WO2022036923A1 - Technological process for changing physical and chemical properties of new phosphogypsum by using calcium hydroxide - Google Patents

Abstract

A technological process for changing physical and chemical properties of new phosphogypsum by using calcium hydroxide, relating to the technical field of new phosphogypsum treatment and utilization. In the present invention, an amount of calcium hydroxide is calculated according to a chemical principle and a substance structure theory; and by means of a proper technological process, waste residues produced from a phosphate fertilizer plant, i.e., the new phosphogypsum, are converted into building gypsum in situ without dam building and aging. The present invention is mainly characterized by comprising the following steps: (1) detecting content of water-soluble P₂O₅, P₂O₅ in crystals, water-soluble fluorine, Fe₂O₃, Al₂O₃, NH₄ ⁺, and MgO in the new phosphogypsum; (2) determining mass B of calcium hydroxide or mass C of calcium oxide; (3) uniformly mixing the new phosphogypsum with calcium hydroxide powder accounting for 90-105% of B or calcium oxide powder accounting for 90-105% of C; (4) heating to raise the temperature of the material to 220°C-270°C, and discharging to obtain calcined gypsum powder; (5) mixing the calcined gypsum powder and water according to a mass ratio of 100:(40-50), stirring, putting the mixture into a mold, vibrating, demolding, and transferring and stacking; and (6) curing: placing the obtained product at normal temperature for 28 days, and air-drying to obtain a building gypsum product.

Description

Process flow of calcium hydroxide changing physical and chemical properties of new phosphogypsum technical field

The invention belongs to the technical field of new phosphogypsum treatment and utilization, and in particular relates to a technological process for changing the physicochemical properties of new phosphogypsum by using calcium hydroxide or calcium oxide, so as to convert the new phosphogypsum into a building gypsum product.

Background technique

Food security is related to national security, phosphate fertilizer production is related to grain output, and the rational use of phosphogypsum, the waste residue produced by phosphate fertilizer plants, is related to the sustainable development of the phosphate fertilizer industry.

At present, more than 80% of phosphoric acid is produced by wet phosphoric acid dihydrate process. Wet production of 1t phosphoric acid emits about 4-5t (dry basis) of phosphogypsum.

Phosphogypsum is different from natural gypsum. Although its purity is as high as 90%, in addition to CaSO ₄ ·2H ₂ O, it also contains a small amount of undecomposed phosphate rock, unwashed acid phosphate, soluble fluoride, iron Compounds, aluminum compounds, acidic substances, organic substances and other harmful impurities that endanger human health and biological growth, and improper disposal will cause harm to the environment. For example, the chemical composition/% of phosphogypsum (dry basis) and natural gypsum in a certain place is shown in Table 1-1 and Table 1-2, and the main chemical composition/% of impurities in phosphogypsum samples in different regions is shown in Table 2.

Table 1-1

raw material	MgO	CaO	Fe 2 O 3	Al 2 O 3	SiO2	SO 3	H 2 O
Phosphogypsum	0.18	35.03	1.03	1.16	10.25	45.68	31.9
natural gypsum	1.30	31.2	1.35	1.73	4.8	41.1	16.8

Table 1-2

raw material	Water-soluble P 2 O 5	P 2 O 5 in the crystal	water-soluble fluorine	organic matter	pH
Phosphogypsum	1.0	0.12	0.044	0.12	2.6
natural gypsum	_	-	_	_	6.7

Table 2

The main hazards of phosphogypsum include: ① water-soluble phosphorus-containing compounds and water-soluble fluorine-containing compounds enter rivers and oceans with precipitation, and some infiltrate into soil and groundwater bodies, causing pollution; ② in dry climate conditions, the irritation generated by the volatilization of acidic substances Sexual odors and fines form air pollution.

The Notice of the General Office of the State Council on Printing and Distributing the Pilot Work Plan for the Construction of "Waste-Free Cities" (Guoban [2018] No. 128) clearly pointed out that: strictly control the increment, gradually solve the problems left over from the history of industrial solid waste, and focus on phosphogypsum, etc. Explore and implement the policy of "determining production by use" to achieve a balance between production and consumption of solid waste.

technical problem

At present, large-scale phosphate fertilizer enterprises use wet slag discharge, build dams in valleys, and build pipelines to collect backwater for recycling. According to incomplete statistics, more than 100 million tons of phosphogypsum slag are currently stockpiled in China, and about 30 million tons of phosphogypsum slag will be newly generated every year. Except for about 10% of the comprehensive utilization, the rest of the phosphogypsum slag should be discarded and disposed of. . The piling up of these phosphogypsum slag will not only occupy a lot of land, but also cause pollution and increasing pressure on environmental protection, which has become one of the constraints on the production and development of the phosphate fertilizer industry. According to estimates, a project with an annual output of 800,000 tons of heavy calcium (heavy superphosphate) will discharge 1.86 million tons of phosphogypsum slag annually. The investment in the yard is estimated to be 90 million yuan, and the annual operating cost of the yard is nearly 10 million yuan. It reaches 700,000 square meters, which is equivalent to half of the entire factory. From the perspective of environmental protection and technical safety, the storage of phosphogypsum waste residues is not the best strategy. The new phosphogypsum needs to be built and accumulated for five years before it can be used; during the accumulation and aging process, the wind is blowing, the sun is blowing, and the dust is flying;

technical solutions

The technical solution of the present invention is: a kind of technological process that calcium hydroxide changes the physical and chemical properties of new phosphogypsum, it is characterized in that comprising the following steps:

(1) Content detection of new phosphogypsum related components: The new phosphogypsum with mass of M was subjected to water-soluble P ₂ O ₅ , P ₂ O ₅ in crystals, water-soluble fluorine, Fe ₂ O ₃ , Al ₂ O ₃ , NH ₄ ⁺ and MgO content detection, respectively obtain the quality of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A ₇ ;

(2) Calculate according to the chemical reaction formulas of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A ₇ with calcium hydroxide or calcium oxide respectively, and determine the calcium hydroxide mass B or calcium oxide mass C:

B=1.56A ₁ +0.52A ₂ +1.95A ₃ +1.39A ₄ +2.18A ₅ +2.06A ₆ +1.85A ₇ ;

C=1.18A ₁ +0.39A ₂ +1.47A ₃ +1.05A ₄ +1.65A ₅ +1.56A ₆ +1.40A ₇ ;

(3) Mix evenly: add the new phosphogypsum with mass M and calcium hydroxide powder with mass of 90-105% B or calcium oxide powder with mass of 90-105% C into the twin-shaft mixer for forced mixing;

(4) Heating: add the above-mentioned uniformly mixed material into the heating equipment, and the temperature of the material rises to 220 ℃ ~ 270 ℃ to obtain plaster of paris powder; the mechanical properties of this plaster of paris powder reach the national standard of the People's Republic of China GB/T9776-2008 building Gypsum physical and mechanical properties 3.0 requirements;

(5) hydration: the obtained plaster of paris and water are mixed by mass ratio of 100:40～50, stirred, moulded, vibrated, demoulded in 15～20 minutes, and stacked in transition;

(6) Maintenance: Cover the modules stacked in the transfer field with plastic film to prevent water evaporation. After 28 days at room temperature, the plastic film can be removed, and air-dried in the air to obtain a building gypsum product.

The water-soluble fluorine-containing particles (F ^- , HF, SiF ₆ ^2- ) were removed with Ca(OH) ₂ , and the water-soluble fluorine-containing particles completely existed in the gypsum in the form of CaF ₂ as aggregates, thereby eliminating their pollution to the environment.

Use Ca(OH) ₂ to remove water-soluble P ₂ O ₅ (water-soluble PO ₄ ^3- , water-soluble HPO ₄ ^2- , water-soluble H ₂ PO ₄ ^- , H ₃ PO ₄ ), water-soluble P ₂ O ₅ with Ca The ₃ (PO ₄ ) ₂ form exists in the gypsum as an aggregate, thereby eliminating its influence on the pH and strength of the gypsum product.

Removal of P ₂ O ₅ (CaHPO ₄ 2H ₂ O) in CaSO ₄ .2H ₂ O crystals with Ca(OH) ₂ , a portion of CaHPO ₄ .2H ₂ O from the lattice during frying or calcining During the hydration process, a part of CaHPO ₄ ·2H ₂ O is released from the lattice, and the released CaHPO ₄ ·2H ₂ O reacts with Ca(OH) ₂ to form insoluble Ca ₃ (PO ₄ ) ₂ and H ₂ O. When plaster of paris is hydrated, due to the very low C(H ⁺ ) (10 ^-7 mol·L ^-1 ), PO ₄ ^3- cannot recombine with H ⁺ to form CaHPO ₄ ·2H ₂ O into CaSO ₄ ·2H ₂ O Among the crystals, only Ca ₃ (PO ₄ ) ₂ forms exist in gypsum as aggregates, thereby eliminating its influence on pH and strength of gypsum products.

Use Ca(OH) ₂ to remove water-soluble Fe ³⁺ , stir well, and heat to convert Fe ³⁺ into aggregates (Fe ₂ O ₃ ), preventing them from covering the surface of calcium sulfate crystals and forming a coating.

Use Ca(OH) ₂ to remove water-soluble Al ³⁺ , stir well, and heat to convert Al ³⁺ into aggregates (Al ₂ O ₃ ), preventing them from covering the surface of calcium sulfate crystals, forming a coating and hindering its dissolve or crystallize.

Use Ca(OH) ₂ to remove water-soluble Mg ²⁺ , when the product is exposed in the air, the following reaction occurs: Mg ²⁺ +2OH ^- +CO ₂ =MgCO ₃ ↓+H ₂ O, Mg ²⁺ becomes aggregate (MgCO ₃ ), does not affect the properties of calcium sulfate.

Use Ca(OH) ₂ to remove NH ₄ ⁺ . Under heating conditions, NH ₄ ⁺ and Ca(OH) ₂ generate NH ₃ , which can be recycled.

The reaction between Ca(OH) ₂ and organic matter, the organic matter comes from the organic matter in the phosphate rock and the organic matter additives added in each production process, mainly esters [ethylene glycol methyl ether acetate (boiling point: 145 ℃) , 760mmHg), methyl isothiocyanate (boiling point: 107.8 ℃, 760mmHg)] and ethers [3-methoxy-n-pentane boiling point: (63.3 ℃, 760mmHg)] and so on. Esters undergo hydrolysis under alkaline conditions to form carboxylates and low-boiling ethers. Ethers are very stable under alkaline conditions, and are easily oxidized to peroxides in the air. The peroxides undergo disproportionation reactions under the catalysis of Fe ³⁺ to form low-boiling alcohols. The boiling point of these organic substances is below 200°C, and they can be vaporized and removed by heating for recycling.

In step (3) of the technical solution of the present invention, an aspirator is arranged above the double-shaft mixer to recover and process the ammonia gas generated during the mixing and stirring process. The device uses dilute phosphoric acid as an absorbent to convert ammonia gas into ammonium phosphate.

In step (3) of the technical solution of the present invention, the mass of the calcium hydroxide powder is 98-102% B, and the mass of the calcium oxide powder is 98-102% C.

In the step (3) of the technical solution of the present invention, the quality of the calcium hydroxide powder is B, and the quality of the calcium oxide powder is C.

In step (3) of the technical solution of the present invention, the added amount of the calcium hydroxide powder or calcium oxide powder is based on the pH=6-7 of the plaster of Paris product.

In step (4) of the technical solution of the present invention, the heating equipment is a frying pan, a rotary kiln, a boiling furnace or a pit mill.

In the step (4) of the technical solution of the present invention, the heating equipment is provided with a waste gas recovery and treatment device.

In step (4) of the technical solution of the present invention, the waste gas recovery and treatment device is a waste gas recovery and treatment device that uses cold water as a trapping agent to cool, enrich and concentrate the organic mixture vapor.

In the step (4) of the technical solution of the present invention, the temperature of the material is measured by a temperature measuring device arranged in the material.

beneficial effect

1. Directly use new phosphogypsum as raw material: convert the waste residue produced by the phosphate fertilizer plant---new phosphogypsum into high-quality building gypsum products without aging, creating conditions for the sustainable development of the phosphate fertilizer plant and adding new economic growth points; Contribute to protecting gypsum mineral resources, advocating green chemistry, and building a waste-free city;

2. It can be connected with the slag discharge port of the phosphate fertilizer plant without building a yard;

3. The technological process is simple: mixing - heating - hydration - maintenance, normal pressure operation;

4. Accurate ratio of raw materials: For new phosphogypsum from different origins, according to the chemical composition inspection report of new phosphogypsum, calculate the mass ratio of new phosphogypsum to calcium hydroxide (or the mass ratio of new phosphogypsum to calcium oxide). An appropriate amount of calcium hydroxide (calcium oxide) can completely convert harmful impurities in new phosphogypsum into insoluble substances, which remain in the product as aggregates and do not need to be removed. The product is environmentally friendly, with pH=6～7, which can be compared with natural gypsum;

5. The mechanical properties meet the requirements of the National Standard of the People's Republic of China GB/T9776-2008 Building Gypsum Physical and Mechanical Properties 3.0.

The invention is mainly used for processing new phosphogypsum into building gypsum products in situ.

Description of drawings

Fig. 1 is the production process flow chart of phosphorus gypsum of construction of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1:

See Table 3-1 and Table 3-2 for chemical composition/% of new phosphogypsum samples from a factory.

Table 3-1

Table 3-2

1. Measurement:

According to Table 3-1 and Table 3-2, the contents of water-soluble P ₂ O ₅ , P ₂ O ₅ in crystals, water-soluble fluorine, Fe ₂ O ₃ , Al ₂ O ₃ , NH ₄ ⁺ and MgO are respectively A ₁ = _1.56M %, A2 ₌ 0.12M%, A3= _0.044M %, A4=0.70M%, A5= _0.79M %, A6= _0.0004M % and _A7 =0.12M%, M is a certain The quality of the new phosphogypsum samples from the factory;

According to B=1.56A ₁ +0.52A ₂ +1.95A ₃ +1.39A ₄ +2.18A ₅ +2.06A ₆ +1.85A ₇ , determine the calcium hydroxide mass B=4.6M%;

According to C=1.18A ₁ +0.39A ₂ +1.47A ₃ +1.05A ₄ +1.65A ₅ +1.56A ₆ +1.40A ₇ , determine the quality of calcium oxide C=3.5M%; (calcium oxide reacts with water to generate hydroxide calcium);

If calcium hydroxide or calcium oxide is excessive, the cost will be increased, and the product will be strongly alkaline; if calcium hydroxide or calcium oxide is insufficient, the purpose of completely removing harmful impurities cannot be achieved;

2. Mix and stir:

Add new phosphogypsum (wet base) and calcium hydroxide powder in a mass ratio of 100:4.6 through a metering device, or add new phosphogypsum (wet base) and calcium oxide powder in a mass ratio of 100:3.5 into the mixer for forced Mix evenly; at the same time, turn on the aspirator set above the double-shaft mixer to recover and process the ammonia gas produced by the conversion of NH ₄ ⁺ during the mixing and stirring process;

3. Heating:

The above-mentioned uniformly mixed materials are added to the frying pan, heated so that the temperature of the materials in the frying pan rises to 260 ℃, and then cooled to obtain plaster of paris powder; meanwhile, the waste gas generated during the heating process is enriched and recycled by cold water;

4. Hydration:

Mix the prepared plaster of paris powder with water in a mass ratio of 100:45, stir, mold, vibrate, demould for 15 minutes, and stack in transfer field;

5. Maintenance:

The modules stacked in the transfer field are covered with plastic film to prevent moisture from evaporating. After being placed at room temperature for 28 days, the plastic film is removed and air-dried in the air to obtain a building gypsum product.

The obtained plaster of Paris product test results:

The obtained building gypsum product was subjected to physical and mechanical tests by the Experimental Testing Center of the Eighth Geological Brigade of Hubei Provincial Geological Bureau, and obtained the "Physical and Mechanical Test Report" (MA 171716040411, test batch number: B191015), wherein the physical and mechanical properties are shown in Table 4:

Table 4

The obtained building gypsum product was inspected by the main impurity content of the Experimental Test Center of the Eighth Geological Brigade of the Hubei Provincial Geological Bureau, and obtained the "Inspection Report" (MA 171716040411, report batch number: (2019) A19504), wherein, the main impurity content is shown in Table 5:

table 5

The above test results show that the mechanical properties of the obtained building gypsum products meet the requirements of the National Standard of the People's Republic of China GB/T9776-2008 building gypsum physical and mechanical properties 3.0.

Embodiments of the present invention

The technical process embodiment of calcium hydroxide changing the physical and chemical properties of new phosphogypsum includes the following steps:

(1) Content detection of new phosphogypsum related components: The new phosphogypsum with mass of M was subjected to water-soluble P ₂ O ₅ , P ₂ O ₅ in crystals, water-soluble fluorine, Fe ₂ O ₃ , Al ₂ O ₃ , NH ₄ ⁺ and MgO content detection, respectively obtain the quality of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A ₇ ;

(2) Calculation: Calculate according to the chemical reaction formula of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A ₇ with calcium hydroxide or calcium oxide respectively, and determine the calcium hydroxide mass B or calcium oxide mass C:

B=1.56A ₁ +0.52A ₂ +1.95A ₃ +1.39A ₄ +2.18A ₅ +2.06A ₆ +1.85A ₇ ;

C=1.18A ₁ +0.39A ₂ +1.47A ₃ +1.05A ₄ +1.65A ₅ +1.56A ₆ +1.40A ₇ ;

(3) Mix evenly: add the new phosphogypsum with mass M and calcium hydroxide powder with mass of 90-105% B or calcium oxide powder with mass of 90-105% C into the twin-shaft mixer for forced mixing;

(4) Heating: add the above-mentioned uniformly mixed material into the heating equipment, and the temperature of the material rises to 220 ℃ ~ 270 ℃ to obtain plaster of paris powder; the mechanical properties of this plaster of paris powder reach the national standard of the People's Republic of China GB/T9776-2008 building Gypsum physical and mechanical properties 3.0 requirements;

(5) Hydration: mix the prepared plaster of paris with water in a mass ratio of 100:40-50, stir, mold, vibrate, demould for 15-20 minutes, and stack in transfer field;

(6) Conservation: Cover the modules stacked in the transfer field with plastic film to prevent moisture from evaporating. After 28 days at room temperature, the plastic film can be removed, and air-dried in the air to obtain a building gypsum product.

In step (3) of the embodiment, an aspirator is set above the double-shaft mixer to recover and process the ammonia gas generated during the mixing and stirring process. The device uses dilute phosphoric acid as an absorbent to convert ammonia gas into ammonium phosphate.

In the step (3) of the embodiment, the mass of the calcium hydroxide powder is 98-102% B, and the mass of the calcium oxide powder is 98-102% C.

In the step (3) of the embodiment, the quality of the calcium hydroxide powder is B, and the quality of the calcium oxide powder is C.

In the step (3) of the embodiment, the added amount of the calcium hydroxide powder or calcium oxide powder is based on the pH=6-7 of the plaster of Paris product.

In the step (4) of the embodiment, the heating equipment is a frying pan, a rotary kiln, a boiling furnace or a pit mill.

In the step (4) of the embodiment, the heating equipment is provided with an exhaust gas recovery and treatment device.

In the step (4) of the embodiment, the waste gas recovery and treatment device is a waste gas recovery and treatment device that uses cold water as a trapping agent to cool and enrich the vapor of the organic mixture for centralized treatment.

In the step (4) of the embodiment, the temperature of the material is measured by a temperature measuring device arranged in the material.

Industrial Applicability

1. Directly use new phosphogypsum and calcium hydroxide (or calcium oxide) as raw materials: convert the waste residue produced by the phosphate fertilizer plant---new phosphogypsum into high-quality building gypsum products without aging, creating a sustainable development for the phosphate fertilizer plant. conditions, and increase new economic growth points; contribute to the protection of gypsum mineral resources, the promotion of green chemistry, and the construction of a waste-free city;

2. It can be connected with the slag discharge port of the phosphate fertilizer plant, and no phosphogypsum storage yard will be built;

3. The process is simple: mixing - heating - hydration - maintenance, normal pressure operation;

4. Accurate ratio of raw materials: For new phosphogypsum from different origins, according to the chemical composition inspection report of new phosphogypsum, calculate the mass ratio of new phosphogypsum to calcium hydroxide (or the mass ratio of new phosphogypsum to calcium oxide). An appropriate amount of calcium hydroxide (calcium oxide) can completely convert harmful impurities in new phosphogypsum into insoluble substances, which remain in the product as aggregates and do not need to be removed. The product is environmentally friendly, with pH=6～7, which can be compared with natural gypsum;

5. The mechanical properties meet the requirements of the National Standard of the People's Republic of China GB/T9776-2008 Building Gypsum Physical and Mechanical Properties 3.0.

The present invention is mainly used for processing new phosphogypsum into building gypsum products in situ.

Sequence Listing Free Content

New phosphogypsum is a kind of solid waste that has just left the factory. The principle of calcium hydroxide changing the physical and chemical properties of new phosphogypsum is: the harmful impurities in new phosphogypsum react with calcium hydroxide, and the direction and direction of each reaction are calculated according to the chemical principle. The limit and the residual amount of harmful impurities after the reaction are determined to determine the feasibility of the process; then according to the theory of material structure, the new phosphogypsum is converted into high-quality building gypsum without aging by using an appropriate process. The theoretical calculation results are in good agreement with the experimental measurement data.

Claims (9)

1. A kind of technological process that calcium hydroxide changes the physical and chemical properties of new phosphogypsum, it is characterized in that comprising the following steps:

   (1) Content detection of new phosphogypsum related components: The new phosphogypsum with mass of M was subjected to water-soluble P ₂ O ₅ , P ₂ O ₅ in crystals, water-soluble fluorine, Fe ₂ O ₃ , Al ₂ O ₃ , NH ₄ ⁺ and MgO content detection, respectively obtain the quality of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A ₇ ;

   (2) Calculate according to the chemical reaction formulas of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A ₇ with calcium hydroxide or calcium oxide respectively, and determine the calcium hydroxide mass B or calcium oxide mass C:

   B=1.56A ₁ +0.52A ₂ +1.95A ₃ +1.39A ₄ +2.18A ₅ +2.06A ₆ +1.85A ₇ ;

   C=1.18A ₁ +0.39A ₂ +1.47A ₃ +1.05A ₄ +1.65A ₅ +1.56A ₆ +1.40A ₇ ;

   (3) Mix evenly: add the new phosphogypsum with mass M and calcium hydroxide powder with mass of 90-105% B or calcium oxide powder with mass of 90-105% C into the twin-shaft mixer for forced mixing;

   (4) Heating: adding the above-mentioned uniformly mixed material into the heating equipment, the temperature of the material rises to 220 ℃～270 ℃ and is released, and obtains plaster of paris;

   (5) Hydration: mix the prepared plaster of paris with water in a mass ratio of 100:40-50, stir, mold, vibrate, demould for 15-20 minutes, and stack in transfer field;

   (6) Conservation: Cover the modules stacked in the transfer field with plastic film to prevent water evaporation. After being placed at room temperature for 28 days, the plastic film can be removed, and air-dried in the air to obtain a building gypsum product.
2. The technological process that calcium hydroxide changes the physicochemical properties of new phosphogypsum according to claim 1, it is characterized in that: in the (3) step, an aspirator is set above the described biaxial mixer, and the Ammonia gas recycling.
3. The technological process that calcium hydroxide according to claim 1 and 2 changes the physical and chemical properties of new phosphogypsum, it is characterized in that: in the (4) step, the described heating equipment is a frying pan, a rotary kiln, a boiling furnace or a peter mill .
4. The technological process of changing the physical and chemical properties of new phosphogypsum by calcium hydroxide according to claim 1 or 2 is characterized in that: in step (4), the heating equipment is provided with a waste gas recovery and treatment device.
5. The technological process of changing the physical and chemical properties of new phosphogypsum by calcium hydroxide according to claim 4, characterized in that: the waste gas recovery and treatment device cools, enriches, and concentrates the organic mixture steam by using cold water as a collector. Treated exhaust gas recovery and treatment device.
6. The technological process of changing the physical and chemical properties of new phosphogypsum by calcium hydroxide according to claim 1 or 2, is characterized in that: in step (3), the quality of the calcium hydroxide powder is 98-102% B, calcium oxide The mass of the powder is 98-102%C.
7. The technological process that calcium hydroxide changes the physicochemical properties of new phosphogypsum according to claim 1 and 2, it is characterized in that: in the (3) step, the quality of the calcium hydroxide powder is B, and the quality of the calcium oxide powder is C.
8. The technological process that calcium hydroxide changes the physicochemical properties of new phosphogypsum according to claim 1 and 2, it is characterized in that: in the (4) step, the temperature of the material is measured by a temperature measuring device arranged in the material of.
9. The technological process that calcium hydroxide changes new phosphogypsum physical and chemical properties according to claim 1 or 2, it is characterized in that: in the (3) step, the addition amount of described calcium hydroxide powder or calcium oxide powder is so as to make the building Gypsum product pH=6～7 shall prevail.

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