, and the production process is short; the collection and utilization of tail liquid is increased, and the rare earth recovery rate is 90%.

[0086] Example 2

[0087] A rare earth mine uses magnesium sulfate leaching and extraction process to recover rare earths. The product is rare earth liquid. There is one stope in the leaching period, one stope in the tailings period, and one stope in the leaching period. The liquid collection system consists of a liquid collection tunnel, diversion holes, liquid collection trenches, and seepage recovery wells. The collection rate of mother liquor, tailings, and tail water is 80%. The leaching intensity and leaching intensity are 4000m 3 / d, mother liquor collection time is 90 days, tail liquid collection time is 90 days, tail water collection time is 90 days, mother liquor volume is about 360,000 m 3 , tail liquid volume is about 360,000 m 3 , tailwater volume is about 360,000 m 3 The average rare earth content in the mother liquor is about 400 mg / L, and the average rare earth content in the tail liquor is about 120 mg / L.

[0088] This embodiment provides a green and low-carbon mining method for ion-type rare earth mines by leaching, extraction and leaching. The specific steps are as follows:

[0089] (1) Leaching and mother liquor desludging

[0090] The leaching solution prepared by mixing the raffinate with magnesium sulfate has a pH value of 4.8 and is injected into the mother liquor stope through the injection hole for leaching. The mother liquor is collected by the liquid collection system. The mother liquor enters the desludging tank and is desludified to obtain mud cake and the first supernatant. Among them, the average rare earth ion concentration of the mother liquor is 400 mg / L, and the turbidity of the first supernatant is 0.95 NTU.

[0091] (2) Tail liquid and tail liquid concentration

[0092] The tail water obtained by eluting the elution period mining area is injected into the tail liquid mining area through the injection hole, and the tail liquid is collected by the liquid collection system. The tail liquid enters the mud removal tank, and the second mud cake and the second supernatant are obtained after mud removal; the second supernatant is concentrated to obtain the concentrated liquid and produced water, and the produced water enters the elution liquid tank and is used as elution water. Among them, the average rare earth ion concentration in the tail water is 80mg / L, the average rare earth ion concentration in the tail liquid is 120mg / L, the turbidity of the second supernatant is 0.95NTU, the average rare earth ion concentration in the concentrated liquid is 500mg / L, and the concentration of rare earth elements in the produced water is 5mg / L.

[0093] (3) Mixed liquid extraction

[0094] The first supernatant and the concentrated liquid are mixed to obtain a mixed liquid, and the mixed liquid is subjected to centrifugal extraction and back extraction to obtain a rare earth feed liquid product and a raffinate, and the raffinate is treated in an oil removal system to obtain a treated liquid. The rare earth feed liquid product is extracted, which is equivalent to about 235t of REO.

[0095] (4) Utilization of leaching and tail water

[0096] The produced water is injected into the mining area during the leaching period through the injection hole for a first-step produced water leaching; the produced water is added with sodium hydroxide to prepare the leaching solution, and then a second-step alkaline leaching is carried out, wherein the pH value of the leaching solution is 9.0, and the leaching is carried out until the pollutants in the tail water are lower than the limit requirements of the relevant wastewater discharge standards. The tail water is collected by the liquid collection system and used for top water leaching in the mine during the tail liquid period.

[0097] (5) Backfill and seal the site

[0098] The first mud cake and the second mud cake are mixed, and the total mass of the first mud cake and the second mud cake is 100%, and the amount of lime added is 15% to obtain a mixed filler, which is backfilled at the bottom of the injection hole to a backfill height of 30 cm, and then the injection hole construction waste soil is backfilled thereon to plant plants.

[0099] The mother liquor adopts extraction process to recover rare earths, the mining product is rare earth liquid, and the production process is short; the collection and utilization of tail liquid is increased, and the rare earth recovery rate is 90%.

[0100] Comparative Example 1

[0101] The mother liquor is precipitated with sodium bicarbonate, and the product is rare earth carbonate. The tail water of leaching is treated with calcium aluminate method. A rare earth mine adopts magnesium salt in-situ leaching mining, with one leaching stope and one leaching stope. The liquid collection system consists of liquid collection tunnels, diversion holes, liquid collection trenches, seepage recovery wells, etc. The recovery rate of leaching mother liquor and leaching tail water is 80%, and the leaching intensity and leaching intensity are 3000m 3 / d, mother liquor collection time is 150 days, leaching tail water collection time is 150 days, leaching time is 150 days, leaching liquid volume is about 450,000 m3, leaching water volume is about 450,000 m3, average rare earth content of leaching mother liquor is about 250 mg / L, aluminum is about 70 mg / L; rare earth content of leaching tail water is about 60 mg / L, average magnesium is about 350 mg / L, sulfate is about 1000 mg / L, sodium is about 300 mg / L, and aluminum is about 50 mg / L.

[0102] This comparative example provides a method for leaching ore from magnesium sulfate in an ionic rare earth mine, and the specific steps are as follows:

[0103] (1) Ore leaching liquid

[0104] The leaching solution is prepared by adding magnesium sulfate and sulfuric acid to the supernatant of the mother liquor precipitation. When the rare earth ion concentration in the mother liquor is lower than 100 mg / L, the liquid collection is stopped.

[0105] (2) Mother liquor impurity removal and precipitation

[0106] The mother liquor enters the impurity removal tank, sodium bicarbonate is added to adjust the pH to 5.4, and the impurity removal slag and impurity removal liquid are precipitated. The impurity removal liquid enters the rare earth precipitation tank, sodium bicarbonate is added to adjust the pH to 7.0, and the precipitation is filtered to obtain rare earth carbonate product and supernatant, producing about 105t of impurity removal slag and 156t of rare earth carbonate product REO.

[0107] (3) Treatment of elution and tail water

[0108] Clean water is used to wash the mining area after leaching, and the washing tail water is collected. The washing tail water is treated by the calcium sulfide method, and the treatment cost of the washing tail water is about 5 million yuan.

[0109] (4) Backfill and seal the site

[0110] The abandoned soil from the injection hole is backfilled into the injection hole and compacted to 50 cm from the hole mouth. Then the topsoil is backfilled into the injection hole and plants are planted.

[0111] This comparative example is magnesium sulfate leaching, the mother liquor is precipitated by sodium bicarbonate, washed with clean water, and the tail water of the washing is treated by the calcium sulfonate method, while Example 1 is an integrated process of leaching-extraction-rinsing, the tail water of the washing is used as the top water of the tail liquid period, the tail water of the washing is fully utilized, and no carbonate is used in production. Compared with Example 1, the process of this comparative example is more complicated, the amount of rare earth recovery is about 50t less, the treatment fee of the washing tail water is about 5 million more, the consumption of sodium bicarbonate is about 320t, and the estimated carbon emission is about 180t more; the rare earth and leaching agent in the washing tail water are not recycled; the amount of impurity removal slag is about 105t, and the amount of sludge generated by the calcium sulfonate method for treating the washing tail water is about 1,100t, which needs to be stored and disposed.

[0112] Comparative Example 2

[0113] A rare earth mine uses ammonium salt in-situ leaching for mining. The mother liquor is precipitated by ammonium bicarbonate and washed with clean water. The tail water is treated by biological methods. The mine has one leaching site and one washing site. The liquid collection system consists of a liquid collection tunnel, diversion holes, liquid collection trenches, and seepage recovery wells. The recovery rate of leaching mother liquor and washing tail water is 80%. The leaching intensity and washing intensity are 3000m 3 / d, mother liquor collection time is 150 days, leaching tail water collection time is 180 days, leaching time is 180 days, and the leaching liquid volume is about 450,000 m 3 , the amount of leaching water is about 540,000 m 3 The average rare earth content in the leaching mother liquor is about 300 mg / L, and the aluminum content is about 50 mg / L; the average rare earth content in the leaching tail water is about 50 mg / L, ammonia nitrogen content is about 300 mg / L, sulfate content is about 1200 mg / L, and aluminum content is about 40 mg / L.

[0114] This comparative example provides a method for leaching ore in ammonium sulfate in an ionic rare earth mine, and the specific steps are as follows:

[0115] (1) Ore leaching liquid

[0116] The leaching solution is prepared by adding ammonium sulfate and sulfuric acid to the supernatant of the mother liquor after impurity removal and precipitation. When the rare earth ion concentration in the mother liquor is lower than 100 mg / L, the mother liquor collection is stopped.

[0117] (2) Mother liquor impurity removal and precipitation

[0118] The mother liquor enters the impurity removal tank, and ammonium bicarbonate is added to adjust the pH to 5.4. The impurity removal slag and impurity removal liquid are precipitated. The impurity removal liquid enters the rare earth precipitation tank, and ammonium bicarbonate is added to adjust the pH to 7.0. The rare earth carbonate product is precipitated, producing about 75t of impurity removal slag, and obtaining about 185t of rare earth carbonate product REO, and about 300t of ammonium bicarbonate is added.

[0119] (3) Treatment of elution and tail water

[0120] After leaching, the mining site uses clean water for leaching and collects the leaching tail water. The ammonia nitrogen in the leaching tail water is treated by biological methods. The cost of treating the leaching tail water is about 4.5 million yuan.

[0121] (4) Backfill and seal the site

[0122] The abandoned soil from the injection hole is backfilled into the injection hole and compacted to 50 cm from the hole mouth. Then the topsoil is backfilled into the injection hole and plants are planted.

[0123] This comparative example is ammonium sulfate leaching, the mother liquor is treated with ammonium bicarbonate for impurity removal and precipitation, clean water leaching, and the leaching tail water is treated by biological method, while Example 1 is an integrated leaching-extraction-leaching process, the leaching tail water is all used for the top water of the tail liquid period, and no carbonate is used. Compared with Example 1, the process of this comparative example is more complicated, the rare earth recovery is about 21 tons less, the leaching tail water treatment fee is about 4.5 million more, the ammonium bicarbonate consumption is about 300 tons, and the estimated carbon emissions are about 170 tons more; the rare earth and leaching agent in the leaching tail water are not recycled; 75 tons of impurity removal slag needs to be stored and disposed; the leaching time is about 90 days.

[0124] Comparative Example 3

[0125] A rare earth mine uses magnesium sulfate to leaching ore, and the mother liquor uses extraction technology to recover rare earths. The product is rare earth liquid. There is one stope during the leaching period, one stope during the tailings period, and one stope during the leaching period. The liquid collection system consists of a liquid collection tunnel, diversion holes, liquid collection trenches, and seepage recovery wells. The collection rate of mother liquor, tailings, and tail water is 80%. The leaching intensity and leaching intensity are 3000m 3 / d, mother liquor collection time is 90 days, tail liquid collection time is 90 days, tail water collection time is 90 days, mother liquor volume is about 270,000 m 3 The tail liquid volume is about 270,000 m3, and the tail water volume is about 270,000 m 3 The average rare earth content of the mother liquor is about 450 mg / L, and the average rare earth content of the tail liquor is about 130 mg / L.

[0126] like Figure 1 As shown, this comparative example provides an integrated green and low-carbon mining method for leaching and extraction of ionic rare earth mines, and the specific steps are as follows:

[0127] (1) Leaching and mother liquor desludging

[0128] The leaching solution prepared by mixing the raffinate with magnesium sulfate has a pH value of 4.8 and is injected into the mother liquor stope through the injection hole for leaching. The mother liquor is collected by the liquid collection system. The mother liquor enters the desludging tank and is desludified to obtain mud cake and the first supernatant. Among them, the average rare earth ion concentration of the mother liquor is 450 mg / L, and the turbidity of the first supernatant is 0.9 NTU.

[0129] (2) Tail liquid and tail liquid concentration

[0130] The tail water obtained from the first step of the leaching period mining site is injected into the tail liquid mining site through the injection hole, and the tail liquid is collected by the liquid collection system. The tail liquid enters the mud removal tank, and the second mud cake and the second supernatant are obtained after mud removal; the second supernatant is concentrated to obtain the concentrated liquid and produced water, and the produced water enters the leaching liquid pool and is used as leaching water. Among them, the average rare earth ion concentration in the tail water is 80mg / L, the average rare earth ion concentration in the tail liquid is 130mg / L, the turbidity of the second supernatant is 0.9NTU, the rare earth ion concentration in the concentrated liquid is 600mg / L, and the concentration of rare earth elements in the produced water is 5mg / L.

[0131] (3) Mixed liquid extraction

[0132] The first supernatant and the concentrated solution are mixed to obtain a mixed solution, and the mixed solution is subjected to centrifugal extraction and back extraction to obtain a rare earth feed liquid product and a raffinate, and the raffinate is treated in an oil removal system to obtain a treated liquid. The rare earth feed liquid product is extracted, and the REO conversion is about 235.

[0133] (4) Utilization of leaching and tail water

[0134] The produced water is added with sodium hydroxide to prepare the leaching solution, and then alkaline leaching is carried out, wherein the pH value of the leaching solution is 8. The elution is carried out until the pollutants in the tail water are lower than the limit requirements of the relevant wastewater discharge standards. The tail water is collected by the liquid collection system and used for top water leaching in the tail liquid period.

[0135] (5) Backfill and seal the site

[0136] The first mud cake and the second mud cake are mixed, and the total mass of the first mud cake and the second mud cake is 100%, and the amount of lime added is 15% to obtain a mixed filler, which is backfilled at the bottom of the injection hole to a backfill height of 30 cm, and then the injection hole construction waste soil is backfilled thereon to plant plants.

[0137] The mother liquor adopts extraction process to recover rare earths, the mine product is rare earth liquid, and the production process is short; the collection and utilization of tail liquid is increased, and the rare earth recovery rate is 80%. Direct alkaline leaching leads to a lower rare earth recovery rate.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0139] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A green and low-carbon mining method integrating leaching and extraction of ionic rare earth mines, characterized in that: include: The treated liquid of the raffinate is mixed with the leaching agent and then injected into the leaching field through the injection hole for leaching in the leaching field, and a mother liquor is obtained after leaching reaction in an acidic environment. The mother liquor enters the desludging tank, and the first mud cake and the first supernatant are obtained after desludging; The tail water obtained by leaching the leaching period stope is injected into the tail liquid period stope through the injection hole, and the tail liquid is collected, and the tail liquid enters the desludging tank, and the second mud cake and the second supernatant are obtained after desludging; The second supernatant is concentrated to obtain a concentrate and produced water, and the produced water enters the eluent pool and is used as eluent water; The mixed liquid obtained by mixing the first supernatant and the concentrated liquid is extracted and stripped to obtain a rare earth feed liquid and the raffinate; The elution is a two-step elution, wherein the first step of elution is elution using the produced water, and the second step of elution is alkaline elution, and the tail water is collected.

2. The green and low-carbon mining method of an ionic rare earth mine with integrated leaching and extraction according to claim 1 is characterized in that: At least one of the following conditions is met: a. The rare earth ion concentration of the produced water is not higher than 10 mg / L; b. The rare earth ion concentration in the tail water is not higher than 100 mg / L.

3. The green and low-carbon mining method of an ionic rare earth mine with integrated leaching and extraction according to claim 2 is characterized in that: The eluent in the alkaline elution process is a mixture of the produced water and an alkaline solution, the pH value of the eluent is 8.5-9.0, and the alkaline solution includes sodium hydroxide.

4. The green and low-carbon mining method of an ionic rare earth mine with integrated leaching and extraction according to claim 1 is characterized in that: At least one of the following conditions is met: c. The leaching agent includes magnesium sulfate; d. The pH value of the acidic environment is 4.8-5.

0.

5. The green and low-carbon mining method of an ionic rare earth mine with integrated leaching and extraction according to claim 1 is characterized in that: When the rare earth ion concentration in the mother liquor is lower than 100 mg / L, the liquid collection is stopped.

6. The green and low-carbon mining method of an ionic rare earth mine with integrated leaching and extraction according to claim 1 is characterized in that: The concentration is membrane concentration, and the membrane concentration includes reverse osmosis membrane concentration.

7. The green and low-carbon mining method of ionic rare earth mines integrated with leaching and extraction according to claim 6 is characterized in that: The rare earth ion concentration in the concentrated solution after membrane concentration is not less than 400 mg / L.

8. The green and low-carbon mining method of ionic rare earth mines integrated with leaching and extraction according to claim 1 is characterized in that: At least one of the following conditions is met: e. The rare earth ion concentration in the mother liquor is not less than 200 mg / L; f. The rare earth ion concentration in the tail liquid is 100-200 mg / L; g. The rare earth ion concentration of the mixed solution is not less than 400 mg / L; h. The rare earth ion concentration of the tail water is not more than 100 mg / L; i. The turbidity of the first supernatant and the second supernatant is not higher than 1 NTU.

9. The green and low-carbon mining method of ionic rare earth mines integrated with leaching and extraction according to claim 1, characterized in that: The treated liquid is obtained by removing oil from the raffinate.

10. The green and low-carbon mining method of ionic rare earth mines integrated with leaching and extraction according to any one of claims 1 to 9, characterized in that: The method further comprises mixing the first mud cake and the second mud cake and then adding lime for backfilling, wherein the amount of lime added is 10%-20% based on the total mass of the first mud cake and the second mud cake being 100%.

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