阅读说明：本技术 一种控制液体平衡的磷精矿制备系统 (Control liquid balance's phosphate concentrate preparation system ) 是由 张建军 黄德明 华建青 刘法安 于 2018-08-31 设计创作，主要内容包括：本发明提供了一种控制液体平衡的磷精矿制备系统,其中的碳化单元产生的固液混合物经过压滤单元进行压滤和洗涤,压滤单元对固液混合物进行压滤产生的滤液经过浓缩单元进行压滤浓缩,得到浓缩滤液,压滤单元对固液混合物进行洗涤产生的洗涤液经过浓缩单元进行洗涤浓缩,得到浓缩洗涤液；压滤浓缩和洗涤浓缩产生的水蒸气进行冷凝并经过冷凝水回收单元获得冷凝水；浓缩滤液用于磷矿浸取单元,浓缩洗涤液用于磷矿湿法球磨单元和/或磷矿浸取单元,冷凝水用于压滤单元。本发明提供的控制液体平衡的磷精矿制备系统将碳化单元产生的滤液在系统循环利用,可以实现系统中产生的液体在循环生产中保持平衡,减少废水产生。(The invention provides a phosphate concentrate preparation system for controlling liquid balance, wherein a solid-liquid mixture generated by a carbonization unit is subjected to filter pressing and washing by a filter pressing unit, a filtrate generated by the filter pressing of the solid-liquid mixture by the filter pressing unit is subjected to filter pressing and concentration by a concentration unit to obtain a concentrated filtrate, and a washing liquid generated by the washing of the solid-liquid mixture by the filter pressing unit is subjected to washing and concentration by the concentration unit to obtain a concentrated washing liquid; condensing water vapor generated by filter pressing concentration and washing concentration and obtaining condensed water through a condensed water recovery unit; the concentrated filtrate is used in a phosphorite leaching unit, the concentrated washing solution is used in a phosphorite wet ball milling unit and/or a phosphorite leaching unit, and the condensed water is used in a filter pressing unit. The phosphate concentrate preparation system for controlling liquid balance provided by the invention recycles the filtrate generated by the carbonization unit in the system, can realize the balance of the liquid generated in the system in the recycling production, and reduces the generation of wastewater.)

1. A phosphate concentrate preparation system for controlling liquid balance comprises a phosphate ore calcining unit, a phosphate ore wet ball milling unit, a phosphate ore leaching unit, a filter pressing unit, a carbonization unit, a concentration unit and a condensate water recovery unit; it is characterized in that the preparation method is characterized in that,

in the phosphate concentrate preparation system, after being calcined in the phosphate ore calcination unit, phosphate ore enters the phosphate ore wet ball milling unit to be subjected to wet ball milling to obtain phosphate ore slurry, the phosphate ore slurry is leached in the phosphate ore leaching unit to obtain a calcium-magnesium-containing solution and phosphate concentrate, and the calcium-magnesium-containing solution is carbonized in the carbonization unit to form a solid-liquid mixture containing calcium carbonate and magnesium carbonate;

the solid-liquid mixture generated by the carbonization unit is subjected to filter pressing and washing by the filter pressing unit, the filtrate generated by the filter pressing of the solid-liquid mixture by the filter pressing unit is subjected to filter pressing and concentration by the concentration unit to obtain concentrated filtrate, and the washing liquid generated by the washing of the solid-liquid mixture by the filter pressing unit is subjected to washing and concentration by the concentration unit to obtain concentrated washing liquid;

condensing the water vapor generated by the filter pressing concentration and the washing concentration and obtaining condensed water through the condensed water recovery unit;

the concentrated filtrate is used for the phosphorite leaching unit, the concentrated washing solution is used for the phosphorite wet ball milling unit and/or the phosphorite leaching unit, and the condensed water is used for the filter pressing unit.

2. The phosphate concentrate producing system according to claim 1, further comprising a gas treatment unit, wherein the phosphate ore leaching unit comprises a calcium ion leaching unit and a magnesium ion leaching unit, wherein ammonia gas and a leaching scrubbing solution are generated in the calcium ion leaching unit and the magnesium ion leaching unit, the leaching scrubbing solution being used in the phosphate ore wet ball milling unit, the ammonia gas being used in the gas treatment unit.

3. The phosphate concentrate producing system according to claim 2, wherein the calcium ion leaching unit is configured to add an ammonium ion solution having a first predetermined concentration to the phosphate ore slurry to leach calcium from the phosphate ore slurry to obtain a calcium ion-containing solution, and further comprising an ammonium ion replenishment unit, wherein the ammonia gas is further replenished to the calcium ion leaching unit through the ammonium ion replenishment unit, so that the calcium ion leaching unit has a first predetermined leaching efficiency.

4. The phosphate concentrate preparation system according to claim 3, wherein the carbonization unit includes a calcium ion carbonization unit, the calcium ion carbonization unit is configured to react the calcium ion-containing solution with an ammonium carbonate solution to generate a calcium carbonate and an ammonium ion solution, the solid-liquid mixture includes the calcium carbonate and the ammonium ion solution, and the filter-pressing unit performs filter-pressing concentration on the filtrate generated by filter-pressing the solid-liquid mixture by the filter-pressing unit through the concentration unit to obtain a concentrated filtrate, and the process includes:

the filter pressing unit is used for carrying out filter pressing on the solid-liquid mixture to generate filtrate, and the filtrate is subjected to filter pressing concentration through the concentration unit to obtain concentrated filtrate, wherein the concentrated filtrate is an ammonium ion solution with a first preset concentration;

the first predetermined concentration of ammonium ion solution is used in the calcium ion leach unit.

5. The phosphate concentrate producing system according to claim 3, wherein the magnesium ion leaching unit is configured to add an ammonium ion solution having a second predetermined concentration to the phosphate ore slurry to leach magnesium from the phosphate ore slurry to obtain a magnesium ion-containing solution, and the ammonia gas is further supplemented to the magnesium ion leaching unit by the ammonium ion replenishment unit to provide a second predetermined efficiency of magnesium ion leaching by the magnesium ion leaching unit.

6. The phosphate concentrate preparation system according to claim 5, wherein the carbonization unit further comprises a magnesium ion carbonization unit, the magnesium ion carbonization unit is configured to react the magnesium ion-containing solution with an ammonium carbonate solution to generate a magnesium carbonate and an ammonium ion solution, the solid-liquid mixture comprises the magnesium carbonate and the ammonium ion solution, and the step of performing filter-pressing concentration on the filtrate, which is generated by filter-pressing the solid-liquid mixture by the filter-pressing unit, by the concentration unit to obtain the concentrated filtrate comprises the steps of:

the filter pressing unit is used for carrying out filter pressing on the solid-liquid mixture to generate filtrate, and the filtrate is subjected to filter pressing concentration through the concentration unit to obtain concentrated filtrate, wherein the concentrated filtrate is an ammonium ion solution with a second preset concentration;

the second predetermined concentration of ammonium ion solution is used in the magnesium ion leach unit.

7. The phosphate concentrate preparation system according to claim 2, wherein the gas treatment unit comprises a cyclone separator, the phosphate ore calcining unit is communicated with the cyclone separator, dust generated by the phosphate ore calcining unit in the process of calcining phosphate ore enters the gas treatment unit, and solid generated by the cyclone separator in the process of calcining phosphate ore is added into the phosphate ore wet ball milling unit, the phosphate ore leaching unit or enters the phosphate ore calcining unit again.

8. The phosphate concentrate preparation system according to claim 7, wherein the solids produced by the cyclone are wetted with water before being re-introduced into the phosphate ore calcination unit.

9. The phosphate concentrate producing system according to claim 2, characterized in that the gas treatment unit further comprises a gas absorption plant, the ammonia gas produced by the phosphate leaching unit being used to form an ammonium carbonate solution through the gas absorption plant, the ammonium carbonate solution being used in the carbonation unit.

10. The phosphate concentrate producing system according to claim 9, wherein carbon dioxide gas produced by the phosphorite calcining unit calcining the phosphorite and ammonia gas produced by the phosphorite leaching unit pass through the gas absorption device to form an ammonium carbonate solution, and the ammonium carbonate solution is used in the carbonization unit.

Technical Field

The invention relates to the technical field of fertilizers, in particular to a phosphate concentrate preparation system for controlling liquid balance.

Background

Phosphorite is a non-renewable resource, although the phosphorite resource in China is relatively rich, the grade of the phosphorite is low, most of the phosphorite can be used for producing phosphoric acid, high-concentration phosphate fertilizer and the like only after being subjected to mineral separation and enrichment, and the actual utilization rate of the phosphorite in China is low due to more impurities in the phosphorite. In the process research of preparing phosphate concentrate from phosphate ore, more research methods are related to how to obtain phosphate concentrate with high purity. However, the process for preparing the phosphate concentrate involves a plurality of links, and each link can generate a large amount of waste water, waste gas and waste residues. Therefore, water balance in the preparation process of the phosphate concentrate is difficult, a large amount of wastewater is easily generated due to large yield of the phosphate concentrate preparation, internal circulation of production water in a preparation system needs to be established in order to avoid wastewater generation, and various types of wastewater and condensate water generated need to be ensured to be reused in order to achieve the internal circulation.

CN201710912095.8 discloses a circulating environment-friendly process method for preparing phosphate concentrate, which comprises the following steps: calcining the phosphorite raw material at 900-1100 ℃ to obtain calcined slag and pyrolysis waste gas; leaching the calcined slag with an ammonium ion solution to obtain ammonia gas and leaching slurry; carrying out solid-liquid separation on the leaching slurry to obtain phosphate concentrate and leaching solution; absorbing ammonia gas with an acid solution to obtain a first ammonium salt solution, and leaching the calcined slag by using the first ammonium salt solution as a raw material of an ammonium ion solution of the leaching reaction. The process discloses the reuse of the ammonia gas produced and does not involve equilibrium between liquid water.

CN201510226257.3 discloses a method for extracting phosphate concentrate from phosphate tailings and co-producing calcium ammonium nitrate and magnesium ammonium sulfate, which comprises the steps of calcining the phosphate tailings serving as a raw material at a high temperature, adding hot water into the calcined material for digestion treatment, then adding an ammonium nitrate solution for stirring, leaching calcium at a certain temperature to obtain a calcium-containing leaching solution and leaching residues, leaching magnesium from the leaching residues by using an ammonium sulfate solution to obtain the phosphate concentrate and the magnesium-containing leaching solution, concentrating and drying the calcium-containing leaching solution and the magnesium-containing leaching solution respectively to obtain calcium ammonium nitrate and magnesium ammonium sulfate, and recovering washing liquor generated in the calcium leaching process for digestion. The method only involves using the washing liquor generated in the calcium leaching process for digestion, but only utilizes a small part of the waste water generated in the whole system for preparing the phosphate concentrate, and the water balance of the whole system cannot be achieved.

Disclosure of Invention

In view of the above, the present invention provides a phosphate concentrate preparation system capable of controlling liquid balance. The specific technical scheme is as follows.

A phosphate concentrate preparation system for controlling liquid balance comprises a phosphate ore calcining unit, a phosphate ore wet ball milling unit, a phosphate ore leaching unit, a filter pressing unit, a carbonization unit, a concentration unit and a condensate water recovery unit;

in the phosphate concentrate preparation system, after being calcined in the phosphate ore calcination unit, phosphate ore enters the phosphate ore wet ball milling unit to be subjected to wet ball milling to obtain phosphate ore slurry, the phosphate ore slurry is leached in the phosphate ore leaching unit to obtain a calcium-magnesium-containing solution and phosphate concentrate, and the calcium-magnesium-containing solution is carbonized in the carbonization unit to form a solid-liquid mixture containing calcium carbonate and magnesium carbonate;

the solid-liquid mixture generated by the carbonization unit is subjected to filter pressing and washing by the filter pressing unit, the filtrate generated by the filter pressing of the solid-liquid mixture by the filter pressing unit is subjected to filter pressing and concentration by the concentration unit to obtain concentrated filtrate, and the washing liquid generated by the washing of the solid-liquid mixture by the filter pressing unit is subjected to washing and concentration by the concentration unit to obtain concentrated washing liquid;

condensing the water vapor generated by the filter pressing concentration and the washing concentration and obtaining condensed water through the condensed water recovery unit;

the concentrated filtrate is used for the phosphorite leaching unit, the concentrated washing solution is used for the phosphorite wet ball milling unit and/or the phosphorite leaching unit, and the condensed water is used for the filter pressing unit.

Preferably, the phosphate concentrate preparation system further comprises a gas treatment unit, the phosphate ore leaching unit comprises a calcium ion leaching unit and a magnesium ion leaching unit, ammonia gas and leaching washing liquid are generated in the calcium ion leaching unit and the magnesium ion leaching unit, the leaching washing liquid is used in the phosphate ore wet ball milling unit, and the ammonia gas is used in the gas treatment unit.

Preferably, the calcium ion leaching unit is used for adding an ammonium ion solution with a first preset concentration into the phosphorite slurry to leach calcium in the phosphorite slurry to obtain a calcium ion-containing solution, the phosphorite leaching unit further comprises an ammonium ion supplementing unit, and the ammonia gas is supplemented into the calcium ion leaching unit through the ammonium ion supplementing unit, so that the calcium ion leaching efficiency of the calcium ion leaching unit has a first preset efficiency.

Preferably, the carbonization unit includes a calcium ion carbonization unit, the calcium ion carbonization unit is configured to react the calcium-containing ionic solution with an ammonium carbonate solution to generate a calcium carbonate and an ammonium ionic solution, the solid-liquid mixture includes the calcium carbonate and the ammonium ionic solution, and the step of performing filter-pressing concentration on the filtrate generated by filter-pressing the solid-liquid mixture by the filter-pressing unit by the concentration unit to obtain the concentrated filtrate includes:

the filter pressing unit is used for carrying out filter pressing on the solid-liquid mixture to generate filtrate, and the filtrate is subjected to filter pressing concentration through the concentration unit to obtain concentrated filtrate, wherein the concentrated filtrate is an ammonium ion solution with a first preset concentration;

the first predetermined concentration of ammonium ion solution is used in the calcium ion leach unit.

Preferably, the magnesium ion leaching unit is used for adding an ammonium ion solution with a second preset concentration into the phosphorite slurry to leach magnesium in the phosphorite slurry to obtain a magnesium ion-containing solution, and the ammonia gas is supplemented into the magnesium ion leaching unit through the ammonium ion supplementing unit so that the efficiency of the magnesium ion leaching unit in leaching magnesium ions has a second preset efficiency.

Preferably, the carbonization unit includes a magnesium ion carbonization unit, the magnesium ion carbonization unit is configured to react the magnesium ion-containing solution with an ammonium carbonate solution to generate magnesium carbonate and an ammonium ion solution, the solid-liquid mixture includes the magnesium carbonate and the ammonium ion solution, and the step of performing filter-pressing concentration on the filtrate generated by filter-pressing the solid-liquid mixture by the filter-pressing unit by the concentration unit to obtain the concentrated filtrate includes:

the filter pressing unit is used for carrying out filter pressing on the solid-liquid mixture to generate filtrate, and the filtrate is subjected to filter pressing concentration through the concentration unit to obtain concentrated filtrate, wherein the concentrated filtrate is an ammonium ion solution with a second preset concentration;

the second predetermined concentration of ammonium ion solution is used in the magnesium ion leach unit.

Preferably, the gas treatment unit comprises a cyclone separator, the phosphorite calcining unit is communicated with the cyclone separator, dust generated by phosphorite calcining of the phosphorite calcining unit enters the gas treatment unit, and solid generated by separation of the cyclone separator is added into the phosphorite wet ball milling unit, the phosphorite leaching unit or enters the phosphorite calcining unit again.

Preferably, before the solid generated by the separation of the cyclone separator enters the phosphorite calcining unit again, the generated solid is wetted by adding water and then enters the phosphorite calcining unit.

Preferably, the gas treatment unit further comprises a gas absorption plant through which the ammonia gas produced by the phosphate rock leach unit is used to form an ammonium carbonate solution for use in the carbonisation unit.

Preferably, carbon dioxide gas generated by the phosphorite calcining unit in the process of calcining the phosphorite and ammonia gas generated by the phosphorite leaching unit pass through the gas absorption device to form ammonium carbonate solution, and the ammonium carbonate solution is used in the carbonization unit.

The invention has the beneficial effects that: the phosphate concentrate preparation system for controlling liquid balance provided by the invention recycles the filtrate generated by the carbonization unit in the system, can realize the balance of the liquid generated in the system in the recycling production, and reduces the generation of wastewater.

Drawings

Fig. 1 is a block diagram showing a system for preparing phosphate concentrate according to the present invention, which controls the liquid balance.

FIG. 2 is a block diagram of the phosphorite leaching unit.

Fig. 3 is a block diagram of the carbonization unit.

Fig. 4 is a block diagram of the gas processing unit.

Detailed Description

While the following is a description of the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Referring to fig. 1, the present invention provides a phosphate concentrate preparation system 10 with controlled liquid balance, the phosphate concentrate preparation system 10 includes a phosphate ore calcining unit 100, a phosphate ore wet ball milling unit 200, a phosphate ore leaching unit 300, a filter pressing unit 400, a carbonization unit 500, a concentration unit 600 and a condensate water recovery unit 700, in the phosphate concentrate preparation system 10, phosphate ore enters the phosphate ore wet ball milling unit 200 for wet ball milling after being calcined in the phosphate ore calcining unit 100 to obtain phosphate ore slurry, the phosphate ore slurry is leached in the phosphate ore leaching unit 300 to obtain a calcium and magnesium containing solution and phosphate concentrate, and the calcium and magnesium containing solution is carbonized in the carbonization unit 500 to form a solid-liquid mixture including calcium carbonate and magnesium carbonate.

It will be appreciated that phosphate ores include calcium carbonate, magnesium carbonate and phosphorus salts, typically dolomite (CaCO)₃·MgCO₃) Calcite (CaCO)₃) And fluorapatite (Ca)₅F(PO₄)₃) Exist in the form of (1). In the phosphorite calcining unit 100, calcium carbonate is calcined to produce calcium oxide and carbon dioxide, and magnesium carbonate is calcined to produce magnesium oxide and carbon dioxide. Oxygen gasThe calcium hydroxide and magnesium hydroxide solids are leached in the phosphate ore wet ball milling unit 200 to form calcium ions and magnesium ions, which are then formed into calcium carbonate and magnesium carbonate in the carbonation unit 500. Wherein the leaching reaction preferably occurs in the phosphorite leaching unit 300 using calcium hydroxide solids and magnesium hydroxide solids and an ammonium ion solution, preferably an ammonium nitrate solution.

The solid-liquid mixture generated by the carbonization unit 500 is subjected to filter pressing and washing by the filter pressing unit 400, and the filtrate generated by filter pressing of the solid-liquid mixture by the filter pressing unit 400 is subjected to filter pressing and concentration by the concentration unit 600 to obtain concentrated filtrate. Wherein the concentrated filtrate includes ammonium ions. The filter pressing unit 500 washes the solid-liquid mixture to generate a washing solution, and the washing solution is washed and concentrated by the concentration unit 600 to obtain a concentrated washing solution. Wherein the concentrated washing solution contains a small amount of ammonium ions.

The water vapor generated by the filter-pressing concentration and the washing concentration is condensed and passes through the condensed water recovery unit 700 to obtain condensed water. The resulting condensate is free of impurities, but does not exclude trace impurities with system equipment.

The concentrated filtrate is used in the phosphate ore leaching unit 300, the concentrated washing solution is used in the phosphate ore wet ball milling unit 200 and/or the phosphate ore leaching unit 300, and the condensed water is used in the filter pressing unit 400.

Calcium hydroxide and magnesium hydroxide need to be leached in the phosphorite leaching unit 300, ammonium ion concentrated filtrate with a large concentration needs to be subjected to leaching reaction, and the concentrated filtrate is added to the phosphorite leaching unit 300 to be subjected to leaching reaction, so that the concentrated filtrate generated in the carbonization unit 500 can be recycled, the liquid balance in the phosphate concentrate preparation system 10 is controlled, and the waste of liquid amount is reduced. The phosphorite wet ball milling unit 200 is required to add liquid into the phosphorite for ball milling, the generation of dust during the ball milling and the crushing of the phosphorite can be reduced by adopting the liquid for wet ball milling, the ball milling can be more uniform by adding the liquid, and the concentrated washing liquid can be added into the phosphorite wet ball milling unit 200 to further control the liquid balance in the phosphate concentrate preparation system 10. Washing with water of higher purity is required in the filter press unit 400, and thus condensed water can be used in the filter press unit 400. The carbonization unit 500 is the last processing unit in the overall phosphate concentrate preparation system 10, and thus a large amount of water is accumulated in the carbonization unit 500. With the above arrangement, the liquid (containing a large amount of water) in the carbonization unit 500 is concentrated, and the concentrated liquid and the condensed water are reused, so that the phosphate concentrate preparation system 10 of the present invention can achieve the balance of the liquid generated in the system in the circulation production, reduce the generation of wastewater, and in some embodiments, achieve no generation of wastewater.

Referring to fig. 1 and 2, in a further embodiment, the phosphate concentrate production system 10 further includes a gas treatment unit 800, the phosphate ore leaching unit 300 includes a calcium ion leaching unit 310 and a magnesium ion leaching unit 320, ammonia gas and a leach scrubbing solution are generated in the calcium ion leaching unit 310 and the magnesium ion leaching unit 320, and the leach scrubbing solution is used in the phosphate ore wet ball milling unit 200. It will be appreciated that the pH of the leach liquor is above a predetermined value, preferably above 7, so that the calcium or magnesium oxide is not dissolved. The ammonia gas is used in the gas processing unit 800. That is, ammonia gas is collected by the gas processing unit 800 or used in other processing units through the gas processing unit 800. In this embodiment, the liquid balance in the phosphate concentrate preparation system 10 can be further controlled and controlled to avoid wasting leaching liquor.

In a further embodiment, the calcium ion leaching unit 310 is configured to add an ammonium ion solution having a first predetermined concentration to the phosphate ore slurry to leach calcium from the phosphate ore slurry to obtain a calcium ion-containing solution, the phosphate ore leaching unit 300 further includes an ammonium ion replenishment unit 330, and the ammonia gas is further supplemented to the calcium ion leaching unit 310 through the ammonium ion replenishment unit 330, so that the calcium ion leaching unit 310 has a first predetermined leaching efficiency. The ammonia gas in the gas treatment unit 800 is supplemented into the calcium ion leaching unit 310 through the ammonium ion supplementing unit 330, so that the generated ammonia gas can be fully utilized, and the reaction rate of the calcium hydroxide and the ammonium ion solution in the calcium ion leaching unit 310 can be maintained to accelerate the calcium ion leaching efficiency, preferably to make the calcium ion leaching efficiency be the first preset efficiency. Wherein the first preset efficiency refers to the efficiency of leaching calcium ions, which is set according to the efficiency of producing phosphate concentrate by the system and can be adjusted according to actual conditions. It will be appreciated that the first predetermined concentration of ammonium ion solution may be a 30% mass concentration ammonium nitrate solution.

In a further embodiment, the carbonization unit 500 includes a calcium ion carbonization unit 510, the calcium ion carbonization unit 510 is configured to react the calcium ion-containing solution with an ammonium carbonate solution to generate a calcium carbonate and an ammonium ion solution, the solid-liquid mixture includes the calcium carbonate and the ammonium ion solution, and the "filter pressing unit 400 performs filter pressing and concentration on the filtrate generated by filter pressing the solid-liquid mixture by using the concentration unit 600 to obtain a concentrated filtrate" includes:

the filter pressing unit 400 is used for carrying out filter pressing concentration on the filtrate generated by filter pressing of the solid-liquid mixture through the concentration unit 600 to obtain concentrated filtrate, the concentrated filtrate is an ammonium ion solution with a first preset concentration, and the ammonium ion solution with the first preset concentration is used for the calcium ion leaching unit. That is, the filtrate from the filter press unit 400 is concentrated to the same concentration as the ammonium ion solution required in the calcium ion leach unit 310 to allow the calcium ion leach reaction to proceed smoothly when the concentrated filtrate is used in the calcium ion leach unit 310. That is, the efficiency of the process utilized by the calcium ion leach unit 310 in the system is not affected while controlling the liquor balance.

In a further embodiment, the magnesium ion leaching unit 320 is configured to add an ammonium ion solution having a second predetermined concentration to the phosphate ore slurry to leach magnesium from the phosphate ore slurry to obtain a magnesium ion-containing solution, and the ammonia gas is supplemented to the magnesium ion leaching unit 320 by the ammonium ion replenishment unit 330, such that the efficiency of the magnesium ion leaching unit 320 in leaching magnesium ions has a second predetermined efficiency. Similarly, the addition of ammonia to the magnesium ion leach unit 320 allows the generated ammonia to be fully utilized and the reaction rate of magnesium hydroxide with the ammonium ion solution in the magnesium ion leach unit 310 to be maintained to increase the efficiency of magnesium ion leaching, preferably to a second predetermined efficiency of magnesium ion leaching. Wherein the second preset efficiency is the efficiency of leaching magnesium ions, which is set according to the efficiency of producing phosphate concentrate by the system and can be adjusted according to actual conditions. It is understood that the second predetermined concentration of ammonium ion solution is 30% by mass concentration of ammonium nitrate solution. In other embodiments, the second predetermined concentration may be set according to actual processing requirements. Preferably, the first preset concentration is equal to the second preset concentration, so that the concentration process time of the concentration unit is saved, and the system process is simplified.

Referring to fig. 3, in a further embodiment, the carbonization unit 500 includes a magnesium ion carbonization unit 520, the magnesium ion carbonization unit 520 is configured to react the magnesium ion-containing solution with an ammonium carbonate solution to generate magnesium carbonate and an ammonium ion solution, the solid-liquid mixture includes the magnesium carbonate and the ammonium ion solution, and the "performing filter-pressing concentration on the filtrate, which is generated by filter-pressing the solid-liquid mixture by the filter-pressing unit 400, by the concentration unit 600 to obtain a concentrated filtrate" includes:

the filter pressing unit 400 is used for carrying out filter pressing concentration on the filtrate generated by filter pressing of the solid-liquid mixture through the concentration unit to obtain concentrated filtrate, the concentrated filtrate is an ammonium ion solution with a second preset concentration, and the ammonium ion solution with the second preset concentration is used for the magnesium ion leaching unit. That is, the filtrate from the filter press unit 400 is concentrated to the same concentration as the ammonium ion solution required in the magnesium ion leach unit 320, so that the calcium ion leach reaction can proceed smoothly when the concentrated filtrate is used in the magnesium ion leach unit 320. That is, the efficiency of the process utilized by the magnesium ion leach unit 320 in the system is not affected while controlling the liquor balance.

Referring to fig. 4, in a further embodiment, the gas treatment unit 800 includes a cyclone 810, the phosphorite calcining unit 100 is communicated with the cyclone 810, dust generated by phosphorite calcining of the phosphorite calcining unit enters the gas treatment unit 800, and solid generated by separation of the phosphorite from the cyclone 810 is added to the phosphorite wet ball milling unit 200, the phosphorite leaching unit 300 or enters the phosphorite calcining unit 100 again. The solid in the dust generated by the phosphorite calcination comprises phosphorite powder, so that the solid can be added into the treatment unit for further recycling, and the waste of phosphorite resources is avoided.

In a further embodiment, the solids produced by the separation in the cyclone 810 are wetted with water before being re-introduced into the phosphate ore calcination unit 100 and then introduced into the phosphate ore calcination unit 100. The solid particles in the dust are small, the temperature in the phosphorite calcining unit 100 is high, and the solid is wetted by adding water and then enters the phosphorite calcining unit 100, so that the problem that the solid is directly changed into dust floating in the air after being heated and cannot be reused can be avoided.

In a further embodiment, the gas treatment unit 800 further comprises a gas absorption plant 820, and the ammonia gas produced by the phosphate rock leaching unit 300 is used to form an ammonium carbonate solution via the gas absorption plant 820, which is used in the carbonation unit 500. The ammonium carbonate solution forms calcium carbonate and magnesium carbonate with calcium ions and magnesium ions, respectively, in the carbonization unit 500 to control the ammonia-ammonium ion solution balance in the phosphate concentrate preparation system 10, and reduce ammonia emission.

In a further embodiment, the carbon dioxide gas produced by the phosphorite calcination unit 100 calcining the phosphorite and the ammonia gas produced by the phosphorite leaching unit 300 are passed through the gas absorption plant 820 to form an ammonium carbonate solution, which is used in the carbonization unit 500. Further utilization of carbon dioxide gas and ammonia gas, while reducing exhaust emissions, has a significant impact on the material or liquid balance control of that system.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.