阅读说明：本技术 一种含钙镁浸取液制取含钙产品及含镁产品的方法 (Method for preparing calcium-containing product and magnesium-containing product from calcium-containing magnesium leaching solution ) 是由 方进 黄德明 顾春光 孟品品 于 2021-01-04 设计创作，主要内容包括：本发明公开了一种含钙镁浸取液制取含钙产品及含镁产品的方法,属于化工技术领域。其包括以下步骤：将硫酸钾溶液和含钙镁浸取液进行脱钙反应,反应后第一次固液分离,分离得到硫酸钙和第一液体,第一液体与碳酸氢铵以及氨反应,反应后进行第二次固液分离,分离所得的第二液体浓缩造粒后得到硝酸钾镁,分离所得的第二固体与硝酸反应,得到硝酸镁。含钙镁浸取液由中低品位磷矿制备低镁磷精矿过程中压滤分离所获得到。该方法能有效地将化学选矿副产的含钙镁浸取液进行钙镁分离,同时得到硫酸钙、硝酸钾镁及硝酸镁,提高了化学选矿副产物的利用价值,扩大了该类化学选矿副产物的应用范围。(The invention discloses a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, belonging to the technical field of chemical industry. Which comprises the following steps: decalcification reaction is carried out on a potassium sulfate solution and a calcium-magnesium-containing leaching solution, first solid-liquid separation is carried out after the reaction, calcium sulfate and first liquid are obtained through separation, the first liquid reacts with ammonium bicarbonate and ammonia, second solid-liquid separation is carried out after the reaction, potassium magnesium nitrate is obtained after second liquid obtained through separation is concentrated and granulated, and second solid obtained through separation reacts with nitric acid to obtain magnesium nitrate. The leaching solution containing calcium and magnesium is obtained by filter pressing and separation in the process of preparing low-magnesium phosphate concentrate from medium and low-grade phosphate ore. The method can effectively separate calcium and magnesium from the calcium and magnesium containing leaching solution which is a byproduct of chemical beneficiation, and simultaneously obtain calcium sulfate, potassium magnesium nitrate and magnesium nitrate, thereby improving the utilization value of the chemical beneficiation by-product and expanding the application range of the chemical beneficiation by-product.)

1. A method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution is characterized by comprising the following steps:

performing decalcification reaction on a potassium sulfate solution and a calcium-magnesium-containing leaching solution, performing first solid-liquid separation after the reaction to obtain a first liquid and calcium sulfate, reacting the first liquid with ammonium bicarbonate and ammonia, performing second solid-liquid separation after the reaction, concentrating and granulating the separated second liquid to obtain potassium magnesium nitrate, and performing neutralization reaction on the separated second solid and nitric acid to obtain magnesium nitrate;

wherein the calcium and magnesium containing leaching solution mainly contains calcium magnesium ammonium nitrate.

2. The method of claim 1, wherein the calcium-containing magnesium leachate is concentrated and then reacted with the potassium sulfate solution;

preferably, the concentration of the concentrated calcium magnesium ammonium nitrate is greater than 25 wt%.

3. The method as claimed in claim 1, wherein the reaction temperature of the potassium sulfate solution and the leaching solution containing calcium and magnesium is 20-110 ℃, and the reaction time is 3-6 h;

preferably, the concentration of the potassium sulfate solution is 20-50 wt%, and the mass ratio of the potassium sulfate solution to the calcium-containing magnesium leaching solution is 1-5: 1-7.

4. The method of claim 1, further comprising washing the calcium sulfate.

5. The method of claim 4, wherein the washing comprises a first washing and a second washing, wherein a first washing solution after the first washing is used for dissolving the potassium sulfate of the next batch, and a second washing solution after the second washing is used as a washing solution for the first washing process of the next batch.

6. The method of claim 1, wherein the first liquid is reacted with the ammonium bicarbonate and the ammonia at a temperature of 35-80 ℃ for a time of 1.5-3 hours;

preferably, the concentration of the ammonium bicarbonate is 95-99 wt%, the purity of the ammonia is not lower than 99 wt%, and the mass ratio of the first liquid to the ammonium bicarbonate and the ammonia is 1-4:1-5: 0.2-1.5.

7. The method of claim 1, further comprising, prior to said second liquid being granulated, subjecting said second liquid to a preheating operation;

preferably, the preheating treatment temperature is controlled at 105-115 ℃, and the preheating time is 5-15 s.

8. The method of claim 7, wherein prior to said second liquid granulating, further comprising heating after preheating;

preferably, the heating temperature is 120-140 ℃, and the heating time is 5-15 s.

9. The method of claim 8, wherein prior to said second liquid granulating, further comprising evaporating and separating the heated material;

preferably, the temperature of the second liquid during evaporation is 140-165 ℃;

preferably, the separation is carried out by flash separation.

10. The method as claimed in claim 9, further comprising cooling the remaining material after separation to remove gas to a temperature of 100-120 ℃.

Technical Field

The invention relates to the technical field of chemical industry, in particular to a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution.

Background

At present, the solid obtained by calcining ground phosphate rock is generally used for being mixed with nitric acid and ammonium nitrate solution for leaching, low-magnesium phosphorus fine powder is obtained by filtering after leaching, and magnesium-containing calcium carbonate can be obtained by drying after the filtrate reacts with ammonium carbonate.

However, the magnesium-containing calcium carbonate mixture obtained by the method has low utilization value, the application range is greatly limited, the actual production difficulty is high, the conversion rate of filtrate is low, the product content is unstable, and the magnesium-containing calcium carbonate is wasted due to the fact that the magnesium-containing calcium carbonate cannot be effectively utilized.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, so as to solve the technical problems.

The application can be realized as follows:

the application provides a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, which comprises the following steps:

the method comprises the following steps of carrying out decalcification reaction on a potassium sulfate solution and a calcium-magnesium-containing leaching solution, carrying out first solid-liquid separation after the reaction, obtaining a first liquid and calcium sulfate through separation, reacting the first liquid with ammonium bicarbonate and ammonia, carrying out second solid-liquid separation after the reaction, concentrating and granulating a second liquid obtained through the separation to obtain potassium magnesium nitrate, and carrying out neutralization reaction on a second solid obtained through the separation and nitric acid to obtain magnesium nitrate.

Wherein the calcium and magnesium containing leaching solution mainly contains calcium magnesium ammonium nitrate.

In an alternative embodiment, the calcium-magnesium containing leachate is concentrated and then reacted with a potassium sulfate solution.

In an alternative embodiment, the concentration of the concentrated calcium magnesium ammonium nitrate is greater than 25 wt%.

In an alternative embodiment, the reaction temperature of the potassium sulfate solution and the calcium-magnesium containing leaching solution is 20-110 ℃, and the reaction time is 3-6 h.

In an alternative embodiment, the concentration of the potassium sulfate solution is 20-50 wt%, and the mass ratio of the potassium sulfate solution to the calcium-magnesium containing leaching solution is 1-5: 1-7.

In an alternative embodiment, washing the calcium sulfate is also included.

In an alternative embodiment, the washing includes a first washing and a second washing, the first washing after the first washing is used for dissolving the next batch of potassium sulfate, and the second washing after the second washing is used as a washing liquid for the next batch of the first washing.

In an alternative embodiment, the first liquid is reacted with the ammonium bicarbonate and ammonia at a temperature of from 35 ℃ to 80 ℃ for a time of from 1.5h to 3 h.

In an alternative embodiment, the concentration of ammonium bicarbonate is 95-99 wt%, the purity of ammonia is not less than 99 wt%, and the mass ratio of the first liquid to the ammonium bicarbonate and ammonia is 1-4:1-5: 0.2-1.5.

In an alternative embodiment, before the second liquid is granulated, a preheating operation of the second liquid is further included.

In an alternative embodiment, the preheating temperature is controlled to be 105 ℃ and 115 ℃ and the preheating time is 5-15 s.

In an alternative embodiment, the second liquid is heated after preheating before granulating.

In an alternative embodiment, the heating temperature is 120-140 ℃ and the heating time is 5-15 s.

In an alternative embodiment, before the second liquid is granulated, evaporating and separating the heated material.

In an alternative embodiment, the temperature of the second liquid during evaporation is 140-165 ℃.

In an alternative embodiment, the separation is performed as a flash separation.

In an alternative embodiment, the separation further comprises cooling the remaining material with the gas removed to 100-120 ℃.

The beneficial effect of this application includes:

calcium sulfate is obtained by performing decalcification reaction on a calcium-magnesium-containing leaching solution and a potassium sulfate solution, the first liquid obtained after the reaction separation is further reacted with ammonium bicarbonate and ammonia, the second liquid obtained after the reaction separation is concentrated and granulated to obtain potassium magnesium nitrate and a second solid, and the second solid is further reacted with nitric acid to obtain magnesium nitrate, so that the calcium-magnesium-containing leaching solution which is a byproduct of chemical beneficiation can be effectively subjected to calcium-magnesium separation, calcium sulfate, potassium magnesium nitrate and magnesium nitrate are obtained at the same time, the utilization value of the chemical beneficiation byproduct is improved, and the application range of the chemical beneficiation byproduct is expanded.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a flow chart of a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution provided by the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The method for preparing the calcium-containing product and the magnesium-containing product from the leaching solution containing calcium and magnesium provided by the application is specifically explained below.

The application provides a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, and the method comprises the following steps of:

decalcification reaction is carried out on a potassium sulfate solution and a calcium-magnesium-containing leaching solution, first solid-liquid separation is carried out after the reaction to obtain a first liquid and calcium sulfate through separation, the first liquid reacts with ammonium bicarbonate and ammonia, second solid-liquid separation is carried out after the reaction, potassium magnesium nitrate is obtained after granulation of a second liquid obtained through separation, and neutralization reaction is carried out on a second solid obtained through separation and nitric acid to obtain magnesium nitrate.

Wherein the main component of the calcium and magnesium containing leaching solution is calcium ammonium magnesium nitrate. The calcium-magnesium-containing leaching solution is obtained by filter pressing and separating in the process of preparing low-magnesium phosphate concentrate from medium and low-grade phosphate ore, and P of the medium and low-grade phosphate ore₂O₅P content of 10-30 wt% low-magnesium phosphate concentrate₂O₅Not less than 34.5 wt% and not more than 0.85 wt% of MgO.

The low-magnesium phosphate concentrate is prepared by taking middle-low grade phosphate ore as a raw material through the working procedures of crushing, calcining, leaching, filter pressing separation and the like, and liquid discharged by a filter press in the process is used as calcium-magnesium-containing leaching liquid.

In an alternative embodiment, the calcium-magnesium containing leachate is concentrated and then reacted with a potassium sulfate solution.

It is referred to as concentrating until the concentration of ammonium calcium magnesium nitrate is more than 25 wt% and then reacting with potassium sulfate solution.

The concentration may be carried out by pumping the calcium and magnesium containing leachate to a concentration system, such as a two-way counter-current evaporator.

Further, the concentrated leaching solution containing calcium and magnesium is pumped into a decalcification tank to react with the potassium sulfate solution from the potassium sulfate dissolving tank, and the process can be called as a decalcification process. The process involves the reaction equation:

2K₂SO₄+Ca(NO₃)₂﹒Mg(NO₃)₂﹒xH₂O﹒NH₄NO₃→CaSO₄↓+4KNO₃+Mg(NO₃)₂﹒xH₂O+NH₄NO₃. Wherein, the value of x is 3-8.

In alternative embodiments, the potassium sulfate solution used in the reaction may have a concentration of 20 to 50 wt%, such as 20 wt%, 30 wt%, 40 wt%, or 50 wt%, etc. The potassium sulfate can be dissolved and measured by water, and then conveyed to a dissolving tank by a bucket elevator, and then conveyed to a decalcification working section after being stirred and dissolved.

In alternative embodiments, the mass ratio of the potassium sulfate solution to the calcium-containing magnesium leachate may be 1-5:1-7, such as 1:1, 1:5, 1:7, 3:1, 3:5, 3:7, 5:1, 5:3, or 5:7, etc.

In alternative embodiments, the reaction temperature of the potassium sulfate solution and the calcium and magnesium containing leachate may be 20-110 ℃, such as 20 ℃, 40 ℃, 50 ℃, 80 ℃, 100 ℃ or 110 ℃, etc. The reaction time can be 3-6h, such as 3h, 4h, 5h or 6 h.

And (3) carrying out first solid-liquid separation on the slurry after the decalcification reaction to obtain a first solid and a first liquid (called decalcification liquid) through separation. The first solid is calcium sulfate. In reference, the first solid-liquid separation can be to send the feed liquid to a filter by a pump, obtain the first solid as a filter cake after filtering, and enter the subsequent magnesium precipitation process by the decalcification liquid.

In an alternative embodiment, the first solid is washed with water. The washing of the first solid includes a first washing (referred to as a first washing) and a second washing (referred to as a second washing), and a washing liquid (referred to as a first washing liquid or a first washing liquid) after the first washing is used for dissolving the next batch of potassium sulfate, that is, the first washing liquid or the first washing liquid can be pumped into a potassium sulfate dissolving tank to dissolve the next batch of potassium sulfate. And (3) washing the solid after the first washing for the second time, wherein the solid after the second washing is calcium sulfate with higher purity, and correspondingly, drying and crushing the solid to obtain a calcium sulfate product with higher purity (CaO is more than or equal to 39 wt%). The wash solution after the second wash (referred to as the second wash solution or second wash solution) is recycled as the wash solution for the first wash process of the next batch.

The first liquid (decalcified liquid) obtained from the above separation is reacted with ammonium bicarbonate and ammonia, and the process can be called magnesium precipitation process. The process involves the reaction equation:

NH₃+NH₄HCO₃→(NH₄)₂CO₃；

Mg(NO₃)₂﹒6H₂O+(NH₄)₂CO₃→MgCO₃↓+2NH₄NO₃+6H₂O。

in alternative embodiments, the reaction temperature of the first liquid with the ammonium bicarbonate and ammonia may be 35-80 ℃, such as 35 ℃, 50 ℃, 60 ℃, or 80 ℃, and the like. The reaction time can be 1.5-3h, such as 1.5h, 2h, 2.5h or 3 h.

In alternative embodiments, the ammonium bicarbonate concentration may be 95-99 wt%, such as 95 wt%, 96 wt%, 97 wt%, 98 wt%, or 99 wt%, etc., with ammonia purity no less than 99 wt%. The mass ratio of the first liquid to the ammonium bicarbonate and ammonia may be 1-4:1-5: 0.2-1.5.

The ammonium bicarbonate and ammonia preferably form two ammonium solutions prior to reaction with the first liquid. The two ammonium solutions can be prepared in the following way: and (3) metering ammonium bicarbonate, sending the ammonium bicarbonate to an ammonium bicarbonate dissolving tank, adding washing liquor obtained by the second solid-liquid separation for dissolving, pumping the ammonium bicarbonate liquid to a jet absorber, and introducing gas ammonia for absorption to obtain two ammonium liquids.

Subsequently, the decalcified solution and the two ammonium solutions were simultaneously fed to a reaction tank, and reacted under the above-mentioned reaction conditions. And carrying out secondary solid-liquid separation on the slurry obtained by the reaction to obtain a second solid-liquid and a second liquid (named as magnesium precipitation liquid). In reference, the second solid-liquid separation may be to send the feed liquid to a filter by a pump, and the second solid obtained after filtration is used as a filter cake, and the second liquid (magnesium precipitation liquid) enters the subsequent granulation process. In an alternative embodiment, a water washing step may be further performed after the second solid-liquid separation, the filtrate after the water washing is used to obtain magnesium potassium nitrate, and the filter cake after the water washing is used to obtain magnesium nitrate.

In an alternative embodiment, the magnesium nitrate may be obtained by reacting a slurry obtained by mixing the second solid with water with nitric acid. Specifically, the magnesium nitrate can be obtained by the following method: and (3) scattering part or all of the second solid (in the form of filter cake) obtained after the second solid-liquid separation by using a scattering device, sending the second solid to a neutralization tank, adding water to prepare slurry, adding nitric acid to neutralize, and concentrating to obtain a magnesium nitrate product. The condensate produced by the concentration system is used for the filter press washing water.

The magnesium potassium nitrate can be obtained by the following method: and granulating, cooling, screening and wrapping the second liquid (magnesium precipitation liquid) obtained by the second solid-liquid separation to obtain the potassium magnesium nitrate product.

In an alternative embodiment, before the second liquid is granulated, a preheating operation of the second liquid is further included. The preheating temperature may be, for example, 105 ℃ to 115 ℃ and the preheating time may be 5 to 15 seconds.

Further, heating is performed after preheating. The heating temperature can be, for example, 120 ℃ to 140 ℃ and the heating time can be, for example, 5 to 15 seconds.

Further, before the second liquid granulation, the method also comprises evaporating and separating the heated materials. The temperature of the second liquid during evaporation may be, for example, 140 ℃ to 165 ℃, such as 140 ℃, 150 ℃, 160 ℃ or 165 ℃.

In an alternative embodiment, the separation may be performed as a flash separation.

Furthermore, the method also comprises the step of cooling the residual material after the separation and the removal of the gas to 100-120 ℃, such as 100 ℃, 110 ℃ or 120 ℃ and the like.

In particular, reference may be made to: the magnesium deposition liquid from the magnesium deposition filtering and washing process is sent to a preheater by a pump (condensate generated by medium-pressure steam is used as a heating medium), the preheated material enters a heat exchanger (evaporated magnesium deposition liquid is used as a heating medium) to be heated, then enters a forced circulation type evaporator (the temperature of the evaporated material liquid is 140-165 ℃) to be evaporated, the evaporated material is separated by a flash separator and then enters a granulation feeding tank to be concentrated, the concentrated liquid is reduced to the optimal granulation temperature of 100-120 ℃ after heat exchange through the heat exchanger, and then is sent to a granulator for granulation, cooling, screening and packaging to obtain a potassium magnesium nitrate product. The condensate produced in the concentration process can be used for washing water of the filter.

It is worth to be noted that, in the method, the decalcification and the demagging processes can be carried out by adopting a tank reactor with stirring, the repulping tank can adopt a three-stage series tank with stirring, the filtering can adopt a rotary table filter, a vacuum filter, a tilting disc filter or a belt filter, and the centrifugal separation can adopt a centrifuge.

On the basis, the calcium and magnesium containing leaching solution which is a byproduct of chemical beneficiation can be effectively subjected to calcium and magnesium separation by the method, and meanwhile, calcium sulfate, potassium magnesium nitrate and magnesium nitrate are obtained, so that the utilization value of the chemical beneficiation byproduct is improved, and the application range of the chemical beneficiation byproduct is expanded.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment provides a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, which comprises the following specific steps:

after being measured, the potassium sulfate is conveyed to a dissolving tank through a bucket elevator, and is conveyed to a decalcification tank after being stirred and dissolved. With P₂O₅The medium-low grade phosphorite with the content of 10-30 wt% is used as a raw material to prepare P through the working procedures of crushing, calcining, leaching, filter pressing separation and the like₂O₅The low-magnesium phosphate concentrate with the weight percent of more than or equal to 34.5 percent and the weight percent of MgO less than or equal to 0.85 percent, and the liquid discharged by a filter press in the process is used as the leaching solution containing calcium and magnesium.

Pumping the calcium-magnesium-containing leaching solution into a two-effect countercurrent evaporation device for concentration until the concentration of calcium magnesium ammonium nitrate is 28 wt%, and then pumping the concentrated calcium-magnesium-containing leaching solution into a decalcification tank for reaction with a potassium sulfate solution from a potassium sulfate dissolving tank. The concentration of the potassium sulfate solution used in the reaction is 20 wt%, and the mass ratio of the potassium sulfate solution to the calcium magnesium ammonium nitrate concentrated solution is 1: 1. The reaction temperature of the potassium sulfate solution and the concentrated solution of calcium magnesium ammonium nitrate is 65 ℃, and the reaction time is 4.5 h.

And pumping the slurry after the decalcification reaction into a filter for first solid-liquid separation to obtain a first solid (in the form of a filter cake) and a first liquid (called decalcification liquid).

And (3) carrying out primary washing (primary washing) and secondary washing (secondary washing) on the first solid by using water, and drying and crushing the solid after the secondary washing to obtain a corresponding calcium sulfate product. Wherein, the washing liquid (first washing liquid) after the first washing is used for dissolving the potassium sulfate of the next batch, and the washing liquid (second washing liquid) after the second washing is used as the washing liquid for recycling in the first washing process of the next batch.

And (3) metering ammonium bicarbonate, then sending the ammonium bicarbonate to an ammonium bicarbonate dissolving tank for dissolving, pumping the ammonium bicarbonate liquid to a jet absorber, introducing gas ammonia for absorption, and obtaining two ammonium liquids. And simultaneously sending the decalcifying solution and the two ammonium solutions to a reaction tank for reaction. The ammonium bicarbonate concentration was 95 wt% and the ammonia purity was 99.99 wt%. The mass ratio of the first liquid to the ammonium bicarbonate and ammonia is 1:1: 0.2. The reaction temperature of the first liquid, the ammonium bicarbonate and the ammonia is 60 ℃, and the reaction time is 2 h.

Pumping the reacted slurry into a filter for secondary solid-liquid separation and washing to obtain second solid-liquid and second liquid (named as magnesium precipitation liquid).

And (3) scattering the second solid (in the form of a filter cake) by a scattering device, sending the second solid to a neutralization tank, adding water to prepare slurry, adding nitric acid to neutralize, and concentrating to obtain a magnesium nitrate product. The condensate produced by the concentration system is used for the filter press washing water.

Pumping the magnesium precipitation liquid after the second solid-liquid separation and water washing to a preheater (adopting condensate generated by medium-pressure steam as a heating medium), and preheating for 15s at 105 ℃. The preheated material enters a heat exchanger (the evaporated precipitated magnesium liquid is used as a heating medium), and is heated for 15s at the temperature of 120 ℃. Heating, evaporating in a forced circulation evaporator (making the temperature of the evaporated material liquid be 140 ℃), separating the evaporated material by a flash separator, concentrating in a granulating feeding trough, cooling the concentrated solution to 110 ℃ after heat exchange by a heat exchanger, then feeding to a granulator for granulation, cooling, screening and wrapping to obtain the magnesium potassium nitrate product. The condensate generated in the concentration process is used for washing water of the filter.

The calcium sulfate product obtained above had a CaO content of 39.42 wt%, and Mg (NO) in the magnesium nitrate₃)₂·6H₂The content of O is 98.63 wt%, and the potassium magnesium nitrate product contains N17.36wt% and K₂O21.65wt%, CaO0.62wt% and MgO2.62wt%.

Example 2

The embodiment provides a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, which comprises the following specific steps:

after being measured, the potassium sulfate is conveyed to a dissolving tank through a bucket elevator, and is conveyed to a decalcification tank after being stirred and dissolved. With P₂O₅The medium-low grade phosphorite with the content of 10-30 wt% is used as a raw material to prepare P through the working procedures of crushing, calcining, leaching, filter pressing separation and the like₂O₅Not less than 34.5 wt% and not more than 0.8 wt% of MgO5 wt% of low magnesium phosphate concentrate, the liquid discharged by the filter press in the process being used as the calcium and magnesium containing leachate.

Pumping the calcium-magnesium-containing leaching solution into a two-effect countercurrent evaporation device for concentration until the concentration of calcium magnesium ammonium nitrate is 32 wt%, and then pumping the concentrated calcium-magnesium-containing leaching solution into a decalcification tank for reaction with a potassium sulfate solution from a potassium sulfate dissolving tank. The concentration of the potassium sulfate solution used in the reaction is 35 wt%, and the mass ratio of the potassium sulfate solution to the calcium magnesium ammonium nitrate concentrated solution is 3: 5. The reaction temperature of the potassium sulfate solution and the concentrated solution of calcium magnesium ammonium nitrate is 20 ℃, and the reaction time is 6 hours.

And pumping the slurry after the decalcification reaction into a filter for first solid-liquid separation to obtain a first solid (in the form of a filter cake) and a first liquid (called decalcification liquid).

And (3) carrying out primary washing (primary washing) and secondary washing (secondary washing) on the first solid by using water, and drying and crushing the solid after the secondary washing to obtain a corresponding calcium sulfate product. Wherein, the washing liquid (first washing liquid) after the first washing is used for dissolving the potassium sulfate of the next batch, and the washing liquid (second washing liquid) after the second washing is used as the washing liquid for recycling in the first washing process of the next batch.

And (3) metering ammonium bicarbonate, then sending the ammonium bicarbonate to an ammonium bicarbonate dissolving tank for dissolving, pumping the ammonium bicarbonate liquid to a jet absorber, introducing gas ammonia for absorption, and obtaining two ammonium liquids. And simultaneously sending the decalcifying solution and the two ammonium solutions to a reaction tank for reaction. The ammonium bicarbonate concentration was 96 wt% and the ammonia purity was 99.99 wt%. The mass ratio of the first liquid to the ammonium bicarbonate and ammonia is 2:3: 1. The reaction temperature of the first liquid, the ammonium bicarbonate and the ammonia is 35 ℃, and the reaction time is 3 h.

Pumping the reacted slurry into a filter for secondary solid-liquid separation and washing to obtain second solid-liquid and second liquid (named as magnesium precipitation liquid).

And (3) scattering the second solid (in the form of a filter cake) by a scattering device, sending the second solid to a neutralization tank, adding water to prepare slurry, adding nitric acid to neutralize, and concentrating to obtain a magnesium nitrate product. The condensate produced by the concentration system is used for the filter press washing water.

Pumping the magnesium precipitation liquid after the second solid-liquid separation and water washing to a preheater (adopting condensate generated by medium-pressure steam as a heating medium), and preheating for 10s at the temperature of 110 ℃. The preheated material enters a heat exchanger (the evaporated precipitated magnesium liquid is used as a heating medium), and is heated for 10s at the temperature of 130 ℃. Heating, evaporating in a forced circulation evaporator (making the temperature of the evaporated material liquid be 150 ℃), separating the evaporated material by a flash separator, concentrating in a granulating feeding trough, cooling the concentrated solution to 100 ℃ after heat exchange by a heat exchanger, then feeding to a granulator for granulation, cooling, screening and wrapping to obtain the magnesium potassium nitrate product. The condensate generated in the concentration process is used for washing water of the filter.

The calcium sulfate product obtained above had a CaO content of 39.12 wt%, and Mg (NO) in the magnesium nitrate₃)₂·6H₂The content of O is 98.58 wt%, and the potassium magnesium nitrate product contains N19.78wt% and K₂O19.45wt%, CaO1.68wt% and MgO3.48wt%.

Example 3

The embodiment provides a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, which comprises the following specific steps:

after being measured, the potassium sulfate is conveyed to a dissolving tank through a bucket elevator, and is conveyed to a decalcification tank after being stirred and dissolved. With P₂O₅The medium-low grade phosphorite with the content of 10-30 wt% is used as a raw material to prepare P through the working procedures of crushing, calcining, leaching, filter pressing separation and the like₂O₅The low-magnesium phosphate concentrate with the weight percent of more than or equal to 34.5 percent and the weight percent of MgO less than or equal to 0.85 percent, and the liquid discharged by a filter press in the process is used as the leaching solution containing calcium and magnesium.

Pumping the calcium-magnesium-containing leaching solution into a two-effect countercurrent evaporation device for concentration until the concentration of calcium magnesium ammonium nitrate is 38 wt%, and then pumping the concentrated calcium-magnesium-containing leaching solution into a decalcification tank for reaction with a potassium sulfate solution from a potassium sulfate dissolving tank. The concentration of the potassium sulfate solution used in the reaction is 50 wt%, and the mass ratio of the potassium sulfate solution to the calcium magnesium ammonium nitrate concentrated solution is 5: 7. The reaction temperature of the potassium sulfate solution and the concentrated solution of calcium magnesium ammonium nitrate is 110 ℃, and the reaction time is 3 hours.

And pumping the slurry after the decalcification reaction into a filter for first solid-liquid separation to obtain a first solid (in the form of a filter cake) and a first liquid (called decalcification liquid).

And (3) carrying out primary washing (primary washing) and secondary washing (secondary washing) on the first solid by using water, and drying and crushing the solid after the secondary washing to obtain a corresponding calcium sulfate product. Wherein, the washing liquid (first washing liquid) after the first washing is used for dissolving the potassium sulfate of the next batch, and the washing liquid (second washing liquid) after the second washing is used as the washing liquid for recycling in the first washing process of the next batch.

And (3) metering ammonium bicarbonate, then sending the ammonium bicarbonate to an ammonium bicarbonate dissolving tank for dissolving, pumping the ammonium bicarbonate liquid to a jet absorber, introducing gas ammonia for absorption, and obtaining two ammonium liquids. And simultaneously sending the decalcifying solution and the two ammonium solutions to a reaction tank for reaction. The ammonium bicarbonate concentration was 99 wt% and the ammonia purity was 99.99 wt%. The mass ratio of the first liquid to the ammonium bicarbonate and ammonia was 4:5: 1.5. The reaction temperature of the first liquid, the ammonium bicarbonate and the ammonia is 80 ℃, and the reaction time is 1.5 h.

Pumping the reacted slurry into a filter for secondary solid-liquid separation and washing to obtain second solid-liquid and second liquid (named as magnesium precipitation liquid).

And (3) scattering the second solid (in the form of a filter cake) by a scattering device, sending the second solid to a neutralization tank, adding water to prepare slurry, adding nitric acid to neutralize, and concentrating to obtain a magnesium nitrate product. The condensate produced by the concentration system is used for the filter press washing water.

Pumping the magnesium precipitation liquid after the second solid-liquid separation and water washing to a preheater (adopting condensate generated by medium-pressure steam as a heating medium), and preheating for 5s at the temperature of 115 ℃. The preheated material enters a heat exchanger (the evaporated precipitated magnesium liquid is used as a heating medium), and is heated for 5s at the temperature of 140 ℃. Heating, evaporating in a forced circulation type evaporator (making the temperature of the evaporated material liquid be 165 ℃), separating the evaporated material by a flash separator, concentrating in a granulating feeding trough, cooling the concentrated solution to 120 ℃ after heat exchange by a heat exchanger, then sending to a granulator for granulation, cooling, screening and wrapping to obtain the magnesium potassium nitrate product. The condensate generated in the concentration process is used for washing water of the filter.

The obtained calcium sulfate product contains CaO in an amount of39.35 wt% of Mg (NO) in magnesium nitrate₃)₂·6H₂The content of O is 98.68 wt%, and the potassium magnesium nitrate product contains N19.26wt% and K₂O18.75wt%, CaO1.21wt% and MgO4.96wt%. .

Example 4

This example provides a method for preparing a calcium-containing product and a magnesium-containing product from a calcium-containing magnesium leaching solution, which is different from example 3 in that: and (3) only carrying out primary water washing on the first solid, and drying and crushing the solid after the primary water washing to obtain a corresponding calcium sulfate product.

To sum up, this application is through reacting calcium magnesium containing leachate with potassium sulphate solution in order to obtain calcium sulfate, further react first liquid after above-mentioned reaction separation with ammonium bicarbonate and ammonia, concentrate the granulation with reaction separation's second liquid in order to obtain potassium magnesium nitrate, react with nitric acid with the second solid after this reaction separation in order to obtain magnesium nitrate, thereby can carry out calcium magnesium separation with the calcium magnesium containing leachate of chemical ore dressing byproduct effectively, obtain substances such as calcium sulfate, potassium magnesium nitrate and magnesium nitrate simultaneously, improved the value of this kind of chemical ore dressing byproduct, enlarged the range of application of this kind of chemical ore dressing byproduct.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.