CN101736404A - Co-production method of calcium sulfate whisker and phosphoric acid - Google Patents

Abstract

The co-production method of calcium sulfate whiskers and phosphoric acid, the process steps are: (1) acidolyze the phosphate rock powder with hydrochloric acid with a mass concentration of 15-26% or with nitric acid with a mass concentration of 30-54%, and the slurry after the acidolysis Filtrate to obtain the acidolysis solution containing Ca ²⁺ ; (2) take the acidolysis solution containing Ca ²⁺ obtained in step (1) and mass concentration 20～90% sulfuric acid as raw material, and the consumption of sulfuric acid is: in the acidolysis solution 100% of the theoretical amount of sulfuric acid required for the complete reaction of Ca ²⁺ with sulfuric acid, the sulfuric acid is added to the acid hydrolysis solution containing Ca ²⁺ under stirring, and the reaction is carried out at normal pressure and 50-90°C. , the calcium sulfate whiskers are separated by filtration, and then the calcium sulfate whiskers are washed and dried; (3) the filtrate obtained by filtering in step (2) is subjected to countercurrent extraction, and the raffinate aqueous phase is phosphoric acid, which is separated during countercurrent extraction The hydrochloric acid or nitric acid obtained by back-extracting the extracted organic phase with soft water is used for the acid hydrolysis of phosphate rock powder.

Description

Coproduction of Calcium Sulfate Whiskers and Phosphoric Acid

technical field

The invention belongs to the technical field of manufacturing calcium sulfate whiskers and wet-process phosphoric acid, and relates to a method for simultaneously producing calcium sulfate whiskers and phosphoric acid.

Background technique

Calcium sulfate whisker is a new material with great development potential, which has excellent properties such as high strength, good toughness, high temperature resistance and corrosion resistance. According to the length and diameter of calcium sulfate whiskers, it can be divided into three categories: short whiskers, medium-long whiskers and long whiskers. Short whiskers generally have a diameter of 0.1-4 μm and a length of 5-300 μm, and are mainly used in industries such as rubber, plastics, coatings, and adhesives; medium and long whiskers, with a length of 0.3-3.0 mm, are mainly used in papermaking and papermaking. Products industry; the length of long whiskers is greater than 3.0mm, mainly used in industries with high fiber length requirements, such as heat preservation, health care, textiles, etc.

At present, the main production method of calcium sulfate whiskers is the hydrothermal method, but the hydrothermal method has the following problems: production at high temperature or high pressure, high energy consumption, and high requirements for equipment; raw materials contain many impurities, which need to be purified and removed. Complicated, high production cost; the prepared calcium sulfate whiskers cannot meet the requirements of high aspect ratio industries.

Chinese patent No. ZL 200410024348.0 discloses a method for producing gypsum whiskers in phosphoric acid. The method is to decompose phosphate rock with excess concentration of 30-40% phosphoric acid to obtain phosphoric acid leach solution, and then leach phosphoric acid The solution is added to a sulfuric acid solution with a concentration of 30-35% to produce gypsum whiskers. This method has following deficiencies: 1, in CaO-P ₂ O ₅ -H ₂ O system, the concentration of CaO≤5% (see " production and application of phosphate ", chief editor Chen Jiafu, Tan Guangxun, Chengdu University of Science and Technology Press, Figure 8-4 on page 116), and excess phosphoric acid when decomposing phosphate rock and gradually adding phosphoric acid leaching solution to 30-35% sulfuric acid solution will also reduce the concentration of Ca ²⁺ in the suspension, while Ca ²⁺ The content is too low, which is not conducive to the growth of whiskers, thereby affecting the morphology of calcium sulfate whiskers, and it is difficult to obtain whiskers with relatively large major diameters (the whiskers prepared by the method described in this patent have a length of 30-200 μm, which belongs to short whiskers. The scope of application is limited); 2, the concentration of phosphoric acid is high, although it can increase the decomposition rate of phosphate rock, it will also increase the tendency of HPO ₄ ^2- to replace SO ₄ ^2- in the lattice, and the viscosity of the solution will increase accordingly. It leads to the deterioration of crystallization conditions, and also increases the difficulty of subsequent filtration operations; 3. To achieve a high decomposition rate of phosphate rock, the amount of circulating phosphoric acid is large, which requires pumps to transport, increases power consumption, and requires larger reactors , Increase equipment investment, which also increases production costs.

The Chinese patent No. ZL 200710065806.9 discloses a method for preparing calcium sulfate whiskers and phosphoric acid. The method includes decomposition of phosphate rock, slurry filtration and separation, preparation and separation of calcium sulfate whiskers, washing, and drying processes. Phosphoric acid with _{a P2O5} concentration of 18 to 35% and composite additive A (composite additive A is composed of humic acid and diatomite) are added during the ore decomposition process, and composite additive B (composite additive B consists of sodium lauryl sulfonate and sulfate or phosphate containing magnesium and aluminum). Although the addition of composite additive A can increase the decomposition rate of phosphate rock, and the addition of composite additive B can adjust the crystal form of calcium sulfate whiskers, the decomposition of phosphate rock is still CaO-P ₂ O ₅ -H ₂ O system, ZL 200410024348.0 patent Existing problems cannot be solved fundamentally. The influence of compound additive B on the crystallization of calcium sulfate is multifaceted, and the composition of the reaction solution is different, and the amount of additive to be added is also different. Generally, the optimal amount needs to be determined through experiments. Phosphoric acid leaching solution also contains impurities such as Mg ²⁺ , Al ³⁺ , Fe ²⁺ , etc. The presence of these impurities also affects the amount of additives used, so it is difficult to control the amount of additives used. Difficulty with whisker shape and size. ZL 200710065806.9 does not disclose the shape and size of the prepared calcium sulfate whiskers, so the application effect of the additive cannot be tested. In addition, the addition of additives increases costs and complicates the process.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, provide a kind of coproduction method of calcium sulfate whisker and phosphoric acid, this kind method can not only improve the ^{concentration} of Ca in the acidolysis solution, obtain different types of calcium sulfate whisker And phosphoric acid, and the process is simple, environmental protection and energy saving.

The technical scheme of the present invention: decompose phosphate rock with hydrochloric acid or nitric acid to obtain Ca2 ⁺ -containing acid solution, and then add sulfuric acid with a mass concentration of 20-90% to the Ca2 ⁺ -containing acid solution to produce phosphoric acid and calcium sulfate whiskers.

The present invention meets the following chemical reaction principle

Ca ₁₀ (PO ₄ ) ₆ F ₂ +20HCl→10CaCl ₂ +6H ₃ PO ₄ +2HF↑

Ca ₁₀ (PO ₄ ) ₆ F ₂ +20HNO ₃ →10Ca(NO ₃ ) ₂ +6H ₃ PO ₄ +2HF↑

The coproduction method of calcium sulfate whisker of the present invention and phosphoric acid, processing step is as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with hydrochloric acid with a mass concentration of 15-26% or with nitric acid with a mass concentration of 30-54%. Or 100% to 130% of the theoretical amount of nitric acid, the slurry after acidolysis of phosphate rock powder is filtered to obtain an acidolysis solution containing Ca ²⁺ ;

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution containing Ca2 ⁺ obtained in step (1) and mass concentration 20～90% sulfuric acid as raw materials, ^the consumption of sulfuric acid is: the required sulfuric acid theoretical amount when Ca in the acidolysis solution reacts completely with sulfuric acid 100%, adding the sulfuric acid into the Ca2 ⁺ -containing acidolysis solution under stirring, and reacting at normal pressure at 50-90°C, and the hydrochloric acid vapor or nitric acid vapor volatilized in the reaction process is cooled and refluxed with cooling water to In the reaction slurry (the cooling water is tap water or industrial water, and its temperature is room temperature or lower than room temperature), the reaction time is at least 1.5 hours. After the reaction finishes, the calcium sulfate crystal whiskers are separated by filtration, and then the obtained sulfuric acid Calcium whiskers are washed and dried;

(3) Preparation of phosphoric acid

The filtrate obtained by filtering in step (2) is subjected to countercurrent extraction, the raffinate aqueous phase is phosphoric acid, the volume ratio of the filtrate to the extractant is 1:1 to 5:1, the extraction temperature is 20 to 60°C, and the extraction residence time is 5 ~60 minutes.

When the filtrate is subjected to countercurrent extraction, the extracted organic phase is subjected to countercurrent back extraction with soft water to obtain hydrochloric acid or nitric acid, and the obtained hydrochloric acid or nitric acid is used for acidolysis of phosphate rock powder to form an environment-friendly and resource-efficient environment. The technological process, during back extraction, the volume ratio of the extracted organic phase to soft water = 0.5:1 to 5:1, the back extraction temperature is 20 to 60°C, and the washing residence time is 5 to 60 minutes.

In the above method, the phosphate rock powder can be medium and low-grade phosphate rock powder with a particle size ≤ 1165 μm.

In the above-mentioned method, preferred following process operation and process parameter:

1. When the phosphate rock powder is acid-hydrolyzed with hydrochloric acid with a mass concentration of 15-26%, the hydrochloric acid is first added to the reaction vessel, and then the phosphate rock powder is added to the hydrochloric acid under stirring, and the acid hydrolysis reaction is carried out under stirring. At normal pressure and room temperature, the time is at least 0.5 hours; when the phosphate rock powder is acidified with nitric acid with a mass concentration of 30-54%, the nitric acid is first added to the reaction vessel, and then the phosphate rock is added to the nitric acid under stirring Powder, the acid hydrolysis reaction is carried out under normal pressure at 30-50°C with stirring, and the time is at least 0.5 hours.

2. The calcium sulfate whiskers are washed with distilled water and technical alcohol successively, and the number of washings is at least 2 times.

3. When the filtrate obtained by filtering in step (2) is subjected to countercurrent extraction, the extractant is composed of trioctylamine and n-octanol, and the volume ratio of trioctylamine and n-octanol=2:1˜5:1.

Room temperature in the method of the present invention refers to indoor natural temperature.

The present invention has the following beneficial effects:

1. Because the method of the present invention uses the hydrochloric acid of 15～26% mass concentration or the nitric acid acid hydrolysis of mass concentration 30～54% of phosphate rock powder, thereby improved the content of ^Ca in the acidolysis solution, is the whisker growth Favorable conditions are provided.

2. By adopting the method of the present invention, calcium sulfate whiskers of different types (or specifications) can be obtained, which is conducive to expanding the application range of calcium sulfate whiskers.

3. Because hydrochloric acid hydrolysis of phosphate rock powder is carried out at normal pressure and room temperature, and nitric acid acid hydrolysis of phosphate rock powder is carried out at normal pressure and at 30-50°C, which is beneficial to energy saving.

4. The method of the present invention can realize no pollutant discharge and improve resource utilization rate, and is an environment-friendly and energy-saving process.

5. The method of the present invention can not only obtain phosphoric acid, but also obtain calcium sulfate whiskers of different types (or specifications), which has obvious economic and social benefits.

Description of drawings

Fig. 1 is the process flow sheet of the coproduction method of calcium sulfate whisker and phosphoric acid of the present invention;

Fig. 2 is the topography figure of the calcium sulfate whisker prepared by embodiment 1 under an electron microscope;

Fig. 3 is the topography figure of the calcium sulfate whisker prepared by embodiment 4 under an electron microscope;

Fig. 4 is the topography figure of the calcium sulfate whisker prepared in embodiment 7 under an electron microscope.

Detailed ways

The co-production method of calcium sulfate whiskers and phosphoric acid of the present invention will be further illustrated below by way of examples. In the following examples, the reaction vessels used in the calcium sulfate whisker preparation step are all containers with a stirring device and at least two ports. The grade of the raw phosphate rock is shown in Table 1, and the particle size of the phosphate rock powder is ≤ 1165 μm.

Table 1: Grade of Phosphate Rock

P ₂ O ₅ CaO _{Fe2O3 _} MgO Al ₂ O ₃ Cl acid insoluble matter 23.5～24% 46～47% 0.9～1.3% 0.3～0.7% 0.3～0.6% 0.6～2% 14～16%

Note: In Table 1, the percentages are mass percentages

Example 1

The processing steps of the present embodiment are as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with hydrochloric acid (prepared by analytical pure hydrochloric acid) with a mass concentration of 15%. The content of CaO in the phosphate rock powder is calculated as 46%. 130% of the theoretical amount; at first the hydrochloric acid is added to the reaction vessel, then rock phosphate powder is added to the hydrochloric acid under stirring, and the acid hydrolysis reaction is carried out at normal pressure and room temperature (26° C.) under stirring, and the time is 2 hours , after the reaction finishes, the reaction slurry is left standstill to layering, then obtains the acidolysis solution containing ^Ca through suction filtration, gets the acidolysis solution to detect, and records that the content of ^Ca in the acidolysis solution is 5.70% (mass percentage).

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution that contains Ca ²⁺ obtained in step (1) and the sulfuric acid of mass concentration 20% as raw material, the consumption of sulfuric acid is: ^Ca in the acidolysis solution 100 of the theoretical amount of sulfuric acid required when fully reacting with sulfuric acid %; the acid hydrolysis solution containing Ca2 ⁺ prepared by step (1) is added to the reaction vessel, then under stirring, sulfuric acid is added through an opening of the reaction vessel, and the condenser is connected through another opening of the reaction vessel to condense The temperature outside the tube is tap water at room temperature (26°C) to cool and reflux the hydrochloric acid vapor volatilized in the reaction process into the reaction slurry, the stirring speed is 250r/min, the reaction temperature is 50°C, and the reaction time is 1.5 hours; The calcium sulfate whiskers were separated by filtration, and the separated calcium sulfate whiskers were washed twice with distilled water and industrial alcohol twice, and then dried at 80°C for 60 minutes to remove surface moisture, and the obtained whiskers were in the shape of white needles , 20-40 μm long and 2-5 μm in diameter, its morphology under electron microscope is shown in Figure 2.

(3) Preparation of phosphoric acid

Filter the obtained filtrate in step (2) to carry out 5-stage countercurrent extraction, the extractant is made up of trioctylamine and n-octanol, the volume ratio of trioctylamine and n-octanol=2:1, the ratio of the filtrate to the extractant Volume ratio=1:1, extraction temperature 20°C, extraction residence time 5 minutes, the raffinate water phase is phosphoric acid (concentration or post-treatment such as impurity removal can be carried out as required); the extracted organic phase separated by countercurrent extraction is carried out with soft water for 5 minutes. Stage countercurrent back extraction, the volume ratio of the extracted organic phase to soft water = 0.5:1, the back extraction temperature is 20°C, the washing residence time is 5 minutes, and the hydrochloric acid obtained by the back extraction is used for the acid hydrolysis of the phosphate rock powder.

Example 2

The processing steps of the present embodiment are as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with hydrochloric acid (prepared by analytical pure hydrochloric acid) with a mass concentration of 21%. The content of CaO in the phosphate rock powder is calculated as 46%. 110% of the theoretical amount; at first the hydrochloric acid is added to the reaction vessel, then rock phosphate powder is added to the hydrochloric acid under stirring, and the acidolysis reaction is carried out at normal pressure and room temperature (28° C.) under stirring, and the time is 1 hour , after the reaction finishes, the reaction slurry is left standstill to layering, then obtains the acidolysis solution containing ^Ca through suction filtration, gets the acidolysis solution to detect, and records that the content of ^Ca in the acidolysis solution is 7.83% (mass percentage).

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution that contains Ca2 ⁺ obtained in step (1) and the sulfuric acid of mass concentration 50% as raw material, the consumption of sulfuric acid is: ^Ca in the acidolysis solution 100 of required sulfuric acid theoretical quantity when fully reacting with sulfuric acid %; the acid hydrolysis solution containing Ca2 ⁺ prepared by step (1) is added to the reaction vessel, then under stirring, sulfuric acid is added through an opening of the reaction vessel, and the condenser is connected through another opening of the reaction vessel to condense The temperature outside the tube is tap water at room temperature (28°C) to cool and reflux the hydrochloric acid vapor volatilized in the reaction process into the reaction slurry, the stirring speed is 300r/min, the reaction temperature is 60°C, and the reaction time is 2 hours; The calcium sulfate whiskers were separated by filtration, and the separated calcium sulfate whiskers were washed three times with distilled water and three times with industrial alcohol, and then dried at 80°C for 60 minutes to remove surface moisture. The obtained whiskers were in the shape of white needles , Observing calcium sulfate whiskers under an electron microscope: 150-300 μm long and 5-10 μm in diameter.

(3) Preparation of phosphoric acid

The filtrate obtained by filtering in step (2) is subjected to 3-stage countercurrent extraction, the extractant is composed of trioctylamine and n-octanol, the volume ratio of trioctylamine and n-octanol=3:1, the ratio of the filtrate to the extractant Volume ratio=3:1, extraction temperature 40°C, extraction residence time 20 minutes, the raffinate aqueous phase is phosphoric acid (concentration or post-treatment such as impurity removal can be carried out as required); the extracted organic phase separated by countercurrent extraction is carried out with soft water for 3 Stage countercurrent back extraction, the volume ratio of the extracted organic phase to soft water = 3:1, the back extraction temperature is 30°C, the washing residence time is 20 minutes, and the hydrochloric acid obtained from the back extraction is used for the acid hydrolysis of the phosphate rock powder.

Example 3

The processing steps of the present embodiment are as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with hydrochloric acid (prepared by analytical pure hydrochloric acid) with a mass concentration of 26%. The content of CaO in the phosphate rock powder is calculated as 46%. 100% of the theoretical amount; first the hydrochloric acid is added to the reaction vessel, then rock phosphate powder is added to the hydrochloric acid under stirring, and the acid hydrolysis reaction is carried out at normal pressure and room temperature (26° C.) under stirring, and the time is 0.5 hours , after the reaction finishes, the reaction slurry is left standstill to layering, then obtains the acidolysis solution containing ^Ca through suction filtration, gets the acidolysis solution to detect, and records that the content of ^Ca in the acidolysis solution is 8.98% (mass percentage).

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution that contains Ca2 ⁺ obtained in step (1) and the sulfuric acid of mass concentration 90% as raw material, the consumption of sulfuric acid is: ^Ca in the acidolysis solution When fully reacting with sulfuric acid, 100% of the theoretical amount of sulfuric acid required %; the acid hydrolysis solution containing Ca2 ⁺ prepared by step (1) is added to the reaction vessel, then under stirring, sulfuric acid is added through an opening of the reaction vessel, and the condenser is connected through another opening of the reaction vessel to condense The temperature outside the tube is tap water at room temperature (26°C) to cool and reflux the hydrochloric acid vapor volatilized in the reaction process into the reaction slurry, the stirring speed is 300r/min, the reaction temperature is 90°C, and the reaction time is 2 hours; The calcium sulfate whiskers were separated by filtration, and the separated calcium sulfate whiskers were washed with distilled water for 4 times and denatured alcohol for 4 times, and then dried at 80°C for 60 minutes to remove surface moisture. The obtained whiskers were in the shape of white needles , Observing calcium sulfate whiskers under an electron microscope: 40-100 μm long and 2-5 μm in diameter.

(3) Preparation of phosphoric acid

The filtrate obtained by filtering in step (2) is subjected to 2-stage countercurrent extraction, the extractant is composed of trioctylamine and n-octanol, the volume ratio of trioctylamine and n-octanol=5:1, the ratio of the filtrate to the extractant Volume ratio=5:1, extraction temperature 60°C, extraction residence time 60 minutes, raffinate aqueous phase is phosphoric acid (post-treatment such as concentration or impurity removal can be carried out as required); the extracted organic phase separated by countercurrent extraction is carried out with soft water for 2 Stage countercurrent back extraction, the volume ratio of the extracted organic phase to soft water = 5:1, the back extraction temperature is 60°C, the washing residence time is 60 minutes, and the hydrochloric acid obtained by the back extraction is used for the acid hydrolysis of the phosphate rock powder.

Example 4

The processing steps of the present embodiment are as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with hydrochloric acid (prepared by analytical pure hydrochloric acid) with a mass concentration of 26%. The content of CaO in the phosphate rock powder is calculated as 46%. 100% of the theoretical amount; at first the hydrochloric acid is added to the reaction vessel, then rock phosphate powder is added to the hydrochloric acid under stirring, and the acid hydrolysis reaction is carried out at normal pressure and room temperature (26° C.) under stirring, and the time is 3 hours , after the reaction finishes, the reaction slurry is left standstill to layering, then obtains the acidolysis solution containing ^Ca through suction filtration, gets the acidolysis solution to detect, and records that the content of ^Ca in the acidolysis solution is 9.23% (mass percentage).

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution that contains Ca2 ⁺ obtained in step (1) and the sulfuric acid of mass concentration 90% as raw material, the consumption of sulfuric acid is: ^Ca in the acidolysis solution When fully reacting with sulfuric acid, 100% of the theoretical amount of sulfuric acid required %; the acid hydrolysis solution containing Ca2 ⁺ prepared by step (1) is added to the reaction vessel, then under stirring, sulfuric acid is added through an opening of the reaction vessel, and the condenser is connected through another opening of the reaction vessel to condense The temperature outside the pipe is tap water at room temperature (26°C) to cool and reflux the hydrochloric acid vapor volatilized in the reaction process into the reaction slurry, the stirring speed is 250r/min, the reaction temperature is 60°C, and the reaction time is 2.5 hours; The calcium sulfate whiskers were separated by filtration, and the separated calcium sulfate whiskers were washed three times with distilled water and three times with industrial alcohol, and then dried at 80°C for 60 minutes to remove surface moisture. The obtained whiskers were in the shape of white needles , 600-1000 μm long, 10-20 μm in diameter, its morphology under electron microscope is shown in Figure 3.

(3) Preparation of phosphoric acid

The filtrate obtained by filtering in step (2) is subjected to 3-stage countercurrent extraction, the extractant is composed of trioctylamine and n-octanol, the volume ratio of trioctylamine and n-octanol=3:1, the ratio of the filtrate to the extractant Volume ratio=3:1, extraction temperature 30°C, extraction residence time 30 minutes, the raffinate aqueous phase is phosphoric acid (concentration or post-treatment such as impurity removal can be carried out as required); the extracted organic phase separated by countercurrent extraction is carried out with soft water for 3 Step countercurrent back extraction, the volume ratio of the extracted organic phase to soft water = 2:1, the back extraction temperature is 30°C, the washing residence time is 30 minutes, and the hydrochloric acid obtained by the back extraction is used for the acid hydrolysis of the phosphate rock powder.

Example 5

The processing steps of the present embodiment are as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with nitric acid (prepared by analytical pure nitric acid) with a mass concentration of 30%. The content of CaO in the phosphate rock powder is calculated as 46%. 130% of the theoretical amount; first, the nitric acid is added to the reaction vessel, then rock phosphate powder is added to the nitric acid under stirring, the acid hydrolysis reaction is carried out at normal pressure and 50°C under stirring, and the time is 1 hour, and the reaction ends Afterwards, the reaction slurry was allowed to stand until stratified, and then the acid hydrolysis solution containing Ca was obtained by suction filtration, and the acid hydrolysis solution was taken for detection, and the content of ^Ca in the acid hydrolysis solution was found to be 6.42% (mass percentage ⁾ .

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution that contains Ca ²⁺ obtained in step (1) and the sulfuric acid of mass concentration 20% as raw material, the consumption of sulfuric acid is: ^Ca in the acidolysis solution 100 of the theoretical amount of sulfuric acid required when fully reacting with sulfuric acid %; the acid hydrolysis solution containing Ca2 ⁺ prepared by step (1) is added to the reaction vessel, then under stirring, sulfuric acid is added through an opening of the reaction vessel, and the condenser is connected through another opening of the reaction vessel to condense The temperature of the pipe outside the pipe is tap water at room temperature (26°C), and the nitric acid vapor volatilized in the reaction process is cooled and refluxed in the reaction slurry, the stirring speed is 250r/min, the reaction temperature is 50°C, and the reaction time is 2.5 hours; The calcium sulfate whiskers were separated by filtration, and the separated calcium sulfate whiskers were washed twice with distilled water and industrial alcohol twice, and then dried at 80°C for 60 minutes to remove surface moisture, and the obtained whiskers were in the shape of white needles , Observing calcium sulfate whiskers under an electron microscope: 30-50 μm long and 5-10 μm in diameter.

(3) Preparation of phosphoric acid

Filter the obtained filtrate in step (2) to carry out 5-stage countercurrent extraction, the extractant is made up of trioctylamine and n-octanol, the volume ratio of trioctylamine and n-octanol=2:1, the ratio of the filtrate to the extractant Volume ratio=1:1, extraction temperature 20°C, extraction residence time 5 minutes, the raffinate water phase is phosphoric acid (concentration or post-treatment such as impurity removal can be carried out as required); the extracted organic phase separated by countercurrent extraction is carried out with soft water for 5 minutes. Stage countercurrent back extraction, the volume ratio of the extracted organic phase to soft water = 0.5:1, the back extraction temperature is 20°C, the washing residence time is 5 minutes, and the nitric acid obtained by the back extraction is used for the acid hydrolysis of the phosphate rock powder.

Example 6

The processing steps of the present embodiment are as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with nitric acid (prepared by analytical pure nitric acid) with a mass concentration of 40%. The content of CaO in the phosphate rock powder is calculated as 46%. 110% of the theoretical amount; first, the nitric acid is added to the reaction vessel, then rock phosphate powder is added to the nitric acid under stirring, the acid hydrolysis reaction is carried out at normal pressure and 40°C under stirring, and the time is 0.5 hours, and the reaction ends Afterwards, the reaction slurry was allowed to stand until stratified, and then the acid hydrolyzed solution containing Ca was obtained by suction filtration, and the acid hydrolyzed solution was taken for detection, and the content of ^Ca in the acid hydrolyzed solution was found to be 9.87% ⁽ mass percentage).

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution that contains Ca2 ⁺ obtained in step (1) and the sulfuric acid of mass concentration 50% as raw material, the consumption of sulfuric acid is: ^Ca in the acidolysis solution 100 of required sulfuric acid theoretical quantity when fully reacting with sulfuric acid %; the acid hydrolysis solution containing Ca2 ⁺ prepared by step (1) is added to the reaction vessel, then under stirring, sulfuric acid is added through an opening of the reaction vessel, and the condenser is connected through another opening of the reaction vessel to condense The temperature outside the tube is tap water at room temperature (26°C) to cool and reflux the nitric acid vapor volatilized in the reaction process into the reaction slurry, the stirring speed is 250r/min, the reaction temperature is 90°C, and the reaction time is 2.5 hours; The calcium sulfate whiskers were separated by filtration, and the separated calcium sulfate whiskers were washed three times with distilled water and three times with industrial alcohol, and then dried at 80°C for 60 minutes to remove surface moisture. The obtained whiskers were in the shape of white needles , Observing calcium sulfate whiskers under an electron microscope: 50-120 μm long and 2-5 μm in diameter.

(3) Preparation of phosphoric acid

The filtrate obtained by filtering in step (2) is subjected to 3-stage countercurrent extraction, the extractant is composed of trioctylamine and n-octanol, the volume ratio of trioctylamine and n-octanol=3:1, the ratio of the filtrate to the extractant Volume ratio=3:1, extraction temperature 40°C, extraction residence time 20 minutes, the raffinate aqueous phase is phosphoric acid (concentration or post-treatment such as impurity removal can be carried out as required); the extracted organic phase separated by countercurrent extraction is carried out with soft water for 3 Stage countercurrent back extraction, the volume ratio of the extracted organic phase to soft water = 3:1, the back extraction temperature is 30°C, the washing residence time is 20 minutes, and the nitric acid obtained by the back extraction is used for the acid hydrolysis of the phosphate rock powder.

Example 7

The processing steps of the present embodiment are as follows:

(1) Acid hydrolysis of phosphate rock powder

The phosphate rock powder is acidolyzed with nitric acid (prepared by analytical pure nitric acid) with a mass concentration of 54%. The content of CaO in the phosphate rock powder is calculated as 46%. 100% of the theoretical amount; first, the nitric acid is added to the reaction vessel, and then rock phosphate powder is added to the nitric acid under stirring, and the acid hydrolysis reaction is carried out at normal pressure and 50°C under stirring, and the time is 0.5 hours, and the reaction ends Afterwards, ^the reaction slurry was allowed to stand until stratified, and then the acid hydrolysis solution containing Ca was obtained by suction filtration, and the acid hydrolysis solution was taken for detection, and the ^Ca content in the acid hydrolysis solution was found to be 13.65% (mass percentage).

(2) Preparation of calcium sulfate whiskers

With the acidolysis solution that contains Ca2 ⁺ obtained in step (1) and the sulfuric acid of mass concentration 90% as raw material, the consumption of sulfuric acid is: ^Ca in the acidolysis solution When fully reacting with sulfuric acid, 100% of the theoretical amount of sulfuric acid required %; the acid hydrolysis solution containing Ca2 ⁺ prepared by step (1) is added to the reaction vessel, then under stirring, sulfuric acid is added through an opening of the reaction vessel, and the condenser is connected through another opening of the reaction vessel to condense The temperature outside the tube is tap water at room temperature (26°C) to cool and reflux the nitric acid vapor volatilized in the reaction process into the reaction slurry, the stirring speed is 250r/min, the reaction temperature is 60°C, and the reaction time is 2.5 hours; The calcium sulfate whiskers were separated by filtration, and the separated calcium sulfate whiskers were washed with distilled water for 4 times and denatured alcohol for 4 times, and then dried at 80°C for 60 minutes to remove surface moisture. The obtained whiskers were in the shape of white needles , Observing calcium sulfate whiskers under an electron microscope: 600-800 μm in length and 10-20 μm in diameter, its morphology under an electron microscope is shown in Figure 4.

(3) Preparation of phosphoric acid

The filtrate obtained by filtering in step (2) is subjected to 2-stage countercurrent extraction, the extractant is composed of trioctylamine and n-octanol, the volume ratio of trioctylamine and n-octanol=5:1, the ratio of the filtrate to the extractant Volume ratio=5:1, extraction temperature 60°C, extraction residence time 60 minutes, raffinate aqueous phase is phosphoric acid (post-treatment such as concentration or impurity removal can be carried out as required); the extracted organic phase separated by countercurrent extraction is carried out with soft water for 2 Stage countercurrent back extraction, the volume ratio of the extracted organic phase to soft water = 5:1, the back extraction temperature is 60°C, the washing residence time is 60 minutes, and the nitric acid obtained by the back extraction is used for the acid hydrolysis of the phosphate rock powder.

Claims (10)

1. the coproduction method of calcium sulfate whisker and phosphoric acid is characterized in that processing step is as follows: (1) Acid hydrolysis of phosphate rock powder The phosphate rock powder is acidolyzed with hydrochloric acid with a mass concentration of 15-26% or with nitric acid with a mass concentration of 30-54%. Or 100% to 130% of the theoretical amount of nitric acid, the slurry after acidolysis of phosphate rock powder is filtered to obtain an acidolysis solution containing Ca ²⁺ ; (2) Preparation of calcium sulfate whiskers The acid hydrolysis solution containing Ca2 ⁺ obtained in step (1) and the sulfuric acid with a mass concentration of 20 to 90% are used as raw materials, and the consumption of the sulfuric acid is: the sulfuric acid required when the Ca2 ⁺ in the acidolysis solution reacts completely with sulfuric acid 100% of the theoretical amount, add the sulfuric acid into the Ca2 ⁺ -containing acidolysis solution under stirring, and react at normal pressure at 50-90°C. The hydrochloric acid vapor or nitric acid vapor volatilized during the reaction is cooled with water Cooling and refluxing into the reaction slurry, the reaction time is at least 1.5 hours, after the reaction is completed, the calcium sulfate whiskers are separated by filtration, and then the obtained calcium sulfate whiskers are washed and dried; (3) Preparation of phosphoric acid The filtrate obtained by filtering in step (2) is subjected to countercurrent extraction, the raffinate aqueous phase is phosphoric acid, the volume ratio of the filtrate to the extractant is 1:1 to 5:1, the extraction temperature is 20 to 60°C, and the extraction residence time is 5 ~60 minutes. 2. The co-production method of calcium sulfate whiskers and phosphoric acid according to claim 1, characterized in that the phosphate rock powder is medium and low-grade phosphate rock powder with a particle size≤1165 μm. 3. according to the coproduction method of calcium sulfate whisker described in claim 1 and 2 and phosphoric acid, it is characterized in that when phosphate rock powder is carried out acidolysis with the hydrochloric acid of mass concentration 15～26%, at first described hydrochloric acid is joined in In the reaction vessel, then add phosphate rock powder to the hydrochloric acid under stirring, and the acid hydrolysis reaction is carried out at normal pressure and room temperature under stirring, and the time is at least 0.5 hour; When the phosphate rock powder is acid-hydrolyzed with nitric acid with a mass concentration of 30-54%, the nitric acid is first added to the reaction vessel, and then the phosphate rock powder is added to the nitric acid under stirring, and the acid hydrolysis reaction is carried out under normal pressure and under stirring. 30 ~ 50 ℃, the time is at least 0.5 hours. 4. according to the coproduction method of calcium sulfate whisker described in claim 1 and 2 and phosphoric acid, it is characterized in that the washing of described calcium sulfate whisker washes with distilled water, technical alcohol successively, and the number of times of washing is at least 2 times. 5. the coproduction method of calcium sulfate whisker and phosphoric acid according to claim 3 is characterized in that the washing of described calcium sulfate whisker washes with distilled water, technical alcohol successively, and the number of times of washing is at least 2 times. 6. according to the coproduction method of calcium sulfate whisker described in claim 1 and 2 and phosphoric acid, it is characterized in that when filtering gained filtrate in step (2) and carry out countercurrent extraction, extraction agent is by trioctylamine and n-octanol Composition, the volume ratio of trioctylamine and n-octanol=2:1～5:1. 7. the coproduction method of calcium sulfate whisker according to claim 3 and phosphoric acid, it is characterized in that when filtering gained filtrate in step (2) and carrying out countercurrent extraction, extraction agent is made up of trioctylamine and n-octanol, The volume ratio of trioctylamine to n-octanol=2:1～5:1. 8. the coproduction method of calcium sulfate whisker according to claim 5 and phosphoric acid, it is characterized in that when filtering gained filtrate in step (2) and carry out countercurrent extraction, extraction agent is made up of trioctylamine and n-octanol, The volume ratio of trioctylamine to n-octanol=2:1～5:1. 9. according to the coproduction method of calcium sulfate whisker described in claim 1 and 2 and phosphoric acid, it is characterized in that the hydrochloric acid or the nitric acid that the extraction organic phase that separates out when carrying out countercurrent extraction to described filtrate carries out countercurrent back extraction with soft water It is used for the acidolysis of phosphate rock powder. During back extraction, the volume ratio of the extracted organic phase to soft water is 0.5:1~5:1, the back extraction temperature is 20~60°C, and the washing residence time is 5~60 minutes. 10. the coproduction method of calcium sulfate whisker and phosphoric acid according to claim 8 is characterized in that the hydrochloric acid or nitric acid that the extraction organic phase that separates out when carrying out countercurrent extraction to described filtrate carries out countercurrent back extraction with soft water is used for For the acid hydrolysis of phosphate rock powder, during stripping, the volume ratio of the extracted organic phase to soft water = 0.5:1-5:1, the stripping temperature is 20-60°C, and the washing residence time is 5-60 minutes.

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