Self-leveling preparation method of water-washing neutralized low-impurity phosphogypsum

Abstract

The invention relates to the technical field of ardealite self-leveling, in particular to a washing-neutralized low-impurity ardealite self-leveling preparation method, which comprises the following steps: taking an ardealite raw material, washing with clear water or soft water through spraying equipment or stirring equipment for 5-10 minutes at the washing temperature of 10-40 DEG C, and completely washing. Through washing and neutralizing treatment, soluble phosphorus, soluble fluorine, organic matters, other heavy metals and other impurities in the phosphogypsum are effectively removed, so that the impurity content of a final product is greatly reduced, waste of water resources and the cost of wastewater treatment are reduced through recycling of a washing solution and recycling of filtrate, and meanwhile, the production cost is reduced. Through a fine preparation process, the utilization rate of the raw materials is increased, the production cost is reduced, the environment-friendly and sustainable development concepts are met, and green transformation and sustainable development of the building material industry are promoted through reduction of emission of harmful substances and effective utilization of resources.

Description

Technical Field

[0001] The invention relates to the technical field of phosphogypsum self-leveling, and in particular to a method for preparing water-washed neutralized low-impurity phosphogypsum self-leveling. Background Art

[0002] At present, phosphogypsum self-leveling agent mainly uses calcium sulfate resources in phosphogypsum, which has certain gelling properties, so it is widely used in the field of building materials. It is used as the main raw material or additive and treated through a specific process to give the self-leveling material good fluidity, stability and construction performance;

[0003] At present, the hazards of phosphogypsum in the use of self-leveling mainly come from the impurities it contains, such as soluble phosphorus, soluble fluorine, organic matter and other heavy metals, which will have adverse effects on the environment and human health. Due to the lack of processing costs and processes, the phosphogypsum is not adequately processed in the early stage of preparation for self-leveling, resulting in a large amount of unqualified and harmful phosphogypsum self-leveling on the market. Therefore, a method for preparing water-washed and low-impurity phosphogypsum self-leveling is proposed. Summary of the invention

[0004] In view of the problems in the prior art, the present invention provides a method for preparing a water-washed and neutralized low-impurity phosphogypsum self-leveling. Through water washing and neutralization treatment, impurities such as soluble phosphorus, soluble fluorine, organic matter and other heavy metals in the phosphogypsum are effectively removed, so that the impurity content of the final product is greatly reduced. Through the recycling of washing liquid and the recovery of filtrate, the waste of water resources and the cost of wastewater treatment are reduced. At the same time, through a sophisticated preparation process, the utilization rate of raw materials is improved and the production cost is reduced. The present invention conforms to the concept of environmental protection and sustainable development, and helps to promote the green transformation and sustainable development of the building materials industry by reducing the emission of harmful substances and the effective utilization of resources.

[0005] The technical solution adopted by the present invention to solve the technical problem is a method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum, which comprises the following specific steps:

[0006] Washable:

[0007] Step 1: Take the phosphogypsum raw material, use clean water or soft water, rinse it through a spray device or a stirring device, the rinsing time is 5-10 minutes, the rinsing temperature is 10-40℃, and it is ready for use after rinsing;

[0008] Step 2: Detect impurities in the rinsed phosphogypsum, and select a phosphate detergent of the required concentration for washing according to the detected content of soluble phosphorus and fluorine, and wash the rinsed phosphogypsum through a stirring device or a filtering washing device to ensure that the detergent and the phosphogypsum are in full contact, wherein the stirring or filtering washing time is 30-60 minutes to ensure that the detergent can fully play a role, the washing temperature is 40-50°C, and the washing is ready for use, and the used detergent is sent to the circulation treatment system;

[0009] Step 3: Use clean water to rinse the phosphogypsum through a spray device or a stirring device. The rinsing time is 10-20 minutes and the rinsing temperature is 10-40°C until the washing liquid is completely discharged to obtain low-impurity phosphogypsum;

[0010] Neutralization:

[0011] Step 1: Prepare the neutralizing agent required for neutralizing phosphogypsum, and prepare the stirring equipment, filtering equipment and drying equipment required for neutralization;

[0012] Step 2: The washed low-impurity phosphogypsum and water are sent to a stirring device for mixing to form a phosphogypsum slurry, a neutralizing agent is taken, and the neutralizing agent is slowly added to the phosphogypsum slurry while stirring to allow full contact and a neutralization reaction to occur, and the stirring time is maintained for 30-60 minutes until the pH value reaches 4-5, thereby obtaining a neutralized phosphogypsum slurry;

[0013] Step 3: sending the neutralized phosphogypsum slurry into a filtering device to filter out a filter cake and a filtrate, recovering the obtained filtrate, and using the obtained filter cake for later use;

[0014] Step 4: Send the filter cake to the drying equipment for drying and sieving to remove the coarse particles and impurities that do not meet the requirements;

[0015] Step 5: calcining the dried and sieved phosphogypsum at 800° C. to further remove impurities and improve performance, thereby obtaining a low-impurity phosphogypsum raw material;

[0016] preparation:

[0017] Step 1: Dry the obtained low-impurity phosphogypsum raw material to remove excess moisture, and further screen it to ensure the fineness and uniformity of the phosphogypsum, and the mesh diameter of the screening equipment is 0.5mm-2mm;

[0018] Step 2: sending the screened phosphogypsum into a calcining device for calcination to convert it into anhydrous gypsum;

[0019] Step 3: Grind the anhydrous gypsum to a fineness that meets the use requirements to obtain gypsum powder;

[0020] Step 4: Mix and stir the gypsum powder with the retarder, plasticizer, reinforcing agent and modifier to complete the preparation and modification to obtain low-impurity phosphogypsum self-leveling.

[0021] Specifically, in the water washing step 2, the used detergent is sent to a plate and frame filter or a vacuum filter, the washing liquid is filtered and precipitated to remove impurities therein, and the filtered washing liquid is sent back to step 2 for use. Before being sent to step 2 for use, the pH value is tested to ensure the use effect.

[0022] Specifically, in the second step of the water washing, the detection of phosphogypsum is carried out through the detection of soluble phosphorus and the detection of soluble fluorine, the detection of soluble phosphorus is one of the following methods: quinoline phosphomolybdic acid weight method, quinoline phosphomolybdic acid volumetric method, ammonium metavanadate spectrophotometry or inductively coupled plasma emission spectrometry, and the detection of soluble fluorine is one of the following methods: ion selective electrode method, distillation method or spectrophotometry.

[0023] Specifically, the neutralizing agent is lime milk or limestone.

[0024] Specifically, in the neutralization step 2, the ratio of phosphogypsum to water is 1:1.2-1.5.

[0025] Specifically, the filtrate in the neutralization step three is recovered to the solvent tank and used as a neutralizer liquid for adjusting the pH value of phosphogypsum in the neutralization step two. The slurry can be prepared with water and phosphogypsum. If the neutralizer liquid can neutralize the phosphogypsum slurry with the required pH value, the slurry does not need to enter the neutralization step three, and directly enters the step four for drying treatment and recycling, which can reduce wastewater discharge and treatment costs.

[0026] Specifically, the stirring equipment in the neutralization step 1 is: a conical stirrer or a tank mixer, the filtering equipment is: a chamber diaphragm filter press or a ceramic filter, and the drying equipment is a drum dryer or a scraper dryer.

[0027] Specifically, the usage ratio of the gypsum powder, retarder, plasticizer, reinforcing agent and modifier is 100:0.3:1:15:2, and the retarder is a polyvinyl alcohol compound or lignin sulfonate, the plasticizer is a polycarboxylic acid, naphthalene or aliphatic water reducer, the reinforcing agent is silica fume, fly ash or slag powder active mineral, and the modifier is a high molecular polymer or latex powder.

[0028] The beneficial effects of the present invention are as follows: through water washing and neutralization treatment, impurities such as soluble phosphorus, soluble fluorine, organic matter and other heavy metals in phosphogypsum are effectively removed, so that the impurity content of the final product is greatly reduced, thereby reducing the potential harm to the environment and human health. After careful treatment and formulation, the low-impurity phosphogypsum self-leveling obtained has better physical and chemical properties, such as higher strength, better fluidity and more stable performance, thereby improving the overall quality and use effect of the product. Through the recycling of washing liquid and the recovery of filtrate, the waste of water resources and the cost of wastewater treatment are reduced. At the same time, through the sophisticated preparation process, the utilization rate of raw materials is improved and the production cost is reduced. The present invention conforms to the concept of environmental protection and sustainable development. By reducing the emission of harmful substances and the effective use of resources, it is helpful to promote the green transformation and sustainable development of the building materials industry, and solves the problems of high impurity content, high treatment cost, unstable product quality and great environmental pressure existing in existing phosphogypsum self-leveling products. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0030] Example 1

[0031] The method for preparing a water-washed neutralized low-impurity phosphogypsum self-leveling according to the present invention comprises the following specific steps:

[0032] Washable:

[0033] Step 1: Take the phosphogypsum raw material, use clean water or soft water to rinse it through a spray device, the rinsing time is 5 minutes, the rinsing temperature is 10℃, and it is ready for use after rinsing;

[0034] Step 2: Detect impurities in the rinsed phosphogypsum, and select a phosphate detergent of the required concentration for washing according to the detected content of soluble phosphorus and fluorine, and wash the rinsed phosphogypsum through a stirring device to ensure that the detergent and the phosphogypsum are in full contact, wherein the stirring washing time is 30 minutes to ensure that the detergent can fully play a role, the washing temperature is 40-50°C, and the detergent is used for standby after washing, and the used detergent is sent to the circulation treatment system;

[0035] Step 3: Use clean water to rinse the phosphogypsum through a spray device. The rinsing time is 10 minutes and the rinsing temperature is 10°C until the washing liquid is completely discharged to obtain low-impurity phosphogypsum.

[0036] Neutralization:

[0037] Step 1: Prepare the neutralizing agent required for neutralizing phosphogypsum, and prepare the stirring equipment, filtering equipment and drying equipment required for neutralization;

[0038] Step 2: The washed low-impurity phosphogypsum and water are sent to a stirring device for mixing to form a phosphogypsum slurry, a neutralizing agent is taken, and the neutralizing agent is slowly added to the phosphogypsum slurry while stirring to allow full contact and a neutralization reaction to occur, and the stirring time is maintained for 30 minutes until the pH value reaches 4, thereby obtaining a neutralized phosphogypsum slurry;

[0039] Step 3: sending the neutralized phosphogypsum slurry into a filtering device to filter out a filter cake and a filtrate, recovering the obtained filtrate, and using the obtained filter cake for later use;

[0040] Step 4: Send the filter cake to the drying equipment for drying and sieving to remove the coarse particles and impurities that do not meet the requirements;

[0041] Step 5: calcining the dried and sieved phosphogypsum at 800° C. to further remove impurities and improve performance, thereby obtaining a low-impurity phosphogypsum raw material;

[0042] preparation:

[0043] Step 1: Dry the obtained low-impurity phosphogypsum raw material to remove excess moisture, and further screen it to ensure the fineness and uniformity of the phosphogypsum, and the mesh diameter of the screening equipment is 0.5mm;

[0044] Step 2: sending the screened phosphogypsum into a calcining device for calcination to convert it into anhydrous gypsum;

[0045] Step 3: Grind the anhydrous gypsum to a fineness that meets the use requirements to obtain gypsum powder;

[0046] Step 4: Mix and stir the gypsum powder with the retarder, plasticizer, reinforcing agent and modifier to complete the preparation and modification to obtain low-impurity phosphogypsum self-leveling.

[0047] The present invention also includes that in the water washing step 2, the used detergent is sent into a plate and frame filter, the washing liquid is filtered and precipitated to remove impurities therein, and the filtered washing liquid is re-sent into the step 2 for use, and before being sent into the step 2 for use, the pH value is tested to ensure the use effect.

[0048] The present invention also includes that in the second step of water washing, the detection of phosphogypsum is carried out through the detection of soluble phosphorus and the detection of soluble fluorine, the detection of soluble phosphorus is carried out by the quinoline phosphomolybdic acid weight method, and the detection of soluble fluorine is carried out by the ion selective electrode method.

[0049] The present invention also includes that the neutralizing agent is lime milk.

[0050] The present invention also includes that in the neutralization step 2, the ratio of phosphogypsum to water is 1:1.2.

[0051] The present invention also includes that the filtrate in the neutralization step three is recovered into a solvent tank and used as a neutralizer liquid for adjusting the pH value of phosphogypsum in the neutralization step two, and can be combined with water and phosphogypsum to prepare a slurry. If the neutralizer liquid can neutralize the phosphogypsum slurry with a required pH value, the slurry does not need to enter the neutralization step three, and directly enters the step four for drying treatment and recycling, which can reduce wastewater discharge and treatment costs.

[0052] The present invention also includes that the stirring equipment in the neutralization step 1 is a conical mixer, the filtering equipment is a chamber diaphragm filter press, and the drying equipment is a drum dryer.

[0053] The present invention also includes that the usage ratio of the gypsum powder, retarder, plasticizer, reinforcing agent and modifier is 100:0.3:1:15:2, and the retarder is a polyvinyl alcohol compound, the plasticizer is a polycarboxylic acid water reducer, the reinforcing agent is silica fume, fly ash or slag powder active mineral, and the modifier is a high molecular polymer.

[0054] Example 2

[0055] The method for preparing a water-washed neutralized low-impurity phosphogypsum self-leveling according to the present invention comprises the following specific steps:

[0056] Washable:

[0057] Step 1: Take the phosphogypsum raw material, use clean water or soft water to rinse it through a stirring device, the rinsing time is 10 minutes, the rinsing temperature is 40°C, and it is ready for use after rinsing;

[0058] Step 2: Detect impurities in the rinsed phosphogypsum, and select a phosphate detergent of the required concentration for washing according to the detected content of soluble phosphorus and fluorine. Wash the rinsed phosphogypsum with a filtering and washing device to ensure that the detergent and the phosphogypsum are in full contact. The filtering and washing time is 60 minutes to ensure that the detergent can fully play its role. The washing temperature is 50°C. After washing, it is ready for use, and the used detergent is sent to the circulation treatment system;

[0059] Step 3: Use clean water to rinse the phosphogypsum through a stirring device, the rinsing time is 20 minutes, the rinsing temperature is 40°C, until the washing liquid is completely discharged, and low-impurity phosphogypsum is obtained;

[0060] Neutralization:

[0061] Step 1: Prepare the neutralizing agent required for neutralizing phosphogypsum, and prepare the stirring equipment, filtering equipment and drying equipment required for neutralization;

[0062] Step 2: The washed low-impurity phosphogypsum and water are sent to a stirring device for mixing to form a phosphogypsum slurry, a neutralizing agent is taken, and the neutralizing agent is slowly added to the phosphogypsum slurry while stirring to allow full contact and a neutralization reaction to occur, and the stirring time is maintained for 60 minutes until the pH value reaches 5, thereby obtaining a neutralized phosphogypsum slurry;

[0063] Step 3: sending the neutralized phosphogypsum slurry into a filtering device to filter out a filter cake and a filtrate, recovering the obtained filtrate, and using the obtained filter cake for later use;

[0064] Step 4: Send the filter cake to the drying equipment for drying and sieving to remove the coarse particles and impurities that do not meet the requirements;

[0065] Step 5: calcining the dried and sieved phosphogypsum at 800° C. to further remove impurities and improve performance, thereby obtaining a low-impurity phosphogypsum raw material;

[0066] preparation:

[0067] Step 1: Dry the obtained low-impurity phosphogypsum raw material to remove excess moisture, and further screen it to ensure the fineness and uniformity of the phosphogypsum, and the mesh diameter of the screening equipment is 2mm;

[0068] Step 2: sending the screened phosphogypsum into a calcining device for calcination to convert it into anhydrous gypsum;

[0069] Step 3: Grind the anhydrous gypsum to a fineness that meets the use requirements to obtain gypsum powder;

[0070] Step 4: Mix and stir the gypsum powder with the retarder, plasticizer, reinforcing agent and modifier to complete the preparation and modification to obtain low-impurity phosphogypsum self-leveling.

[0071] The present invention also includes that in the water washing step 2, the used detergent is sent to a vacuum filter, the washing liquid is filtered and precipitated to remove impurities therein, and the filtered washing liquid is re-sent to the step 2 for use. Before being sent to the step 2 for use, the pH value is tested to ensure the use effect.

[0072] The present invention also includes that in the second step of water washing, the detection of phosphogypsum is carried out through the detection of soluble phosphorus and the detection of soluble fluorine, the detection of soluble phosphorus is carried out by inductively coupled plasma emission spectroscopy, and the detection of soluble fluorine is carried out by spectrophotometry.

[0073] The present invention also includes that the neutralizing agent is limestone.

[0074] The present invention also includes that in the neutralization step 2, the ratio of phosphogypsum to water is 1:1.5.

[0075] The present invention also includes that the filtrate in the neutralization step three is recovered into a solvent tank and used as a neutralizer liquid for adjusting the pH value of phosphogypsum in the neutralization step two, and can be combined with water and phosphogypsum to prepare a slurry. If the neutralizer liquid can neutralize the phosphogypsum slurry with a required pH value, the slurry does not need to enter the neutralization step three and directly enters the step four for drying treatment.

[0076] The present invention also includes that the stirring equipment in the neutralization step 1 is a tank mixer, the filtering equipment is a ceramic filter, and the drying equipment is a scraper dryer.

[0077] The present invention also includes that the usage ratio of the gypsum powder, retarder, plasticizer, reinforcing agent and modifier is 100:0.3:1:15:2, and the retarder is: quality sulfonate, the plasticizer is: aliphatic water reducer, the reinforcing agent is slag powder active mineral, and the modifier is: latex powder.

[0078] When the present invention is used, soluble phosphorus, soluble fluorine, organic matter and other heavy metal impurities in phosphogypsum are removed by water washing and neutralization treatment, and the impurity content of the final product is significantly reduced, thereby reducing the potential threat to the environment and human health. On this basis, after treatment and preparation, the obtained low-impurity phosphogypsum self-leveling has better physical and chemical properties. The mechanical properties of the phosphogypsum self-leveling material can be improved by the blending of mineral materials, including higher strength, better fluidity and more stable performance, thereby comprehensively improving the quality and use effect of the phosphogypsum self-leveling. Through the recycling of washing liquid and the recycling of filtrate, the waste of water resources and the cost of wastewater treatment are effectively reduced, the utilization rate of raw materials is improved, and the production cost is further reduced, which is in line with the concept of environmental protection and sustainable development. Moreover, by reducing the emission of harmful substances and the effective use of resources, it has made positive contributions to promoting the green transformation and sustainable development of the building materials industry, and successfully solved the key problems of high impurity content, high processing cost, unstable product quality and great environmental pressure in existing phosphogypsum self-leveling products.

[0079] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum, characterized in that: The specific steps include: Washable: Step 1: Take the phosphogypsum raw material, use clean water or soft water, rinse it through a spray device or a stirring device, the rinsing time is 5-10 minutes, the rinsing temperature is 10-40℃, and it is ready for use after rinsing; Step 2: Detect impurities in the rinsed phosphogypsum, and select a phosphate detergent of the required concentration for washing according to the detected content of soluble phosphorus and fluorine, and wash the rinsed phosphogypsum through a stirring device or a filtering washing device to ensure that the detergent and the phosphogypsum are in full contact, wherein the stirring or filtering washing time is 30-60 minutes to ensure that the detergent can fully play a role, the washing temperature is 40-50°C, and the washing is ready for use, and the used detergent is sent to the circulation treatment system; Step 3: Use clean water to rinse the phosphogypsum through a spray device or a stirring device. The rinsing time is 10-20 minutes and the rinsing temperature is 10-40°C until the washing liquid is completely discharged to obtain low-impurity phosphogypsum; Neutralization: Step 1: Prepare the neutralizing agent required for neutralizing phosphogypsum, and prepare the stirring equipment, filtering equipment and drying equipment required for neutralization; Step 2: The washed low-impurity phosphogypsum and water are sent to a stirring device for mixing to form a phosphogypsum slurry, a neutralizing agent is taken, and the neutralizing agent is slowly added to the phosphogypsum slurry while stirring to allow full contact and a neutralization reaction to occur, and the stirring time is maintained for 30-60 minutes until the pH value reaches 4-5, thereby obtaining a neutralized phosphogypsum slurry; Step 3: sending the neutralized phosphogypsum slurry into a filtering device to filter out a filter cake and a filtrate, recovering the obtained filtrate, and using the obtained filter cake for later use; Step 4: Send the filter cake to the drying equipment for drying and sieving to remove the coarse particles and impurities that do not meet the requirements; Step 5: calcining the dried and sieved phosphogypsum at 800° C. to further remove impurities and improve performance, thereby obtaining a low-impurity phosphogypsum raw material; preparation: Step 1: Dry the obtained low-impurity phosphogypsum raw material to remove excess moisture, and further screen it to ensure the fineness and uniformity of the phosphogypsum, and the mesh diameter of the screening equipment is 0.5mm-2mm; Step 2: sending the screened phosphogypsum into a calcining device for calcination to convert it into anhydrous gypsum; Step 3: Grind the anhydrous gypsum to a fineness that meets the use requirements to obtain gypsum powder; Step 4: Mix and stir the gypsum powder with the retarder, plasticizer, reinforcing agent and modifier to complete the preparation and modification to obtain low-impurity phosphogypsum self-leveling.

2. The method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum according to claim 1, characterized in that: In the water washing step 2, the used detergent is sent to a plate and frame filter or a vacuum filter, the washing liquid is filtered and precipitated to remove impurities therein, and the filtered washing liquid is sent back to step 2 for use. Before being sent to step 2 for use, the pH value is tested to ensure the use effect.

3. The method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum according to claim 2, characterized in that: In the second step of the water washing, the detection of phosphogypsum is carried out through the detection of soluble phosphorus and the detection of soluble fluorine, the detection of soluble phosphorus is one of the following methods: quinoline phosphomolybdic acid gravimetric method, quinoline phosphomolybdic acid volumetric method, ammonium metavanadate spectrophotometry or inductively coupled plasma emission spectrometry, and the detection of soluble fluorine is one of the following methods: ion selective electrode method, distillation method or spectrophotometry.

4. A method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum according to claim 3, characterized in that: The neutralizing agent is lime milk or limestone.

5. A method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum according to claim 4, characterized in that: In the neutralization step 2, the ratio of phosphogypsum to water is 1:1.2-1.

5.

6. A method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum according to claim 5, characterized in that: The filtrate in the neutralization step three is recovered into the solvent tank and used as a neutralizer liquid for adjusting the pH value of the phosphogypsum in the neutralization step two. The slurry can be prepared with water and phosphogypsum. If the neutralizer liquid can neutralize the phosphogypsum slurry with the required pH value, the slurry does not need to enter the neutralization step three and directly enters the step four for drying.

7. A method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum according to claim 6, characterized in that: The stirring equipment in the neutralization step 1 is: a conical stirrer or a tank mixer, the filtering equipment is: a chamber diaphragm filter press or a ceramic filter, and the drying equipment is a drum dryer or a scraper dryer.

8. The method for preparing a self-leveling water-washed neutralized low-impurity phosphogypsum according to claim 7, characterized in that: The use ratio of the gypsum powder, retarder, plasticizer, reinforcing agent and modifier is 100:0.3:1:15:2, and the retarder is a polyvinyl alcohol compound or lignin sulfonate, the plasticizer is a polycarboxylic acid, naphthalene or aliphatic water reducer, the reinforcing agent is silica fume, fly ash or slag powder active mineral, and the modifier is a high molecular polymer or latex powder.