Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The phosphogypsum filling curing agent is used because the main component of phosphogypsum is calcium sulfate dihydrate (CaSO4·2H2 O), the phosphogypsum does not have hydraulic property, the filling slurry formed by mixing the phosphogypsum with water has no strength, and curing materials are needed to be added to bond the phosphogypsum so as to form the strength of the filling slurry.
The problem of using pure Portland cement as a filling curing agent is that conventional curing agent micro Portland cement is a representative hydraulic material, but the Portland cement single cementing material is adopted to cure a large amount of phosphogypsum, and the initial setting time of filling slurry is usually more than 48 hours. The gypsum component in phosphogypsum and soluble phosphorus react with silicate cement to prevent the progress of the hydration reaction of the silicate cement from being delayed, so that the retarding time of the phosphogypsum is greatly delayed and the early strength of the phosphogypsum is greatly reduced, and meanwhile, the hydration product of the system contains a large amount of Ca (OH)2 to cause high pH value, so that the performance application requirements of setting time, early strength, pH value and the like are difficult to meet.
The problems of the filling curing agent, namely, the realization of the granulated blast furnace slag powder reacts with phosphogypsum and Ca (OH)2 which is cement or lime hydration product to generate hydration products such as ettringite, C- (A) -S-H gel and the like, the system can realize the improvement of the mechanical properties of hardening cementing to a certain extent, but the system still does not solve the problems of long setting time, high alkalinity and low early strength caused by the blocking effect of phosphogypsum on the hydration reaction of the composite cementing material.
In order to solve the problems, the technical conception of the invention is as follows:
In one aspect of the invention, a low-alkalinity, early-strength phosphogypsum filling and curing material is provided, and in an exemplary embodiment, the raw material formulation of the low-alkalinity, early-strength phosphogypsum filling and curing material comprises phosphogypsum, a curing agent and water, wherein the curing agent comprises silica fume, limestone powder, superfine granulated blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether.
The invention can solve the technical problems of phosphogypsum retarder, low early strength and high alkalinity, so as to meet the technical requirements of phosphogypsum cemented filling.
The exemplary embodiment of the invention solves the problems of the conventional phosphogypsum of slow setting and low early strength:
(1) Based on the characteristic that phosphogypsum and water in phosphogypsum filling slurry are sufficient, components of silicate cement, aluminate cement, granulated blast furnace slag powder and metakaolin in the curing agent react with gypsum under the condition of sufficient water, so that the cementing and curing effects are achieved.
The C3 A component in the Portland cement is hydrated to form hydrated calcium aluminate (C3AH6), which continuously reacts with gypsum and water to form high hydration reaction products, ettringite (C6AS3H32), and the generated ettringite is covered on the surface of cement particles to prevent further reaction of the Portland cement particles, and soluble phosphorus in the phosphogypsum also forms insoluble matters with the Portland cement to prevent the reaction from proceeding, so that the phosphogypsum filling body is seriously delayed. The aluminate cement is cement with calcium aluminate as main mineral composition, and mainly comprises monocalcium aluminate (CA) and monocalcium dialuminate (C2 A), which also react with gypsum in a system to produce ettringite to cover the surface, but the aluminum phase in the aluminate cement particles is sufficient, part of aluminate ions are dissolved into water through the actions of infiltration, dissolution and the like, and react with the gypsum successively to form hydration products to interweave and construct among various particles, so that the initial setting time of the system is greatly shortened, and the early strength of the system is ensured. At the same time, the granulated blast furnace slag powder and metakaolin in the curing agent dissolve out aluminosilicate ions, silicate ions and the like under the action of calcium hydroxide which is a cement hydration product, and react with gypsum phase to produce hydration products C- (A) -S-H gel and ettringite, so that phosphogypsum filling bodies are continuously compacted, and the later strength is increased.
(2) The aluminate cement, metakaolin and limestone in the curing agent can react with gypsum and silicate cement hydration products in the system, thereby playing a role in cementing and curing.
The calcium aluminate, superfine limestone powder (the main component is calcium carbonate) and calcium hydroxide in the exemplary embodiment of the invention generate hydrated calcium carbonate aluminate, the reaction is mainly in the early stage of hydration, the hydration rate is high, and the early setting time and early strength of phosphogypsum filling slurry can be regulated and controlled. Amorphous aluminosilicate (AlSi2 O) in metakaolin dissolves out under alkaline condition, and can react with calcium hydroxide, gypsum and limestone powder (calcium carbonate) to generate C- (A) -S-H, hydrated calcium carbonate and ettringite to form strength, and the formed hydrated calcium carbonate is compact and provides strength for filling bodies, and the reaction is mainly in the middle and later stages of the system reaction.
In the embodiment, the phosphogypsum is undisturbed phosphogypsum which is not subjected to high temperature treatment by means of calcination and the like, the phosphogypsum can be dihydrate phosphogypsum obtained by drying wet phosphogypsum to constant weight within 40 ℃, and the phosphogypsum accounts for more than or equal to 65% of the dry material by mass, wherein the dry material refers to the phosphogypsum and the curing agent.
In the embodiment, the production raw material formula can comprise, by mass, 65-75 parts of phosphogypsum (based on dry basis), 25-35 parts of curing agent and 27-34% of water based on the sum of the phosphogypsum and the curing agent.
The curing agent comprises, by mass, 4-6% of silica fume, 9-11% of limestone powder, 36-41% of ultrafine granulated blast furnace slag powder, 8-12% of metakaolin, 6-8% of calcium aluminate powder, 28-32% of silicate cement clinker powder, 0.3-3% of a suspension stabilizer and 0.5-1.5% of hydroxypropyl methyl cellulose ether.
Illustratively, the silica fume can be semi-encrypted or fully-encrypted silica fume, the silica content is more than or equal to 95%, the activity index is more than or equal to 110%, and the water demand ratio is less than or equal to 125%.
Illustratively, the limestone powder has a calcium carbonate content of 80% or more and a fineness of 1000 mesh or more.
Illustratively, the specific surface area of the superfine granulated blast furnace slag powder is more than or equal to 600m2/kg, and the 28d activity index is more than or equal to 105%. In this specific surface area range, granulated blast furnace slag is more reactive and activated.
Illustratively, the metakaolin powder can be a powder material which is obtained by calcining kaolin minerals at 600-900 ℃ and takes amorphous aluminosilicate as a main component, wherein Al2O3 is more than or equal to 35%, the specific surface area is more than or equal to 600m2/kg, and the 28d activity index is more than or equal to 105%.
Illustratively, the calcium aluminate powder may include monocalcium aluminate and/or monocalcium dialuminate, with a specific surface area of greater than or equal to 400m2/kg,Al2O3 greater than or equal to 50%.
Illustratively, the tricalcium silicate content of the Portland cement clinker powder is more than or equal to 55%, and the specific surface area is more than or equal to 350m2/kg. Illustratively, the portland cement clinker powder may include 50-70% tricalcium silicate, 20-40% dicalcium silicate, 6-12% tricalcium aluminate, and 10-20% tetracalcium aluminoferrite.
For example, the suspension stabilizer (also referred to as a suspension dispersant) may be a pale yellow powder, added to enhance the suspension properties and stability of the particles in the filler slurry. For example, the suspension stabilizer may include a modified vinyl alcohol polymer, a vinyl ester polymer, maltodextrin, and the like.
Illustratively, the hydroxypropyl methylcellulose ether (HPMC) may be white powder, with a 20-thousand viscosity specification, and a purity of industrial purity.
For example, the particle size of phosphogypsum is less than or equal to 4.75mm, and other indexes meet the technical requirements of the existing national standard GB/T23456 phosphogypsum.
Illustratively, the water may be water meeting the requirements of the current industry standard "Water for concrete Standard" JGJ 63.
The exemplary embodiment of the invention solves the mechanism that the alkalinity of the conventional cement-based phosphogypsum filling system is high:
The alkaline reactant generated by the reaction system of the exemplary embodiment of the invention is mainly Portland cement, which only accounts for 28-32% of the curing agent, accounts for 7-12% of the phosphogypsum filler, and has low relative content. The reactant calcium hydroxide is the main source of alkalinity, and silica fume, metakaolin and granulated blast furnace slag in the curing agent all react with the calcium hydroxide to reduce the alkalinity of the system. Meanwhile, the curing agent of the exemplary embodiment of the invention provides strength aluminate cement and limestone powder, and the main hydration products of the curing agent hydrate calcium aluminate carbonate and ettringite, and calcium hydroxide is not generated, so that the alkalinity of the whole system is lower.
The low-alkalinity and early-strength phosphogypsum filling and curing material has a good working performance mechanism that the silicate and aluminate cement content in the reaction system is scientific, the setting time is controllable under the phosphogypsum filling system, and the flash setting can not be generated. The silica fume in the system plays a role in lubricating glass microspheres, the suspension dispersing agent in the system can suspend phosphogypsum in water well, slurry is stabilized, the slurry has a good flow state, the hydroxymethyl ethyl cellulose can play a role in water retention, and the bleeding of the system is reduced.
In the embodiment, the phosphogypsum can account for more than or equal to 65% of the dry material by mass, the dry material can comprise phosphogypsum and a curing agent, the filling initial setting time of the phosphogypsum filling curing material is less than or equal to 8h, the 3d compressive strength is more than or equal to 1MPa, the 7d compressive strength is more than or equal to 3MPa, the 28d strength is more than or equal to 5MPa, the filling slurry expansion is more than or equal to 800mm, the slurry bleeding rate is less than or equal to 0.5%, and the pH value of the 28d filling body leaching liquid is less than or equal to 10.
According to another aspect of the invention, a preparation method of a low-alkalinity and early-strength phosphogypsum filling and curing material is provided, and the preparation method comprises the steps of uniformly mixing silica fume, limestone powder, superfine granulated blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether to form curing agent powder, uniformly mixing water and the curing agent powder to obtain curing agent slurry, and adding phosphogypsum into the curing agent slurry until the slurry is uniformly mixed to obtain phosphogypsum filling slurry.
In an exemplary embodiment, phosphogypsum accounts for 65% or more of the mass of the dry material, and the dry material comprises phosphogypsum and a curing agent.
The components are 65-75 parts of phosphogypsum (based on dry basis), 25-35 parts of curing agent and 27-34% of water based on the weight ratio of the phosphogypsum to the curing agent.
In the step of forming the curing agent powder, the weight percentage of the curing agent powder is 4-6% of silica fume, 9-11% of limestone powder, 36-41% of ultrafine blast furnace slag powder, 8-12% of metakaolin, 6-8% of calcium aluminate powder, 28-32% of silicate cement clinker powder, 0.3-3% of suspension stabilizer and 0.5-1.5% of hydroxypropyl methyl cellulose ether.
Illustratively, the limestone powder can be semi-encrypted or fully-encrypted silica fume, the silica content is more than or equal to 95%, the activity index is more than or equal to 110%, and the water demand ratio is less than or equal to 125%.
Illustratively, the limestone powder has a calcium carbonate content of 80% or more and a fineness of 1000 mesh or more.
Illustratively, the specific surface area of the superfine granulated blast furnace slag powder is more than or equal to 600m2/kg, and the 28d activity index is more than or equal to 105%.
Illustratively, the metakaolin powder can be a powder material which is obtained by calcining kaolin minerals at 600-900 ℃ and takes amorphous aluminosilicate as a main component, wherein Al2O3 is more than or equal to 35%, the specific surface area is more than or equal to 600m2/kg, and the 28d activity index is more than or equal to 105%.
Illustratively, the calcium aluminate powder may include monocalcium aluminate and/or monocalcium dialuminate, with a specific surface area of greater than or equal to 400m2/kg,Al2O3 greater than or equal to 50%.
Illustratively, the tricalcium silicate content of the Portland cement clinker powder is more than or equal to 55%, and the specific surface area is more than or equal to 350m2/kg.
The suspension stabilizer may be illustratively a pale yellow powder, which is added to enhance the suspension properties and stability of the particles in the filler slurry. For example, the suspension stabilizer may include a modified vinyl alcohol polymer, a vinyl ester polymer, maltodextrin, and the like.
Illustratively, the hydroxypropyl methylcellulose ether (HPMC) may be white powder, with a 20-thousand viscosity specification, and a purity of industrial purity.
For example, the particle size of phosphogypsum is less than or equal to 4.75mm, and other indexes meet the technical requirements of the existing national standard GB/T23456 phosphogypsum.
Illustratively, the water may be water meeting the requirements of the current industry standard "Water for concrete Standard" JGJ 63.
In the embodiment, the phosphogypsum can account for more than or equal to 65% of the dry material by mass, the dry material can comprise phosphogypsum and a curing agent, the filling initial setting time of the phosphogypsum filling curing material is less than or equal to 8h, the 3d compressive strength is more than or equal to 1MPa, the 7d compressive strength is more than or equal to 3MPa, the 28d strength is more than or equal to 5MPa, the filling slurry expansion is more than or equal to 800mm, the slurry bleeding rate is less than or equal to 0.5%, and the pH value of the 28d filling body leaching liquid is less than or equal to 10.
In another exemplary embodiment, the method of preparing the low alkalinity, early strength phosphogypsum filling and curing material of the above exemplary embodiment comprises the steps of:
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, weighing all the raw materials according to the formula amount of the production raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, uniformly adding phosphogypsum into the curing agent slurry until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, pouring phosphogypsum filling slurry into the filling position to be filled, and forming and curing until the phosphogypsum filling slurry reaches 3d or more to obtain the filling body with strength.
In the exemplary embodiment, the preparation method of the low-alkalinity and early-strength phosphogypsum filling and curing material can be used for backfilling the phosphogypsum filling slurry into the goaf of the underground mine, the filling body gradually forms strength along with the progress of hydration reaction, the top plate of the underground goaf is supported after consolidation hardening, the earth surface settlement is prevented, the recovery rate of phosphate ores is improved, the safe and efficient recovery of resources is realized, and the environmental problem caused by the accumulation of solid wastes on the earth surface can be effectively relieved.
In an exemplary embodiment, the low alkalinity, early strength phosphogypsum filled and cured material can be prepared by the preparation method.
In an exemplary embodiment, the low alkalinity, early strength phosphogypsum filled and cured material prepared by the preparation method or the application of the low alkalinity, early strength phosphogypsum filled and cured material in the cured material used for phosphogypsum cemented filling technology.
In the embodiment, the filling body can be backfilled to the goaf of the underground mine, and the filling body gradually forms strength along with the progress of hydration reaction, and supports the top plate of the underground goaf after solidification and hardening.
For a better understanding of the above-described exemplary embodiments of the present invention, they are further described below in conjunction with specific examples. The raw material sources and specific component compositions used in the following examples are identical, for example, the portland cement clinker powder in example 1 is identical to the portland cement clinker powder itself in example 2.
Example 1
The low alkalinity and early strength phosphogypsum filling and curing material is prepared according to the following steps:
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 70 parts of phosphogypsum dihydrate (based on dry basis), 30 parts of curing agent component, and 32% of water based on the sum of the phosphogypsum and the curing agent. Wherein, the curing agent comprises 5% of silica fume, 10% of limestone powder, 38% of superfine blast furnace slag powder, 10% of metakaolin, 7% of calcium aluminate powder, 30% of silicate cement clinker powder, 1% of suspension stabilizer and 1% of hydroxypropyl methyl cellulose ether according to the mass ratio. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, uniformly adding phosphogypsum into the curing agent slurry until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The detection method of the above items is carried out according to the following mode that the filling slurry expansion degree and bleeding rate test method is carried out according to the current national standard of common concrete mixture performance test method standard GB/T50080. The method for testing the setting time of the filling slurry is carried out according to the current national standard GB/T1346 for testing the water consumption, setting time and stability of the cement standard consistency. Compressive strength testing is performed in JGJ70, the current industry standard, building mortar basic Performance test method. pH test the test block cured to 28d age is crushed until the maximum grain diameter is not more than 4.75mm, mixed with deionized water according to the solid-to-liquid ratio of 1:10, and after standing for 24d, the supernatant is taken, and the pH value is tested by a pH meter.
Example 2
The low alkalinity and early strength phosphogypsum filling and curing material is prepared according to the following steps:
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 65 parts of phosphogypsum dihydrate (based on dry basis), 35 parts of curing agent component, and 31% of water based on the sum of the phosphogypsum and the curing agent. Wherein the curing agent comprises 5% of silica fume, 10% of limestone powder, 36% of superfine granulated blast furnace slag powder, 9% of metakaolin, 8% of calcium aluminate powder, 32% of silicate cement clinker powder, 0.5% of suspension stabilizer and 0.8% of hydroxypropyl methyl cellulose ether. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Example 3
The low alkalinity and early strength phosphogypsum filling and curing material is prepared according to the following steps:
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 75 parts of phosphogypsum dihydrate (based on dry basis), 25 parts of curing agent component, and 32% of water in weight ratio of the sum of the phosphogypsum and the curing agent. Wherein the curing agent comprises 4% of silica fume, 9% of limestone powder, 41% of superfine granulated blast furnace slag powder, 8% of metakaolin, 6% of calcium aluminate powder, 32% of silicate cement clinker powder, 0.5% of suspension stabilizer and 0.8% of hydroxypropyl methyl cellulose ether. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to perform slurry test on the expansibility, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Example 4
The low alkalinity and early strength phosphogypsum filling and curing material is prepared according to the following steps:
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 65 parts of phosphogypsum dihydrate (based on dry basis), 35 parts of curing agent component, and 30% of water based on the weight ratio of the phosphogypsum and the curing agent. Wherein the curing agent comprises 4% of silica fume, 9% of limestone powder, 39% of superfine granulated blast furnace slag powder, 8% of metakaolin, 8% of calcium aluminate powder, 32% of silicate cement clinker powder, 0.5% of suspension stabilizer and 0.8% of hydroxypropyl methyl cellulose ether. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Comparative example 1:
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 70 parts of phosphogypsum dihydrate (based on dry basis), 30 parts of P.O 42.5 ordinary Portland cement, and 34% of water in weight ratio of the sum of phosphogypsum and P.O 42.5 ordinary Portland cement. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing water and P.O42.5 ordinary Portland cement powder in a stirring device to obtain slurry.
S4, adding the phosphogypsum into the slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S5, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Comparative example 2
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 70 parts of phosphogypsum dihydrate (calculated on a dry basis) and 30 parts of curing agent, wherein in the curing agent, 60% of granulated blast furnace slag powder, 30% of P.O 42.5 ordinary Portland cement component and 10% of lime are added, and water accounts for 34% of the sum of phosphogypsum and P.O 42.5 ordinary Portland cement in percentage by weight. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing water and P.O42.5 ordinary Portland cement powder in a stirring device to obtain slurry.
S4, adding the phosphogypsum into the slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S5, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Comparative example 3
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 65 parts of phosphogypsum dihydrate (based on dry basis), 35 parts of curing agent component, and 34% of water in weight ratio of the sum of the phosphogypsum and the curing agent. 5% of silica fume, 10% of limestone powder, 35% of superfine granulated blast furnace slag powder, 20% of metakaolin, 15% of calcium aluminate powder, 15% of silicate cement clinker powder, 0.5% of suspension stabilizer and 0.8% of hydroxypropyl methyl cellulose ether.
And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Comparative example 4
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 80 parts of phosphogypsum dihydrate (based on dry basis), 20 parts of curing agent component, and 32% of water in weight ratio of the sum of the phosphogypsum and the curing agent. Wherein, the curing agent comprises 5% of silica fume, 10% of limestone powder, 38% of superfine blast furnace slag powder, 10% of metakaolin, 7% of calcium aluminate powder, 30% of silicate cement clinker powder, 1% of suspension stabilizer and 1% of hydroxypropyl methyl cellulose ether according to the mass ratio. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Comparative example 5
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 70 parts of phosphogypsum dihydrate (based on dry basis), 30 parts of curing agent component, and 32% of water based on the sum of the phosphogypsum and the curing agent. Wherein, the curing agent comprises 5% of silica fume, 28% of limestone powder, 30% of metakaolin, 7% of calcium aluminate powder, 30% of silicate cement clinker powder, 1% of suspension stabilizer and 1% of hydroxypropyl methyl cellulose ether according to the mass ratio. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Comparative example 6
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 70 parts of phosphogypsum dihydrate (based on dry basis), 30 parts of curing agent component, and 31% of water based on the sum of the phosphogypsum and the curing agent. Wherein the curing agent comprises 5% of silica fume, 19% of limestone powder, 36% of superfine granulated blast furnace slag powder, 8% of calcium aluminate powder, 32% of silicate cement clinker powder, 0.5% of suspension stabilizer and 0.8% of hydroxypropyl methyl cellulose ether. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to test the expansion degree, taking part of filling slurry to test the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7 mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Comparative example 7
S1, drying wet phosphogypsum to constant weight at 40 ℃ and calculating the water content of the phosphogypsum.
S2, 65 parts of phosphogypsum dihydrate (based on dry basis), 35 parts of curing agent component, and 31% of water based on the sum of the phosphogypsum and the curing agent. Wherein, the limestone powder is 10%, the superfine granulated blast furnace slag powder is 41%, the metakaolin is 9%, the calcium aluminate powder is 8% and the silicate cement clinker powder is 32%. And weighing all the raw materials, wherein the weighed phosphogypsum raw materials are dry phosphogypsum mass converted by water content, and the weighed water should discount the water content in the wet phosphogypsum.
S3, uniformly mixing silica fume, limestone powder, superfine blast furnace slag powder, metakaolin, calcium aluminate powder, silicate cement clinker powder, a suspension stabilizer and hydroxypropyl methyl cellulose ether required by the curing agent component in a dry mixing device to form filling curing agent powder.
And S4, uniformly mixing the water and the curing agent powder in a stirring device to obtain curing agent slurry.
S5, adding the phosphogypsum into the curing agent slurry at a constant speed until the slurry is uniformly mixed, and obtaining phosphogypsum filling slurry.
S6, taking part of filling slurry to perform slurry test on the expansibility, taking part of filling slurry to perform slurry test on the bleeding rate, and filling the rest phosphogypsum filling slurry into a setting time mould and a 70.7X10.7X10.7mm triple mould to be respectively used for setting time test and compressive strength test, and testing the compressive strength and the pH value of leaching liquid after curing to a specified age.
The material detection method is the same as that of example 1, and will not be described here again.
Fig. 1 shows the material detection results of phosphogypsum filled with the cured material according to the examples and comparative examples of the present invention.
Referring to FIG. 1, it is apparent from comparative example 1 that conventional Portland cement has a long initial setting time (1460 min), low early strength (3 d non-strength), and high strength. As can be seen from comparative example 2, the curing agent system consisting of the conventional mineral admixture, lime and cement still has the problems of low early strength and high alkalinity, and the test piece is cracked as observed in test 28d, so that the system has the problem of volume stability.
As can be seen from comparative example 3, when the Portland cement proportion in the setting agent system is changed by 20%, the phosphogypsum is acidic as a whole, and the system cannot provide enough alkalinity, so that granulated blast furnace slag powder and metakaolin dissolve out silicon and aluminum silicon ions to form hydration products. And the system has the advantages that the calcium aluminate cement content is high, the hydration reaction is rapidly covered on the curing agent particles, and the final strength is affected.
As is clear from comparative example 4, when the proportion of the curing agent was reduced to 20%, sufficient strength could not be formed.
As is clear from comparative example 5, the mechanical properties of the system are reduced due to the lack of the reaction of the granulated blast furnace slag powder with gypsum and cement hydration products by adjusting the proportion of the granulated blast furnace slag powder in the setting agent, and by increasing the limestone powder and metakaolin components. And because the metakaolin needs higher water, the viscosity of the system is increased, and the expansion degree is reduced to 740mm.
As is clear from comparative example 6, when the curing agent system contains no metakaolin component, the reaction with calcium hydroxide, calcium carbonate and calcium aluminate, which are hydration products of Portland cement clinker powder, cannot be exerted, and the mechanical properties of the system are reduced.
As is clear from comparative example 7, in the absence of silica fume, hydroxypropyl methylcellulose ether and suspension stabilizer components in the curing agent system, the bleeding rate of the system increased substantially to 3% and the slurry spread decreased.
The invention aims at the defects of long initial setting time, low early strength, high pH value of the filling material and high bleeding rate of the phosphogypsum filling material in the prior art. According to the technical scheme, under the condition that the phosphogypsum is doped greatly (the phosphogypsum accounts for more than or equal to 65% of the dry material), the filling initial setting time is less than or equal to 8h, the 3d compressive strength is more than or equal to 1MPa, the 7d compressive strength is more than or equal to 3MPa, the 28d strength is more than or equal to 5MPa, the filling slurry expansion degree is more than or equal to 800mm, the slurry bleeding rate is less than or equal to 0.5%, the pH value of the 28d filling body leaching liquid is less than or equal to 10, and d in 3d, 7d and 28d refers to days.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.