阅读说明：本技术 一种串级淋洗离子型稀土尾矿中氨氮的工艺 (Process for cascade leaching of ammonia nitrogen in ionic rare earth tailings ) 是由 肖信锦 王慧娟 黄金 邓扬悟 谢芳芳 郭安 于 2021-09-15 设计创作，主要内容包括：本发明属于矿山环保治理领域,公开了一种串级淋洗离子型稀土尾矿中氨氮的工艺,其步骤包括：(1)配置淋洗液；(2)将硫酸铵原地浸矿后的离子型稀土尾矿按区域分为不同小区域,做好标识；(3)进行串级淋洗,以淋洗液中氨氮浓度小于15mg/L作为淋洗终点停止注液；(4)各区域淋洗达到淋洗终点后,再加入一次顶水将矿体中多余的淋洗剂洗脱出来,洗脱下来的洗水添加适量淋洗药剂配制成淋洗剂循环使用。本发明通过集中淋洗的方式,可以解决离子型稀土尾矿中残留氨氮在雨水淋滤等因素下导致的长期拖尾问题；通过串级淋洗的方式,可以降低淋洗过程中的药剂用量和液固比,降低淋洗药剂成本和后续氨氮废水处置成本。(The invention belongs to the field of environmental protection treatment of mines, and discloses a process for leaching ammonia nitrogen in ionic rare earth tailings in a cascade manner, which comprises the following steps: (1) preparing leacheate; (2) dividing the ionic rare earth tailings subjected to in-situ leaching of ammonium sulfate into different small areas according to areas, and marking; (3) performing cascade leaching, and stopping liquid injection by taking the ammonia nitrogen concentration in the leacheate as a leaching end point, wherein the ammonia nitrogen concentration is less than 15 mg/L; (4) and after the leaching of each area reaches the leaching end point, adding once top water to elute redundant leaching agent in the ore body, and adding a proper amount of leaching agent into eluted washing water to prepare the leaching agent for recycling. According to the invention, the problem of long-term tailing caused by factors such as rainwater leaching and the like of residual ammonia nitrogen in the ionic rare earth tailings can be solved through a centralized leaching mode; by means of cascade elution, the dosage of the agents and the liquid-solid ratio in the elution process can be reduced, and the cost of the elution agents and the subsequent cost of ammonia nitrogen wastewater treatment are reduced.)

1. A process method for cascade elution of ammonia nitrogen in ionic rare earth tailings is characterized by comprising the following steps:

(1) selecting environment-friendly electrolyte as an eluent, and adding water to prepare the eluent with a certain concentration;

(2) dividing the ionic rare earth tailings subjected to in-situ leaching of ammonium sulfate into different small areas ABCDE … … according to the areas, and marking;

(3) adding leacheate into the area A in batches for ammonia nitrogen leaching, transferring the leacheate collected by leaching for the 1 st time into a wastewater treatment tank, transferring the leacheate collected by leaching for the 2 nd time into the area B as the 1 st time leacheate of the area B for ammonia nitrogen leaching of the area B, transferring the leacheate collected by leaching for the 1 st time into the wastewater treatment tank, transferring the leacheate collected by leaching for the 3 rd time into the area A as the 2 nd time leacheate of the area B for ammonia nitrogen leaching of the area B, transferring the leacheate collected for the 2 nd time into the area C as the 1 st time leacheate of the area C for ammonia nitrogen leaching of the area C, transferring the leacheate collected for the 1 st time into the wastewater treatment tank, and repeating the steps to carry out cascade leaching, stopping the cascade leaching by taking the ammonia nitrogen concentration of the leacheate being less than 15mg/L as a leaching end point, and failing to leach to a leaching end point, supplementing new eluting agent and continuously eluting until the end point of elution;

(4) and after the leaching of each area reaches the leaching end point, adding once top water to elute redundant leaching agent in the ore body, and adding a proper amount of leaching agent into eluted washing water to prepare the leaching agent for recycling.

2. The process method for cascade elution of ammonia nitrogen in ionic rare earth tailings according to claim 1, wherein the elution process is cascade elution.

3. The process method for leaching ammonia nitrogen in ionic rare earth tailings in series according to claim 1, wherein the leaching agent is one or more of magnesium sulfate, potassium chloride, ferric sulfate, calcium chloride, aluminum sulfate and the like.

4. The process method for cascade leaching of ammonia nitrogen in ionic rare earth tailings according to claim 1, wherein the mass concentration of the leacheate is 1-10%.

5. The process method for cascade leaching of ammonia nitrogen in ionic rare earth tailings according to claim 1, wherein the leaching solution is injected in a normal-temperature normal-pressure natural leaching manner.

Technical Field

The invention belongs to the field of environmental protection treatment of mines, and relates to a process for leaching ammonia nitrogen in ionic rare earth tailings in a cascade manner.

Background

The ionic rare earth ore is rich in indispensable medium-heavy rare earth elements in high-tech industrial fields such as national defense and military industry, new materials, aerospace and the like, and is a non-renewable mineral resource which is globally acknowledged to be concerned with the development of new industries. The ionic rare earth ore extraction process is developed to date, and an ammonium salt system in-situ ore leaching process of ammonium sulfate leaching-ammonium bicarbonate precipitation is commonly adopted. The ammonium sulfate as the mineral leaching agent has a series of advantages of low production cost, high rare earth leaching rate, low impurity content of leaching liquid, high purity of rare earth products and the like, but a large amount of ammonium roots are remained in tailings left after mineral leaching, and are gradually released to the surrounding environment under the action of factors such as rainwater leaching and the like, so that the ammonia nitrogen content in the soil and water in a mining area exceeds the standard for a long time. The ionic rare earth mine usually relates to a large soil area, and residual ammonium salt is difficult to remove by adopting a surface soil removal method, a solidification method and other traditional soil remediation technologies. The clear water is commonly adopted in the industry to leach the mine to remove ammonia nitrogen, but the clear water is long in injection time, large in dosage and incomplete in leaching, and part of ammonium salt residues are still slowly released along with rainfall after the mine is washed, so that the surrounding environment is polluted.

Aiming at the problem, the department of ecological environment has already required that all ionic rare earth mining areas in the Gannan region stop production comprehensively in 2014, and the environmental protection problem of the generated ammonia nitrogen is solved, the existing mining area adopts a method of establishing a tail water treatment station to pump surface water in a water area around the mining area to a disposal station for denitrification and then discharge the surface water, 8 ammonia nitrogen tail water treatment stations with total treatment amount of about 80000t/d per day are established, the annual operating cost is more than one hundred million yuan, and the treatment cost is high. In recent years, researchers put forward the idea that ammonia nitrogen in ion type rare earth tailings needs to be solved from the source, and relevant research on removal of ammonia nitrogen in tailings is carried out, and researches find that the residual mechanism of ammonium ions in the tailings is similar to that of rare earth ions, and the ammonium ions in the tailings can be quickly removed in a leaching mode of potassium chloride and other ion type leaching agents, so that the problem of slow release of the ammonium ions in the tailings can be solved.

Therefore, an economically feasible ionic rare earth tailing ammonia nitrogen leaching process is urgently needed to be developed, the dosage and water amount of leaching agents are optimized while ammonia nitrogen is leached efficiently, leaching cost is reduced, and the problem of ammonia nitrogen pollution is solved.

The existing ionic type rare earth tailing ammonia nitrogen treatment process is to intensively extract surface water polluted by ammonia nitrogen for denitrification treatment by a way of establishing a tailing water treatment station; researchers also explore the effect of different eluting agents on the concentrated elution of ammonia nitrogen from ionic rare earth tailings.

The existing process has the disadvantages of large water volume of wastewater obtained by leaching and slow release, long tailing time, great difficulty in wastewater collection, extreme lack of organic carbon source in leached rainwater, addition of a large amount of organic carbon source in the process of adopting a nitrification/denitrification treatment process in a tail water treatment station, and high treatment cost; the problem of long-term tailing of ammonia nitrogen can be solved by adopting the eluting agent to intensively elute the residual ammonia nitrogen in the ionic rare earth tailings, but the dosage of the eluting agent is larger, the solid content of the eluting solution is higher, and the treatment cost is still higher.

Disclosure of Invention

The invention aims to develop a process method for quickly, effectively and low-cost removing residual ammonia nitrogen in tailings of ion type rare earth ores after leaching by using ammonium sulfate, and solve the problem that the ammonia nitrogen in the ion type rare earth tailings is trailing for a long time under the factors of rainwater leaching and the like.

In order to achieve the above object, the present invention provides the following technical solutions: a process method for cascade leaching of ammonia nitrogen in ionic rare earth tailings comprises the following steps:

(1) selecting environment-friendly electrolyte as an eluent, and preparing the eluent with a certain concentration according to process requirements;

(2) dividing the ionic rare earth tailings subjected to in-situ leaching of ammonium sulfate into different small areas ABCDE … … according to the areas, and marking;

(3) adding leacheate into the area A in batches for ammonia nitrogen leaching, transferring the leacheate collected by leaching for the 1 st time into a wastewater treatment tank, transferring the leacheate collected by leaching for the 2 nd time into the area B as the 1 st time leacheate of the area B for ammonia nitrogen leaching of the area B, transferring the leacheate collected by leaching for the 1 st time into the wastewater treatment tank, transferring the leacheate collected by leaching for the 3 rd time into the area A as the 2 nd time leacheate of the area B for ammonia nitrogen leaching of the area B, transferring the leacheate collected for the 2 nd time into the area C as the 1 st time leacheate of the area C for ammonia nitrogen leaching of the area C, transferring the leacheate collected for the 1 st time into the wastewater treatment tank, and repeating the steps to carry out cascade leaching, stopping the cascade leaching by taking the ammonia nitrogen concentration of the leacheate being less than 15mg/L as a leaching end point, and failing to leach to a leaching end point, supplementing new eluting agent and continuously eluting until the end point of elution;

(4) and after the leaching of each area reaches the leaching end point, adding once top water to elute redundant leaching agent in the ore body, and adding a proper amount of leaching agent into eluted washing water to prepare the leaching agent for recycling.

Preferably, the elution mode of the eluent is cascade elution.

Preferably, the leaching agent is one or more of magnesium sulfate, potassium chloride, ferric sulfate, calcium chloride, aluminum sulfate and the like.

Preferably, the eluent has a mass concentration of 1% to 10%.

Preferably, the leaching solution is injected by natural leaching at normal temperature and normal pressure.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the invention, the problem of long-term tailing caused by factors such as rainwater leaching and the like of residual ammonia nitrogen in the ionic rare earth tailings can be solved through a centralized leaching mode;

(2) by means of cascade elution, the dosage of the agents and the liquid-solid ratio in the elution process can be reduced, and the cost of the elution agents and the subsequent cost of ammonia nitrogen wastewater treatment are reduced.

Drawings

FIG. 1 is a flow diagram of a cascade leaching process of the present invention;

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

The invention provides a process method for cascade leaching of ammonia nitrogen in ionic rare earth tailings, which comprises the following steps:

(1) selecting environment-friendly electrolyte as an eluent, and preparing the eluent with a certain concentration according to process requirements;

(2) dividing the ionic rare earth tailings subjected to in-situ leaching of ammonium sulfate into different small areas ABCDE … … according to the areas, and marking;

(3) adding leacheate into the area A in batches for ammonia nitrogen leaching, transferring the leacheate collected by leaching for the 1 st time into a wastewater treatment tank, transferring the leacheate collected by leaching for the 2 nd time into the area B as the 1 st time leacheate of the area B for ammonia nitrogen leaching, transferring the leacheate collected by leaching for the 1 st time into the wastewater treatment tank, transferring the leacheate collected by leaching for the 3 rd time into the area B as the 2 nd time leacheate of the area B for ammonia nitrogen leaching of the area B, transferring the leacheate collected for the 2 nd time into the area C as the 1 st time leacheate of the area C for ammonia nitrogen leaching of the area C, transferring the leacheate collected for the 1 st time into the wastewater treatment tank, and performing cascade leaching by analogy, and stopping leaching by using ammonia nitrogen concentration of the leacheate which is less than 15mg/L (emission standard of rare earth industrial pollutants (GB26451-2011) ammonia nitrogen direct emission standard), if the cascade elution is not eluted to the elution end point, supplementing a new eluent to continuously elute to the elution end point;

(4) and after the leaching of each area reaches the leaching end point, adding once top water to elute redundant leaching agent in the ore body, and adding a proper amount of leaching agent into eluted washing water to prepare the leaching agent for recycling.

The invention also comprises the detection of the ammonia nitrogen concentration of the leachate. The device and the method for detecting the ammonia nitrogen concentration have no special requirements, and the device and the method for detecting the ammonia nitrogen concentration, which are well known by the technical personnel in the field, can be used. In the invention, in the leaching time range of the invention, when the ammonia nitrogen concentration of the leachate is less than or equal to 15mg/L, the leaching operation is stopped.

In the invention, the liquid injection mode of the leacheate is cascade leaching.

In the invention, the leaching agent is one or more of magnesium sulfate, potassium chloride, ferric sulfate, calcium chloride, aluminum sulfate and the like, and is selected by combining the actual soil condition of a mining area.

In the present invention, the mass concentration of the eluent is 1 to 10 wt%, and the magnesium sulfate solution is preferably 2 wt% as the eluent.

In the invention, the liquid injection mode of the leacheate is normal-temperature normal-pressure natural leaching.

According to the invention, the problem of long-term tailing caused by factors such as rainwater leaching and the like of residual ammonia nitrogen in the ionic rare earth tailings can be solved through a centralized leaching mode; by means of cascade elution, the dosage of the agents and the liquid-solid ratio in the elution process can be reduced, and the cost of the elution agents and the subsequent cost of ammonia nitrogen wastewater treatment are reduced.

The following will explain the process method for in-situ de-cascade leaching of ammonia nitrogen in ionic rare earth tailings by using the eluent in accordance with the embodiments in detail, but they should not be construed as limiting the scope of the present invention.

The raw ore of an ionic rare earth mine in Ganzhou city in Jiangxi province is collected to a laboratory for ionic rare earth simulated leaching and tailing cascade leaching after leaching. And (3) simulating the mine field leaching and leaching process by adopting an ion exchange column. The exchange columns are cylindrical, a large column with the inner diameter of 10 cm and the height of 100 cm is used for leaching the ores during leaching, a small column with the inner diameter of 2 cm and the height of 10 cm is used for leaching during leaching, and the two exchange columns are made of organic glass.

The rare earth content of the ionic rare earth ore is 0.13 wt%, the ore soil is air-dried, crushed and sieved by a 20-mesh sieve, then the ore soil with a certain mass is weighed and loaded into an ore leaching column, the ore leaching is carried out by adopting 2 wt% ammonium sulfate solution, the liquid injection is stopped when no rare earth is detected in the ore leaching liquid, and the ionic rare earth tailings in the column are dried to constant weight for later use.

Example 1:

the cascade leaching experimental process of simulating the ionic rare earth tailings by using ammonium sulfate as a leaching agent comprises the following steps:

(1) weighing ionic rare earth tailing ore soil with a certain mass, mashing the ionic rare earth tailing ore soil, sieving the mashed ionic rare earth tailing ore soil with a 20-mesh sieve, uniformly mixing, respectively weighing 40g of the treated ionic rare earth tailing ore soil, filling the ionic rare earth tailing ore soil into the same four exchange columns, numbering A/B/C/D, and respectively adding 20ml of deionized water to wet the ore soil so as to be beneficial to subsequent full leaching;

(2) adding a magnesium sulfate solution with the mass concentration of 2% into the column A for leaching for several times, wherein the liquid injection amount is 50ml each time, the liquid collection amount is 50ml, the serial numbers of A1, A2, A3 and … … are used for respectively measuring the ammonia nitrogen concentration in the leacheate, and the liquid injection is stopped when the ammonia nitrogen concentration of the leacheate is less than 15 mg/L;

(3) according to the cascade leaching process, the second leaching solution of the column A is used as the first leaching solution of the column B for leaching, the number of the collected solution is A2-B1, the leaching of the column C and the column D is carried out by analogy, and the leaching results are shown in the following table:

cascade elution data

Dosage of leaching agent is compared with that of water

And calculating the dosage of magnesium sulfate and the dosage of water required by leaching by using the column A as a single leaching solution, wherein 300ml of the leaching solution required by the group A, 6g of magnesium sulfate and 300ml of water are used by using 300ml of the leaching solution required by the group A as a leaching end point when the ammonia nitrogen concentration in the leaching solution is less than 15 mg/L. And in the B/C/D column cascade leaching, in addition to recycling the previous group of leacheate, 150ml of new leacheate needs to be additionally added when the leaching end point is less than 15mg/L, the consumption of the magnesium sulfate and the consumption of water which are newly added are respectively 3g and 150ml and are only half of the group A. Compared with the single leaching, the consumption of cascade leaching magnesium sulfate is reduced by half, and the consumption of water is reduced by half, which means that the consumption of ammonia nitrogen wastewater to be treated is reduced by half correspondingly, and the wastewater treatment cost is greatly reduced while the consumption of leaching agents is reduced.

Example 2

The experimental process for simulating the cascade leaching of the ionic rare earth tailings by using potassium chloride as a leaching agent comprises the following steps:

(1) weighing ionic rare earth tailing ore soil with a certain mass, mashing the ionic rare earth tailing ore soil, sieving the mashed ionic rare earth tailing ore soil with a 20-mesh sieve, uniformly mixing, respectively weighing 40g of the treated ionic rare earth tailing ore soil, filling the ionic rare earth tailing ore soil into the same four exchange columns, numbering A/B/C/D, and respectively adding 20ml of deionized water to wet the ore soil so as to be beneficial to subsequent full leaching;

(2) adding a potassium chloride solution with the mass concentration of 2% into the column A for leaching for several times, wherein the liquid injection amount is 50ml each time, the liquid collection amount is 50ml, the serial numbers of A1, A2, A3 and … … are used for respectively measuring the ammonia nitrogen concentration in the leacheate, and the liquid injection is stopped when the ammonia nitrogen concentration of the leacheate is less than 15 mg/L;

(3) according to the cascade leaching process, the second leaching solution of the column A is used as the first leaching solution of the column B for leaching, the number of the collected solution is A2-B1, the leaching of the column C and the column D is carried out by analogy, and the leaching results are shown in the following table:

cascade elution data

Dosage of leaching agent is compared with that of water

And calculating the potassium chloride dosage and the water dosage required by leaching by taking the column A as independent leaching, wherein 400ml of the leaching solution required by the group A, 8g of the potassium chloride dosage and 400ml of the water dosage are determined by taking the ammonia nitrogen concentration in the leaching solution of less than 15mg/L as a leaching end point. And in the B/C/D column cascade leaching, in addition to recycling the previous group of leacheate, 200ml of new leacheate needs to be additionally added when the leaching end point is less than 15mg/L, the consumption of the newly added potassium chloride and the consumption of water are respectively 4g and 200ml, and are only half of the group A. Compared with the single leaching, the use amount of the potassium chloride and the water in the cascade leaching is reduced by 50%, which means that the amount of the ammonia nitrogen wastewater to be treated is correspondingly reduced by 50%, and the wastewater treatment cost is greatly reduced while the use amount of the leaching agent is reduced.

Example 3

The cascade leaching experimental process of the ionic rare earth tailings by taking ferric sulfate as a leaching agent comprises the following steps:

(1) weighing ionic rare earth tailing ore soil with a certain mass, mashing the ionic rare earth tailing ore soil, sieving the mashed ionic rare earth tailing ore soil with a 20-mesh sieve, uniformly mixing, respectively weighing 40g of the treated ionic rare earth tailing ore soil, filling the ionic rare earth tailing ore soil into the same four exchange columns, numbering A/B/C/D, and respectively adding 20ml of deionized water to wet the ore soil so as to be beneficial to subsequent full leaching;

(2) adding a ferric sulfate solution with the mass concentration of 2% into the column A for leaching for several times, wherein the liquid injection amount is 50ml each time, the liquid collection amount is 50ml, the serial numbers of A1, A2, A3 and … … are used for respectively measuring the ammonia nitrogen concentration in the leacheate, and the liquid injection is stopped when the ammonia nitrogen concentration of the leacheate is less than 15 mg/L;

(3) according to the cascade leaching process, the second leaching solution of the column A is used as the first leaching solution of the column B for leaching, the number of the collected solution is A2-B1, the leaching of the column C and the column D is carried out by analogy, and the leaching results are shown in the following table:

cascade elution data

Dosage of leaching agent is compared with that of water

And calculating the dosage of ferric sulfate and the dosage of water required by leaching by using the column A as a single leaching solution, wherein 300ml of the leaching solution required by the group A, 6g of ferric sulfate and 300ml of water are used by using 300ml of the leaching solution required by the group A as a leaching end point when the ammonia nitrogen concentration in the leaching solution is less than 15 mg/L. And in the B/C/D column cascade leaching, except the last group of leacheate is recycled, 100ml of new leacheate needs to be additionally added when the leaching end point is reached to less than 15mg/L, and the dosage of the newly added ferric sulfate and the dosage of water are respectively 2g and 100ml and are only one third of the dosage of the group A. Compared with the single leaching, the use amount of the potassium chloride and the water in the cascade leaching is reduced by 66.67 percent, which means that the amount of the ammonia nitrogen wastewater to be treated is correspondingly reduced by 66.67 percent, and the wastewater treatment cost is greatly reduced while the use amount of the leaching agent is reduced.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.