阅读说明：本技术 一种盐湖难过滤水氯镁石复合快速精制高浓度氯化镁溶液的方法 (Method for compounding and rapidly refining high-concentration magnesium chloride solution by using salt lake difficult-to-filter-water chloromagnesite ) 是由 白鹰 翁存建 徐徽 史政良 王生青 丁晓明 王洋 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种盐湖难过滤水氯镁石复合快速精制高浓度氯化镁溶液的方法,以按以下步骤进行,1)选用盐湖滩晒结晶的水氯镁石原料与清水放入溶解池中进行化卤搅拌,得到氯化镁粗溶液；2)加入复合剂氯化钙和硫酸镁进行搅拌获得复合氯化镁粗溶液,该溶液的pH值变化范围为6-8；3)将复合氯化镁粗溶液进行沉降,溢流液和滤液分别进行压滤,滤液即为精制高浓度氯化镁溶液。本发明通过在氯化镁粗溶液中添加复合剂,复合剂在溶液中发生化学反应,破坏了原有体系的架构,生成了CaSO-4·2H-2O晶体颗粒,在溶液中形成了桥架,絮凝了微细杂质胶体颗粒,同时在板框压滤机过滤过程中可在滤布上形成一层助滤层,能提升氯化镁粗溶液的过滤效率,进而提升产能。(The invention discloses a method for compounding and quickly refining a high-concentration magnesium chloride solution by using a salt lake difficult-to-filter bischofite, which comprises the following steps of 1) selecting a bischofite raw material and clear water which are subjected to solarization and crystallization in a salt lake beach, and putting the bischofite raw material and the clear water into a dissolving tank for carrying out halogen melting and stirring to obtain a magnesium chloride crude solution; 2) adding complexing agents of calcium chloride and magnesium sulfate, and stirring to obtain a crude composite magnesium chloride solution, wherein the pH value of the solution is changed within the range of 6-8; 3) and (3) settling the composite magnesium chloride crude solution, and respectively carrying out filter pressing on the overflow liquid and the filtrate to obtain the filtrate, namely the refined high-concentration magnesium chloride solution. According to the invention, the complexing agent is added into the magnesium chloride crude solution, and the complexing agent is subjected to chemical reaction in the solution, so that the framework of the original system is destroyed, and CaSO is generated 4 ·2H 2 The O crystal particles form a bridge frame in the solution, flocculate fine impurity colloid particles, and simultaneously can form a filter aid layer on the filter cloth in the filtering process of the plate and frame filter press, so that the filtering efficiency of the magnesium chloride crude solution can be improved, and the productivity is further improved.)

1. A method for quickly refining a high-concentration magnesium chloride solution by compounding salt lake refractory filter brucite is characterized by comprising the following steps: so as to carry out the following steps of,

1) halogenating raw material bischofite: selecting bischofite raw material and clean water which are subjected to sun crystallization by a salt lake beach according to the mass ratio of 2-3: 1, putting the bischofite raw material and the clean water into a dissolving pool for halogenating, stirring the bischofite raw material and the clean water in the halogenating pool, and slowly dissolving the bischofite into a magnesium chloride crude solution in a nearly saturated state;

2) adding a complexing agent: adding complexing agents of calcium chloride and magnesium sulfate into an output end of a magnesium chloride solution pool, and stirring to obtain a composite magnesium chloride crude solution, wherein the pH value change range of the solution is 6-8, the addition amount of the calcium chloride is 1-3g/L, and the addition amount of the magnesium sulfate is 1-3 g/L;

3) refining the high-concentration magnesium chloride solution: pumping the composite magnesium chloride crude solution obtained in the step 2) into a thickener for sedimentation, performing filter pressing on the overflow liquid by a first-stage plate-and-frame filter press, and performing filter pressing on the filtrate by a second-stage plate-and-frame filter press to obtain a filtrate, namely a refined high-concentration magnesium chloride solution, wherein Mg is used as the filtrate²⁺The content is 113 + -5 g/L.

2. The method for rapidly refining the high-concentration magnesium chloride solution by compounding the salt lake refractory drainage bischofite according to claim 1, which is characterized by comprising the following steps of: and adding a stirring device at the output end of the halogenating pool for stirring, wherein the stirring speed is 100-200 rpm, the stirring time is 10-30min, and the concentration of magnesium chloride in the obtained magnesium chloride crude solution is about 30-33%.

3. The method for rapidly refining the high-concentration magnesium chloride solution by compounding the salt lake refractory drainage bischofite according to claim 1, which is characterized by comprising the following steps of: the main components of the complexing agent in the step 2) are calcium chloride and magnesium sulfate, and the complexing agent comprises the following components in parts by mass: the calcium chloride content is 25% -75%, the magnesium sulfate content is 25% -75%, and the calcium chloride and the magnesium sulfate are mixed and stirred for 2 hours at normal temperature to prepare the calcium sulfate.

4. The method for rapidly refining the high-concentration magnesium chloride solution by compounding the salt lake refractory drainage bischofite according to claim 1, which is characterized by comprising the following steps of: the diameter of the thickener used in the step 3) is 9mThe physical ability is 0.2 m/h; the filtering area of the first-stage and second-stage plate-and-frame filter press is 125m²The mesh number of the filter cloth is 500 meshes, and the processing capacity is 4m³H; the filter area of the slurry plate-and-frame filter press is 125m²The mesh number of the filter cloth is 500 meshes, and the processing capacity is 2m³/h。

5. The method for rapidly refining the high-concentration magnesium chloride solution by compounding the salt lake refractory drainage bischofite according to claim 4, which is characterized by comprising the following steps of: after the high-concentration magnesium chloride solution is prepared in the step 3), the underflow of the thickener enters a slurry plate-and-frame filter press for filter pressing, the filtrate enters a one-step filter press for filter pressing, and filter cakes obtained by the first-stage and second-stage plate-and-frame filter presses and the slurry filter press are transported to a waste residue field by a special vehicle.

6. The method for rapidly refining the high-concentration magnesium chloride solution by compounding the salt lake refractory drainage bischofite according to claim 1, which is characterized by comprising the following steps of: the refined high-concentration magnesium chloride solution prepared in the step 3) is clear and transparent, and the Mg in the refined high-concentration magnesium chloride solution is²⁺The content was 113 g/L.

Technical Field

The invention relates to the technical field of chemical product preparation, in particular to a method for compositely refining a high-concentration magnesium chloride solution by filtering chloromagnesite difficultly in a salt lake.

Background

The Qinghai-province firewood wood basin is the most densely distributed area of salt lake resources in China, the storage capacity of inorganic salts reaches 3832 hundred million tons, and the potential value is very huge. The reserves of various resources of the Cherokee salt lake can reach more than 600 billion tons, wherein 5.4 billion tons of potassium chloride, 65 billion tons of bischofite, 1204 trillion tons of lithium chloride and 555 trillion tons of sodium chloride are contained, and meanwhile, rare elements such as boron, bromine, iodine, rubidium, cesium and the like are associated, and the potential economic value is close to 100 trillion yuan.

After the industrial development of the salt lake for more than 60 years, the Qinghai salt lake has developed into the largest base of potassium fertilizer and new energy materials in China, and the annual potassium chloride yield exceeds 500 ten thousand tons. However, since a development mode mainly for producing potassium fertilizer (extracting potassium chloride) is adopted for a long time, the effective utilization degree of other symbiotic and associated mineral resources is very low, wherein magnesium resources with huge reserves are always discharged as by-products and industrial tailings for potassium extraction, the utilization of magnesium resources in salt lakes is not sufficiently emphasized, the development technology is lagged behind, and the development of magnesium resources in salt lakes only stays at the stage of primary products or industrialized research and development. The method is characterized in that 8-10 tons of magnesium chloride are produced as a byproduct for each 1 ton of potassium chloride, the current annual production scale of potassium chloride in a Carman salt lake is about 500-700 million tons, the byproduct magnesium chloride is about 4500-8000 million tons, the magnesium chloride is sold as a primary product of magnesium chloride only about 30-50 million tons, a large amount of magnesium chloride is not effectively utilized, and the old brine after potassium extraction is basically discharged as waste liquid, so that not only is the resource greatly wasted, but also the resource occurrence structure is damaged, and the serious imbalance of resource development is caused.

Due to the change of properties of the bischofite raw material, although the content of magnesium chloride hexahydrate in the existing bischofite raw material reaches 96%, the impurity components are complex and the particle size of the impurity components is fine, the impurity components are suspended in the solution in a colloidal state after being dissolved and are difficult to filter, the capacity of refining high-concentration magnesium chloride solution is seriously reduced, the improvement of production capacity is restricted, the production cost is high, the efficient development of magnesium resources in salt lakes is not facilitated, and the development of magnesium industry is restricted. Therefore, the development of a method for compositely refining the high-concentration magnesium chloride solution by the attapulgite clay which is difficult to filter in the salt lake is urgent.

Disclosure of Invention

The invention aims to solve the technical problems of the prior art, provides a method for rapidly refining a high-concentration magnesium chloride solution by compounding difficult-to-filter bischofite in a salt lake by adding a complexing agent into a crude magnesium chloride solution to carry out a chemical reaction so as to improve the filtering efficiency of the crude magnesium chloride solution and further improve the filtering productivity of the refined high-concentration magnesium chloride solution, and aims to solve the problems of property change, difficult filtering and the like of the bischofite in the salt lake.

In order to solve the technical problems, the invention adopts the following technical scheme: a method for quickly refining a high-concentration magnesium chloride solution by compounding salt lake refractory filter brucite is characterized by comprising the following steps: so as to carry out the following steps of,

1) halogenating raw material bischofite: selecting bischofite raw material and clear water which are subjected to sun crystallization by using a salt lake beach according to the mass ratio of 2-3: 1 (such as 2.2: 1) to be placed into a dissolving tank for carrying out halogen dissolving, and stirring in a halogen dissolving tank to slowly dissolve the bischofite into a magnesium chloride crude solution in a nearly saturated state, wherein the concentration of magnesium chloride is 30-33%, such as 32.23%;

2) adding a complexing agent: adding complexing agents of calcium chloride and magnesium sulfate into an output end of a magnesium chloride solution pool, and stirring to obtain a composite magnesium chloride crude solution, wherein the pH value change range of the solution is 6-8, the addition amount of the calcium chloride is 1-3g/L, and the addition amount of the magnesium sulfate is 1-3 g/L;

3) refining the high-concentration magnesium chloride solution: pumping the composite magnesium chloride crude solution obtained in the step 2) into a thickener for sedimentation, and pressing a section of plate frame of overflow liquidFilter-pressing with a filter, and filter-pressing the filtrate with a two-stage plate-and-frame filter press to obtain refined high-concentration magnesium chloride solution (Mg)²⁺The content is 113 + -5 g/L.

And adding a stirring device at the output end of the halogen melting tank for stirring, wherein the stirring speed is 100-200 rpm, and the stirring time is 10-30 min.

The main components of the complexing agent in the step 2) are calcium chloride and magnesium sulfate, and the complexing agent comprises the following components in parts by mass: the calcium chloride content is 25% -75%, the magnesium sulfate content is 25% -75%, and the calcium chloride and the magnesium sulfate are mixed and stirred for 2 hours at normal temperature to prepare the calcium sulfate.

The diameter of the thickener used in the step 3) is 9m, and the sedimentation speed is 0.2 m/h; the filtering area of the first-stage and second-stage plate-and-frame filter press is 125m²The mesh number of the filter cloth is 500 meshes, and the processing capacity is 4m³H; the filter area of the slurry plate-and-frame filter press is 125m²The mesh number of the filter cloth is 500 meshes, and the processing capacity is 4m³/h。

After the high-concentration magnesium chloride solution is prepared in the step 3), the underflow of the thickener enters a slurry plate-and-frame filter press for filter pressing, the filtrate enters a one-step filter press for filter pressing, and filter cakes obtained by the first-stage and second-stage plate-and-frame filter presses and the slurry filter press are transported to a waste residue field by a special vehicle.

The refined high-concentration magnesium chloride solution prepared in the step 3) is clear and transparent, and the Mg in the refined high-concentration magnesium chloride solution is²⁺The content was 113 g/L.

According to the invention, the complexing agent is added into the magnesium chloride crude solution, and the complexing agent is subjected to chemical reaction in the solution, so that the framework of the original system is destroyed, and CaSO is generated₄·2H₂The O crystal particles form a bridge frame in the solution to flocculate fine impurity colloid particles, and meanwhile, a filter aid layer can be formed on the filter cloth in the filtering process of the plate-and-frame filter press, so that the filtering efficiency of the magnesium chloride crude solution is improved, and the filtering capacity of the over-refined high-concentration magnesium chloride solution is further improved.

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

1. according to the invention, the complexing agent is added into the magnesium chloride crude solution, so that the framework of the original solution system is changed, and the viscosity of the solution is reduced;

2. the added complexing agent is subjected to chemical reaction in a magnesium chloride crude solution to generate CaSO₄·2H₂The O crystal particles form a bridge frame in the solution to flocculate fine impurity colloid particles, and meanwhile, a filter aid layer can be formed on the filter cloth in the filtering process of the plate-and-frame filter press, so that the filtering efficiency of the magnesium chloride crude solution is improved, and the filtering capacity of the over-refined high-concentration magnesium chloride solution is further improved;

3. after the complexing agent is chemically reacted in the solution, insoluble CaSO is generated₄·2H₂O crystal particles are left in the filter cake after filter pressing, and the chemical quality index of a subsequent product cannot be influenced.

Drawings

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

Detailed Description

The invention is further illustrated by the following specific embodiments in conjunction with the accompanying drawings:

the method for quickly refining the high-concentration magnesium chloride solution by compounding the salt lake refractory filtered water chloromagnesite comprises the following steps:

1) halogenating raw material bischofite: selecting bischofite raw materials and clean water which are subjected to sun crystallization by a salt lake beach according to the mass ratio of 2.2: 1, putting the bischofite raw materials and the clean water into a dissolving pool for halogenating, adding a stirring device at the output end of the halogenating pool for stirring, wherein the stirring speed is 100-200 rpm, and the stirring time is 10-30min, and slowly dissolving the bischofite into a magnesium chloride crude solution in a nearly saturated state, wherein the concentration of the magnesium chloride crude solution is about 32.23%;

2) adding a complexing agent: adding complexing agents of calcium chloride and magnesium sulfate into the output end of the magnesium chloride solution pool, and stirring to obtain a composite magnesium chloride crude solution, wherein the change range of the pH value of the solution is 6-8; the adding amount of calcium chloride in the complexing agent is 1g/L (1-3g/L all), and the adding amount of magnesium sulfate is 1g/L (1-3g/L all);

3) refining the high-concentration magnesium chloride solution: and (3) pumping the composite magnesium chloride crude solution obtained in the step 2) into a thickener for sedimentation, performing filter pressing on the overflow liquid by using a first-stage plate-and-frame filter press, and performing filter pressing on the filtrate by using a second-stage plate-and-frame filter press to obtain the refined high-concentration magnesium chloride solution. The underflow of the thickener enters a slurry plate-and-frame filter press for filter pressing, the filtrate enters a one-step filter press for filter pressing, and filter cakes obtained by the first-stage and second-stage plate-and-frame filter presses and the slurry filter press are transported to a waste residue field by a special vehicle.

Wherein the diameter of the thickener is 9m, the sedimentation velocity is 0.2m/h, and the filtering area of the first-stage and second-stage plate-and-frame filter presses is 125m²The mesh number of the filter cloth is 500 meshes, and the processing capacity is 4m³The filter area of the slurry plate-and-frame filter press is 125m²The mesh number of the filter cloth is 500 meshes, and the processing capacity is 4m³/h。

The refined high-concentration magnesium chloride solution which is finally obtained is clear and transparent, and the Mg of the refined high-concentration magnesium chloride solution is²⁺The content was 113 g/L.

Secondly, carrying out chemical multi-element analysis on the bischofite raw material: MgCl₂·6H₂O content 96%, Ca²⁺Content 0.25%, SO₄ ²⁺0.08% of the total content, 0.12% of the content of water-insoluble substances, 0.61% of NaCl and 0.35% of KCl. The water insoluble substance in bischofite is mainly SiO₂And CaO, etc.

Preparing 200L of 32% magnesium chloride crude solution, adding complexing agent into the solution, wherein the calcium chloride content is 50g, the magnesium sulfate content is 100g, the stirring speed is controlled at 100rpm, and stirring for 10 min. After dense settling and plate-frame filtering, the content of each ion in the solution is analyzed, and Mg in the refined high-concentration magnesium chloride solution is calculated²⁺The content is 110g/L, Ca²⁺Content 0.05%, SO₄ ²⁺0.02% of Na and⁺+K⁺the content was 43ppm, and the solution was clear and transparent, the filtration time being 3 min.

And thirdly, carrying out chemical multi-element analysis on the bischofite raw material: MgCl₂·6H₂O content 97.1%, Ca²⁺Content of 0.16%, SO₄ ^{2 +}0.08% of the total content, 0.12% of the content of water-insoluble substances, 0.61% of NaCl and 0.35% of KCl. The water insoluble substance in bischofite is mainly SiO₂And CaO, etc.

Preparing 200L of 33% magnesium chloride crude solution, adding complexing agent into the solution, wherein calcium chloride contains additive amount100g of magnesium sulfate, 150g of magnesium sulfate, and 20min of stirring with a stirring speed of 200 rpm. After dense settling and plate-frame filtering, the content of each ion in the solution is analyzed, and Mg in the refined high-concentration magnesium chloride solution is calculated²⁺Content 114g/L, Ca²⁺Content of 0.04%, SO₄ ²⁺0.03% of Na⁺+K⁺Content 46ppm, and the solution was clear and transparent, and the filtration time was 3 min.

The traditional preparation process of high-concentration refined brine is consistent with the invention except that the complexing agent is not added, and under the condition that the indexes of the raw materials are the same as those of the raw materials of the second step (polychlorinated magnesite raw material chemical multi-element analysis) and the third step (polychlorinated magnesite raw material chemical multi-element analysis), 200L of 33% magnesium chloride crude solution is prepared, the complexing agent is added into the solution, wherein the adding amount of calcium chloride is 100g, the adding amount of magnesium sulfate is 150g, the stirring speed is controlled at 200rpm, and the stirring is carried out for 20 min. After dense settling and plate-frame filtering, the content of each ion in the solution is analyzed, and Mg in the refined high-concentration magnesium chloride solution is calculated²⁺The content is 110g/L to 114g/L, Ca²⁺0.04-0.05% of SO₄ ²⁺0.02-0.03% of Na⁺+K⁺The content is 43-46ppm, and the solution is clear and transparent, and the filtration time is 15 min.

Compared with the traditional high-concentration brine preparation process, the process disclosed by the invention has the advantages that on the premise of ensuring that the physicochemical indexes of the prepared high-concentration refined brine are basically unchanged, the filtering time can be reduced by 5 times, the filtering efficiency is improved, the limitation that the filtering capacity of industrial production is limited so as to influence the improvement of the magnesium series product capacity is solved, the equipment investment and the production cost are reduced, and the rapid filtering advantage of the chloromagnesite for difficult water filtration in salt lakes is remarkable.

The present invention has been described in detail, and it should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.