46 results about "Anhydrite" patented technology

The invention belongs to the field of phosphorus chemical industry, and particularly relates to a method for synchronously preparing type II anhydrite in a semi-hydrated-dihydrated wet-process phosphoric acid process and the type II anhydrite. The method comprises the following steps: carrying out slurry premixing, semi-hydrated crystallization, dihydrate conversion and dihydrate filtration to obtain dihydrate gypsum, after the semi-hydrated crystallization step, leading out a part of slurry, adding a lattice orientation agent and a crystal face selective adsorbent into an intermediate pretreatment tank for pretreatment, and adding concentrated sulfuric acid into an anhydrous crystallization reactor for anhydrous crystallization, and finally, carrying out solid-liquid separation, washing and drying to obtain the type II anhydrite. The method is simple in process, energy-saving and environment-friendly, co-production of the phosphoric acid product and the high-added-value II type anhydrous gypsum is realized, and the product yield is gt; therefore, the method has remarkable economic benefits and environmental benefits.

The invention belongs to the field of building materials, and particularly relates to an anhydrous gypsum-based terrazzo floor material and a preparation method thereof. The anhydrite-based terrazzo floor material is prepared from the following raw materials: anhydrite, quenched stone, building gypsum, ash calcium, potassium sulfate, calcium formate, a water reducing agent, a defoaming agent, rubber powder and hydroxypropyl methyl cellulose. The invention relates to a building material, which is prepared from the following raw materials in parts by weight: 525 to 550 parts of anhydrite, 350 to 450 parts of quenched stone, 30 to 40 parts of building gypsum, 15 to 20 parts of ash calcium, 4 to 7 parts of potassium sulfate, 0.5 to 0.8 part of potassium acid calcium, 1.5 to 2.0 parts of water reducing agent, 0.4 to 0.6 part of defoaming agent, 0.10 to 0.15 part of hydroxypropyl methyl cellulose and 6 to 8 parts of rubber powder. The anhydrous gypsum-based terrazzo floor material is high in early strength and low in cost compared with a cement-based inorganic terrazzo in a construction period. The development of companies is facilitated, and the product is more competitive in the market.

A ternary hydraulic binder composition including the mineralogical compound C4A3$ (ye'elimite) and a member selected from the group consisting of gypsum, calcium sulfate hemihydrate, anhydrite and mixtures thereof (collectively named C$Hx with x being a rational number from 0 to 2), and optionally C2S (belite), including an added content of the mineralogical compound C12A7 (dodecacalcium heptaaluminate). Moreover, it suggests a process for the manufacture thereof, a process for the manufacture of a construction chemical composition including water, and the use of the ternary composition in construction chemical compositions including knifing fillers, screeds, and repair mortars, tile adhesives, tiling grouts, plasters, base coats and sealings.

The application discloses anhydrite calcining system and relates to the technical field of gypsum processing. The anhydrite calcining system comprises a calcining assembly and a crushing assembly. A discharging port is arranged on the calcining assembly. A crushing inlet is arranged on the crushing assembly. A ring-shaped support frame is rotatably arranged on the discharging port. A sealing base plate is installed on the ring-shaped support frame through a sealing connecting assembly. Soft pipes are connected to the ring-shaped support frame through a pipeline connecting assembly. The other ends of the soft pipes are connected to the crushing inlet. The crushing assembly and the calcining assembly are connected through the soft pipes. When the calcining is finished and the discharging is performed, the gypsum product obtained from the calcining assembly is guided from the discharging port to the crushing inlet position. The dust in the product is also limited between the soft pipes. In this process, the dust can be prevented from being raised into the air.

The application belongs to the technical field of comprehensive utilization of solid waste and building materials, and particularly relates to a method for preparing and activating type II anhydrite, and specific steps are as follows: after the gypsum and a compound conversion agent are measured according to a mass ratio and uniformly mixed, type II anhydrite is obtained by dehydration conversion at 120-200 DEG C for 30-60 min, the type II anhydrite is ground to a specific surface area of 400+ / -20 m 2 / kg, calcium active material and an activator are added and uniformly mixed to obtain type II anhydrite products. The water requirement of the type II anhydrite according to the application at a standard consistency is 40-45% of the mass of the mixture, the initial setting time is 30-60 min, the final setting time is 120-180 min, the 28-day flexural strength is greater than 6 MPa, the compressive strength is greater than 25 MPa, and the softening coefficient is greater than 0.8. Compared with the existing calcination method, the dehydration temperature of the application is low and more energy-saving, and compared with the liquid phase method, the application has a simple process, large capacity, does not need drying, and does not have the problem of water balance in the production process. The application provides a new technology for preparing water-resistant and high-strength gypsum products from gypsum, especially chemical gypsum such as phosphogypsum, and has great significance for promoting the resource utilization of phosphogypsum.

The invention discloses low-carbon environment-friendly self-leveling mortar and a preparation method thereof, and belongs to the technical field of mortar. Comprising the following steps: mixing P.O42.5 cement, 42.5 sulphoaluminate cement, building desulfurization gypsum, S95-grade granulated blast furnace slag powder, a gelling reinforcing filler, silica fume, grading machine-made sand, grading tailing sand and heavy calcium powder, and stirring in a stirrer for 30-50 seconds to obtain a mixed dry material; and adding mixing water, cellulose ether and an auxiliary agent into the mixed dry material, and stirring to obtain the low-carbon environment-friendly self-leveling mortar. The low-carbon environment-friendly self-leveling mortar with good product performance is obtained by optimizing formula composition, selecting granulated blast furnace slag powder, silica fume and fly ash to replace P.O 42.5 cement, selecting grading machine-made sand and tailing sand to replace grading dried river sand, and selecting building desulfurization gypsum to replace natural anhydrous gypsum.

The invention provides an anhydrous ardealite-based foaming door core board and a preparation method thereof.The anhydrous ardealite-based foaming door core board is prepared from anhydrous ardealite, cement, fly ash, water, a foaming agent, short fibers and a modifier.The preparation method includes the steps that the water is added into a stirrer, the short fibers and the modifier are added, then the stirrer is started, dry powder is added, the foaming agent is added after the dry powder is evenly stirred, and the foaming agent is added; adjusting the foaming amount; pouring the slurry into a mold, curing for 2 hours, and demolding; after demolding, the foaming agent is arranged at intervals in a side-standing mode, heat and moisture are dissipated, the foaming agent leaves a factory after being naturally cured for 3-5 days or is dried after being naturally cured for 1 day so as to shorten the factory time, and the modifier promotes the foaming agent to form hundreds of millions of closed thick-wall small round hole structures in the slurry to strongly support the strength of door core plates. Meanwhile, erosion of water and carbon dioxide in air is isolated, excellent durability is kept, and the excellent performance of the gypsum-based fireproof door core plate can be guaranteed; the production process is simple, raw material cost is low, and comprehensive production cost is reduced.

The invention discloses a plugging composition for plugging an oil field water flow dominant channel. The plugging composition contains ultrafine powder, a thickening regulator and a filtration regulator, wherein the ultrafine powder is prepared from 40.5 to 69.2 parts of hexagonal calcium silicate, 11.5 to 28.6 parts of calcite, 5.8 to 14.7 parts of clay mineral, 5.2 to 14.6 parts of quartz, 0 to 0.9 part of potassium feldspar, 0 to 2.6 parts of plagioclase, 0 to 0.6 part of dolomite, 0 to 2.1 parts of hornblende, 0 to 0.4 part of gypsum and 0 to 3.8 parts of anhydrite; the thickening regulator is sodium lignin sulfonate, hydroxymethyl cellulose and / or boric acid; the filtration property regulator is a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxy carboxylic acid, barium sulfate and / or 1788 type polyvinyl alcohol; the mass ratio of the thickening regulator to the ultrafine powder is (0.05-4): 100; the mass ratio of the filtration modifier to the ultrafine powder is (0.5-5): 100. The invention also discloses a preparation method and application thereof. The plugging composition provided by the invention can be matched with water flow dominant channels of reservoirs with different permeability.

The invention relates to the technical field of firework cylinders, in particular to a firework mold pressing cylinder based on cassava flour pregelatinization and a preparation method thereof, and the mold pressing cylinder is prepared from the following raw materials in parts by weight: a framework material compounded by crystal transformation method II type anhydrous gypsum and calcium carbonate stone powder, pregelatinized cassava flour, wood fibers, stearic acid and a proper amount of water. The tapioca flour is pre-gelatinized by warm water at 40-60 DEG C, and the pre-gelatinization degree is greater than or equal to 80 The crystal transformation method II type anhydrous gypsum is prepared from ardealite through a low-temperature crystal transformation method. The preparation method comprises the following steps: pre-gelatinizing the tapioca flour, pulping, mixing with other dry blends and hot water, and finally carrying out high-temperature compression molding. Through the synergistic effect of the pre-gelatinized tapioca flour and the crystal transformation method gypsum, the dry basis dosage of the tapioca flour is remarkably reduced, meanwhile, the compressive strength and the falling resistance of the mold pressing barrel are greatly improved, the multiple purposes of reducing the cost, improving the performance and absorbing industrial solid waste phosphogypsum are achieved, the product quality is stable, and the mold pressing barrel is suitable for industrial production.

The invention belongs to the technical field of concrete materials, and particularly relates to a method for preparing a millstone from a type II anhydrous gypsum base. The II-type anhydrous gypsum-based inorganic millstone concrete is prepared from the following raw materials: II-type anhydrous gypsum, building gypsum, yellow phosphorus slag, ash calcium, an additive, gravel, sand and water. The concrete raw materials comprise, by weight, 34 to 38 parts of II-type anhydrous gypsum, 1 to 3 parts of building gypsum, 1 to 3 parts of yellow phosphorus slag, 1 to 2 parts of ash calcium, 0.4 to 0.6 part of an additive, 25 to 30 parts of rubble with a particle size of 2 to 10 mm, 12 to 17 parts of rubble with a particle size of 10 to 16.5 mm, 12 to 13 parts of sand with a particle size of 20 to 50 meshes, 5 to 6 parts of quartz sand with a particle size of 60 to 90 meshes, and 12 to 13 parts of water. Through scientific and reasonable raw material ratio and rigorous and meticulous preparation process, many problems existing in preparation of the inorganic millstone from the II-type anhydrous gypsum in the prior art are successfully solved.

The application provides a preparation method of anhydrite light self-leveling mortar. The anhydrite self-leveling mortar is prepared by mixing and stirring desulfurization gypsum, lime cement, self-made light gypsum sand, type II anhydrite and an additive in a specific ratio, and the volume density of the anhydrite self-leveling mortar is between 800 Kg / m 3 1000 Kg / m 3 , the 28d absolute dry compressive strength is 31MPa-40MPa, which is far greater than the 28d absolute dry compressive strength (20MPa) of the existing self-leveling mortar, wherein the light gypsum sand with high strength, water resistance, environmental protection and low cost is used in the formula, and the cost of the self-leveling mortar is greatly reduced.

A process for recycling plaster waste from the general public, the process comprises a step (S1) for sorting the solid waste in order to obtain a portion (A) known as gypsum, and a portion (B) known as reject; a step (S2) of generating fuel from at least part of the portion (B) of rejects by an exothermic process; a step (S3) for generating anhydrite from at least part of the gypsum portion (A); the process further comprising the recovery of at least part of the heat (C) generated by the exothermic process, in that the step (S3) of generating anhydrite comprises the heating of the at least part of the portion (A) of gypsum produced from the at least part of the heat (C).

The present application relates to the technical field of inorganic non-metallic materials, and particularly relates to a gypsum-based cementing material and a preparation method thereof, the gypsum-based cementing material comprising the following components in percentage by mass: 25-50% of type 2 anhydrite powder, 10-30% of hemihydrate gypsum powder, 10-20% of cement clinker powder, 20-25% of active micro powder, 3-5% of quicklime, and 1-5% of an activator. The gypsum-based cementing material of the present application is based on type 2 anhydrite and hemihydrate gypsum, and cement clinker powder is added thereto, so that the hydration performance of the cementing material can be significantly improved; the active micro powder and quicklime powder are further added, so that the cementing structure of the cementing material can be improved, a multi-element cementing system is formed, and the stability and durability of the cementing system are significantly improved; and the activator is further added, so that a calcium aluminate cementing body can be quickly formed during the hydration of the cementing material, the hydration conditions are further optimized, and the gypsum-based cementing material is more suitable for construction.

The application provides a high-coating lightweight plastering gypsum and a preparation method thereof. The mechanical strength of the lightweight plastering gypsum prepared by mixing and stirring building gypsum, II anhydrous hard gypsum, self-prepared lightweight gypsum sand, vitrified microbeads and additives in a specific ratio can reach excellent performance such as a tensile bonding strength of 0.6-0.8 MPa under standard conditions and a tensile bonding strength of 0.28-0.4 MPa under humid conditions, which is greatly improved compared with the existing lightweight plastering gypsum with a tensile bonding strength of greater than or equal to 0.3 MPa.

The invention relates to a method for purifying calcium sulfate, in particular for reducing radioactive components, phosphorus-containing or fluorine-containing impurities and heavy metals originating from what is known as phosphogypsum resulting from phosphoric acid production, based on recrystallization of the anhydrite form into the dihydrate form in a sulfuric acid solution and separation into a coarse fraction and a fine fraction, wherein the fine fraction contains the undesired impurities, in particular the radioactive component. The invention also relates to a system for carrying out such a method.

The invention discloses a low-carbon early-strength phosphorus type II anhydrous gypsum epoxy resin-based self-leveling mortar material, which is prepared from the following raw materials: phosphorus type II anhydrous gypsum, epoxy resin, a curing agent, a silane coupling agent, building gypsum, silica fume, fly ash, ground steel slag, carbide slag, calcined sulfate, slag, cement, sand, a plasticizer, a water reducing agent, a retarder, a defoaming agent and water. According to the invention, industrial solid wastes such as anhydrite, fly ash and carbide slag are taken as raw materials, a combined double-excitation system based on calcined sulfate and carbide slag is adopted, and an organic-inorganic composite technology is combined, so that the problems that the existing self-leveling mortar is difficult to consider early strength and slurry viscosity, and the early strength and the slurry viscosity are poor due to contradiction between an exciting agent and a water reducing agent can be effectively solved. On the basis of ensuring the working performance of the slurry, the early-stage, middle-stage and later-stage mechanical strength and waterproof performance are effectively considered; and high value-added resource utilization of various industrial solid wastes can be realized, and the method has remarkable economic and environmental benefits.

This invention provides anhydrous gypsum-polypropylene composite hollow board and its preparation method. The anhydrous gypsum-polypropylene composite hollow board comprises the following components by weight percentage: 30%-65% modified anhydrous gypsum powder, 30%-65% polypropylene resin, 1%-3% compatibilizer, 1%-3% lubricant, and 0.1%-0.3% antioxidant. The modified anhydrous gypsum powder is prepared by modifying hydroxylated anhydrous gypsum powder with a composite surface modifier formed by compounding long-chain fatty acids or their derivatives with a coupling agent. The anhydrous gypsum-polypropylene composite hollow board is prepared by a two-step method: first, a high-filler functional masterbatch is prepared, and then the hollow board is extruded. By modifying the anhydrous gypsum powder and combining it with the two-step preparation method, the problems of weak interfacial bonding between anhydrous gypsum and the polypropylene matrix and poor dispersibility with high filler content are solved, thus systematically improving the mechanical properties and processing performance of the composite hollow board.

This invention relates to the field of high-efficiency expansive agent technology, and in particular to a slow-release high-efficiency expansive agent for concrete, its preparation method, and its application. The method includes the following steps: crushing limestone, bauxite, hematite, gypsum dihydrate, magnesite, and silica, then ball-milling and sieving to obtain a mixed raw material powder; heating to 650-850℃ and holding for 20-40 minutes, then raising the temperature to 950-1200℃ and holding for 30-60 minutes, continuing to raise the temperature to 1250-1300℃ and holding for 40-70 minutes, and finally cooling to 150-200℃ to obtain clinker; mixing the clinker powder with anhydrite until uniform, adding admixtures and a hydration regulator / activator, and grinding; adding a slow-release coating agent via high-pressure atomization spray, and stirring to obtain a fine mixed powder; mixing and aging in a homogenization chamber to obtain the slow-release high-efficiency expansive agent. The slow-release high-efficiency expansive agent of the present invention gradually generates calcium hydroxide and ettringite crystals to provide efficient compensation when the cement hardened body begins to shrink, and achieves continuous micro-expansion throughout the process by relying on later expansion sources such as periclase.

The invention relates to a coal gangue micro-expansion sealing material as well as a preparation method and application thereof, and belongs to the technical field of filling materials. The coal gangue micro-expansion sealing material provided by the invention comprises the following raw materials in parts by weight: 550-650 parts of coal gangue micro powder; 270 to 290 parts of sulphoaluminate cement; 65 to 75 parts of an ettringite expanding agent; 7-9 parts of redispersible latex powder; 1.5 to 2.5 parts of hydroxypropyl methyl cellulose; 2.5 to 3.5 parts of a silane coupling agent; 3.5 to 4.5 parts of polypropylene cellulose; and 28-38 parts of gypsum powder. A large amount of coal gangue is used as a main raw material, the solid waste utilization rate is up to 60%, dependence on natural resources is reduced, and environmental pollution is reduced; and meanwhile, the production cost is reduced by 20%-30% compared with that of a traditional sealing material, and good economic benefits are achieved.

The invention relates to a method for preparing II-type anhydrous gypsum by regulating phosphogypsum, which comprises the following steps: S1, stirring concentrated sulfuric acid and water while mixing to obtain a sulfuric acid solution; s2, directly adding an ardealite raw material into the sulfuric acid solution obtained in S1 to obtain ardealite slurry, and controlling a reaction system to be in a temperature range of 70-90 DEG C for conversion reaction; and S3, carrying out solid-liquid separation on the mixture after the reaction in the step S2 is finished, washing the obtained solid product, and drying to obtain the type II anhydrous gypsum. The method has the advantages that dilution heat released in the concentrated sulfuric acid dilution process is used for providing a main heat source for the system, energy consumption of external heating equipment can be reduced, the defect of huge energy consumption of a traditional high-temperature calcination method is overcome, and economical efficiency and environmental friendliness are achieved. Meanwhile, active regulation and control on the crystallization process of the anhydrous gypsum are realized by accurately controlling reaction conditions, and a micron-sized crystal product with regular crystal form and uniform and coarse particle size is successfully prepared.

The application belongs to the technical field of special cement, and relates to a gypsum-based calcination-free sulphoaluminate cement and a preparation method thereof. In order to solve the problems of high energy consumption and high pollution in calcining clinker for producing sulphoaluminate cement, and the problems of recycling and high-quality utilization of multiple solid wastes, the gypsum-based calcination-free sulphoaluminate cement comprises building gypsum, anhydrite, silica fume, ultra-fine fly ash, cement, carbide slag, zeolite powder, expanded perlite attached microbial powder, aluminum sulfate, melamine, borax, sodium citrate and polycarboxylic acid high-performance water reducing agent. Through reasonable matching of the melamine, the borax and the sodium citrate, effective nutrient components are provided for the microorganisms, the breeding and excretion of the microorganisms are promoted, and then the self-repairing property and the comprehensive performance of the calcination-free sulphoaluminate cement are improved. Through optimization combination of multiple-component solid waste powders, the normal hydration and strength growth of the calcination-free sulphoaluminate cement are realized by introducing the enhanced excitation components and the microorganisms.

The invention discloses a ceramic tile adhesive taking alpha-two-phase gypsum as a main cementing material and a preparation method thereof, the ceramic tile adhesive comprises alpha-two-phase gypsum, a composite water reducer and dihydrate gypsum, the alpha-two-phase gypsum comprises 35-65% of alpha-semi-hydrated gypsum and 65-35% of alpha-anhydrite II; the adding proportion of the composite water reducing agent is 0.01%-0.2% of the mass of the alpha-two-phase gypsum, and the composite water reducing agent is prepared from lignosulfonate and melamine according to the mass ratio of (1-2): 1. The adding proportion of the dihydrate gypsum is 0.5%-1.0% of the mass of the alpha-two-phase gypsum. The preparation method comprises the following steps: uniformly mixing all the preparation material components, adding water according to the standard consistency, and stirring to form jelly for use. The gypsum-based ceramic tile adhesive with alpha-two-phase gypsum as the main cementing material is free of organic rubber powder, free of dry shrinkage, few in variety of auxiliary materials in the formula, simple to prepare and high in adhesive force to ceramic tiles, is used for smooth surfaces of the ceramic tiles and even has good adhesive force on glass surfaces, meanwhile, can quickly generate adhesive strength, is controllable in setting time, and can be used for preparing the ceramic tiles. The maintenance period is short, and the construction period is greatly shortened.

The invention discloses slag-sulphoaluminate compound gelled seawater and sea sand mortar and a preparation method thereof, and relates to the technical field of building materials. Comprising the following component raw materials: 180-220 parts of functional aggregate; 100 parts of a cementing material; 40 to 50 parts of a functional mixing liquid; the functionalized aggregate is sea sand loaded with a nanocrystalline seed layer on the surface; the cementing material is prepared from granulated blast furnace slag powder, natural anhydrite and high belite sulphoaluminate cement clinker; the functionalized mixing liquid is seawater or artificial seawater dissolved with a composite thixotropic-flocculating agent. According to the scheme, the core problems of low strength and poor durability caused by interface looseness and erosion medium permeation of the seawater and sea sand concrete are solved; and full resource utilization of the seawater, the sea sand and the slag is realized, and high performance, high durability and remarkable economic benefits are achieved.

A method of manufacturing a fertilizer comprising biomass, consists in that the biomass comprising, in dry matter, simple and complex proteins in an amount from 8 to 30% by weight and phosphorus compounds in an amount from 1 to 3% by weight P2O5, is mixed with at least one carbonaceous raw material selected from the group comprising lignite, bark, sawdust, humus, compost, peat and straw in an amount of 5 to 20% by weight in relation to the biomass, is ground to a particle size of less than 5 mm to produce a pulp with a dry matter content from 10 to 70%, then the resulting pulp is mixed with at least one evaporite mineral selected from the group comprising polyhalite, calcite, dolomite, gypsum, anhydrite, carnallite, sylvite, barite, after which the whole is dehydrated to a dry matter content from 40 to 85%, then mixed with alkaline raw materials in an amount sufficient to control the temperature of the mixture in the range from 60 to 140ºC and obtain a moisture content of less than 30%, preferably 10 to 15%, and then the product obtained is granulated to obtain granules with sizes from 1 to 5 mm, and alkaline raw materials forming inorganic coatings are applied to the surface of the granules, after which a substance forming an outer coating is sprayed.

The invention discloses a modified anhydrite cementing material based on mechanochemical induced lattice distortion, a preparation method and application thereof, and self-leveling mortar, and belongs to the technical field of building materials and solid waste resource utilization. The modified anhydrite cementing material is prepared by mixing type II anhydrous anhydrite powder with a lattice distortion activator, a synergistic activator, a hydrophobic modifier and an acid-base regulator and then carrying out mechanical grinding and activation. The obtained modified anhydrite cementing material is low in hydration energy barrier, high in activity and good in dispersity and has extremely high hydration activity and excellent water resistance when being used in self-leveling mortar, the 24-hour compressive strength is larger than or equal to 6.5 MPa, the 28-day compressive strength is larger than or equal to 35 MPa, the softening coefficient can reach 0.85 or above, and the problems that industrial byproduct anhydrite is low in early strength, poor in water resistance and prone to saltpetering are effectively solved.

The invention discloses a grouting material for rapid repair of a coal mine tunnel and a preparation process of the grouting material. The grouting material comprises a material A, a material B and water, the material A comprises sulphoaluminate cement clinker, metakaolin, a retarder and a defoaming agent; the material B comprises anhydrite, slaked lime, an alkaline activator, a defoaming agent, calcium nitrite, a rheological agent and a water reducing agent, and the technical problems that a traditional CSA material is insufficient in early strength, poor in fluidity and reduced in later strength are solved by doping the modified admixture and the mineral admixture.

The application relates to a system for preparing valuable products by sectional fluid roasting of gypsum and a method thereof, and belongs to the field of comprehensive utilization of gypsum. The system comprises a feeding-dedusting system, a first roasting system, a second roasting system and a gas-solid separation-treatment system; the feeding-dedusting system, the first roasting system, the second roasting system and the gas-solid separation-treatment system are sequentially connected. The system is suitable for three different processes of gypsum -> beta-hemihydrate gypsum -> anhydrite, gypsum -> anhydrite -> calcium oxide + sulfur dioxide and gypsum -> anhydrite -> calcium sulfide by roasting different gases. Compared with traditional rotary kiln and shaft furnace roasting, the system realizes efficient mass and heat transfer of gas and solid. In the roasting process, sectional roasting technology is adopted, the roasting atmosphere (air, coal gas and hydrogen), the gas amount and the roasting temperature of the second roasting system are finely controlled, and the phase transformation of gypsum is accurately controlled. Compared with other roasting furnaces, the system has the advantages of low energy consumption, small floor area and high running rate.

The invention discloses an activation method of anhydrite II and a gypsum product. The activation method comprises the following steps: mixing anhydrite II with alpha-type semi-hydrated gypsum and a composite activator to obtain a mixture; wherein the alpha-type semi-hydrated gypsum is used as an activation activator and an early curing agent of the anhydrite II, and the composite activator is prepared from superfine slag powder and sodium sulfate; adding water into the mixture, and stirring to form slurry; pouring and forming the slurry to obtain a pouring body; the pouring body is maintained; and drying treatment is carried out after curing is finished. According to the activation method of the anhydrite II provided by the invention, the alpha-type semi-hydrated gypsum is used as the activation activator and the early curing agent, and the superfine slag powder and the sodium sulfate are used as the composite activator, so that the drying strength and the softening coefficient of the activated anhydrite II can be improved, the setting time of the anhydrite II is stable, and the hardening volume of the anhydrite II is still kept in the micro-expansion anhydrite II.

This application relates to the field of phosphogypsum modification technology, specifically disclosing a method for improving the strength and softening coefficient of building β-phosphogypsum products. This method enhances the strength and softening coefficient of building β-phosphogypsum products by adding water-reducing agents, active Al2O3 minerals, blast furnace slag or first-grade fly ash, micro-expansion additives, and organic polymer materials to β-phosphogypsum. The active Al2O3 minerals react with gypsum to generate ettringite and aluminum hydroxide gel, reconstructing the gypsum matrix at the microstructure. The significant reduction in porosity provides the prerequisite for the organic polymer materials to form a continuous and complete waterproof membrane. This makes it less likely for the waterproof membrane formed by polystyrene powder to break due to voids, preventing water intrusion and thus compromising the overall water resistance. This significantly improves the strength and water resistance of β-phosphogypsum composite cementitious materials, solving the problems of low strength and poor water resistance of existing β-type industrial by-product gypsum.

The invention discloses a method and a system for producing anhydrite IIe by using industrial byproduct gypsum based on an autoclave mode. The method comprises the following steps: mixing powdery industrial byproduct gypsum with a composite dehydrating agent, preheating, feeding the preheated material into a reaction kettle, and carrying out two-stage static autoclave on the material at 195-200 DEG C in a mode of combining introducing superheated steam into the kettle and introducing saturated steam into a steam coil on a shell of the kettle, so as to generate wet anhydrite IIe; then superheated steam is introduced to enable the wet anhydrite IIe in the reaction kettle to be in a boiling state, and after stirring is started, the materials are dried under the conditions of normal pressure, continuous stirring and external saturated steam heating. According to the method, the anhydrite IIe is generated by effectively utilizing low-temperature steam of a thermal power plant by utilizing the combined action of saturated steam and superheated steam and combining with a unique process of staged static autoclaving.