42 results about "Chromite" patented technology

The invention belongs to the field of comprehensive utilization of chromite, and particularly relates to a method for producing high-carbon ferrochrome through chromite pellet prereduction-electric furnace smelting. According to the method, a reduction method that a reducing agent and chromite pellets are fed into a kiln separately is adopted, chromite oxidized pellets are prepared firstly and then reduced through a rotary kiln solid carbon reducing agent, and the obtained pre-reduced pellets are subjected to electric furnace smelting with a calcium flux and a magnesium flux as slagging fluxes to prepare the high-carbon ferro-chrome. The problem that according to an existing method, the metallization rate of the pre-reduced pellets and the adverse effect on electric furnace smelting caused by unstable carbon residues are solved, the production stability of the electric furnace can be improved, and meanwhile the electric furnace smelting temperature can be increased. The method is simple, controllable, low in energy consumption, high in efficiency, high in stability, low in production cost and convenient for industrial application.

This invention relates to the field of casting technology for sand cores and sand shells, and particularly to a method for preparing high-precision casting sand cores and sand shell components based on a coated sand process. The method includes the following steps: rinsing quartz sand and reacting it with a sodium silicate solution to obtain coated quartz sand; adding 3-aminopropyltriethoxysilane and water to the coated quartz sand in a high-speed mixer; sequentially adding modified benzoxazine resin, calcium citrate, magnesium chloride, hyperbranched polyamide, and polycaprolactone-grafted starch to obtain finished coated sand; plasma-treated chromium-12 molybdenum-vanadium mold steel to obtain an amino-modified mold; sand-jetting the finished coated sand into left / right half-shells; shaping and pre-embedding chromite sand cores with chills to obtain left / right half-shell green blanks; milling the surfaces of the left / right half-shell green blanks, coating them with resin, butt-jointing, curing, and deburring to obtain the casting sand core and sand shell. This method solves the problems of poor mechanical strength, poor high-temperature stability, low production efficiency, and poor environmental performance in high-precision casting sand cores and sand shells.

The present invention provides a heat exchanger capable of stably and continuously recovering heat over a long period of time, even when the target gas for heat recovery is an extremely corrosive gas, and an exhaust gas treatment device using such a heat exchanger. [Solution] The heat exchanger of the present invention is characterized by comprising a partition plate (14) made of refractory castable material that divides the inside of the casing (12) so that the low-temperature side fluid (LF) and the high-temperature side fluid (HF) flow in countercurrents, and a plurality of solid heat transfer rods (16) made of at least one ceramic selected from the group consisting of alumina, zirconia, silicon carbide, silicon nitride, molybdenum silicide, and lanthanum chromite, which are arranged to airtightly penetrate the front and back surfaces of the partition plate (14) and cross the flow paths of the low-temperature side fluid (LF) and the high-temperature side fluid (HF).

The utility model discloses a chromite oxidizing roasting device, which belongs to the technical field of metallurgical chemical equipment and comprises a first-section heating kiln, a second-section deep oxidation kiln, a chute and a support frame, the first-section heating kiln, the second-section deep oxidation kiln, the chute and the support frame are distributed in an up-and-down stepped manner, and the kiln heads of the first-section heating kiln and the second-section deep oxidation kiln are lower than the kiln tails and are inclined. According to the utility model, the sectional deep oxidizing roasting device is used for sectional oxidizing roasting, and the first-section heating kiln is mainly used for preheating raw materials and carrying out preliminary oxidizing roasting in the heating process; the second-section deep oxidation kiln is connected into an oxygen introducing pipeline, high-concentration oxygen gas is introduced into the kiln body, and deep oxidation roasting is carried out; meanwhile, when the oxygen hole is controlled to rotate to the bottom of the material, the controller opens the oxygen control valve of the corresponding access point, the material is exploded by means of the gas pressure of the oxygen, the contact area of the material and the oxygen is further increased along with rotation of the kiln body, and the mass and heat transfer effect is enhanced. The deep oxidation roasting device improves the chromium conversion rate, reduces the production cost and reduces the environmental pollution.

The invention relates to a sample pretreatment method for chromite microelement analysis. The method comprises the following steps: firstly, treating a sample to specific particle size distribution (Dv (50) lt, 5 [mu] m, Dv (90) lt, 20 [mu] m) through physical accurate grinding, and then adopting an improved two-step acid dissolution and digestion process: firstly, destroying main crystal lattices of minerals by using mixed acid, then, carrying out targeted dissolution on a residual insoluble phase by using aqua regia, and finally, carrying out chlorine removal treatment to obtain a solution to be detected. Through the synergistic effect of physical accurate grinding and secondary acid dissolution, almost complete decomposition of chromite is achieved, especially the extraction efficiency of key indissolvable elements such as Sc and Zn is improved by 20% or above, the accuracy and precision of ICP-MS analysis results are remarkably improved, and the problem that microelement measured value systematicness is low due to incomplete dissolution in a traditional method is solved.

The invention discloses an investment casting shell-making process of a stainless steel part, which comprises the following steps of: dipping a layer of slurry on the surface of a module, spraying a layer of sand on the surface of the module, performing high-temperature dewaxing after five layers are reached to form a shell, filling a mixture of chromite sand and water glass in an inner hole of the shell, and introducing carbon dioxide gas, so that an inner hole sand mold is quickly hardened; and roasting the treated shell, and carrying out vacuum pouring, cooling molding, cutting and polishing treatment on the shell to obtain a casting. The inner hole of the shell is filled with the mixture of the chromite sand and the water glass, the carbon dioxide is introduced into the inner hole to react with the water glass, and finally generated silicic acid gel enables the sand mold at the inner hole to be rapidly hardened, so that the problem that the plane of the shell is expanded due to expansion generated by wax melting in the dewaxing process is solved; and meanwhile, the chromite sand has the characteristic of rapid heat dissipation and is used as an internal chilling block, so that the problem of shrinkage porosity of the shell caused by slow heat dissipation of the bottom plane of the inner hole in the pouring process is solved.

The invention discloses a casting method for prolonging the service life of a metallurgical slag pot, and relates to the technical field of metallurgical casting. According to the method, the material ratio is optimized, and low-alloy heat-resistant steel containing Cr, Ni, Mo, V and Ti is adopted as a matrix; the casting process is optimized, quartz sand and chromite sand composite sand is adopted, lost foam casting and stepped cooling are adopted, and casting defects are reduced; through quenching and tempering heat treatment and Al2O3-TiO2 ceramic coating surface strengthening, the high-temperature erosion resistance, corrosion resistance and thermal shock resistance of the slag ladle are improved. The prepared slag ladle is complete in structure and stable in performance, the service life is prolonged to 1500 heats or above and is improved by 60% or above compared with the prior art, the technology is mature and controllable, the slag ladle is suitable for industrial batch production, the production cost of metallurgical enterprises can be effectively reduced, and the slag ladle has important industrial application value.

This invention relates to a manufacturing method for large ball valve castings for pumped storage power stations, belonging to the field of large-scale high-end cast steel parts manufacturing technology. It solves the problems of shrinkage porosity, cracks, inclusions, and uneven mechanical properties that easily occur inside large valve castings in existing technologies. The method includes: a smelting step: smelting molten steel using an electric furnace, LF furnace, and VD vacuum treatment while controlling the carbon equivalent; a casting step: using a composite mold and chromite sand, baking and argon protection of the mold cavity, and employing a stepped casting process of converting from a double-gate to a single-gate and then point-to-point replenishment; and a heat treatment step: sequentially performing pretreatment and a water-cooling-air-cooling-water-air-cooling-water-air-cooling process followed by high-temperature tempering. This method achieves high-quality, high-density, high-performance, and stable manufacturing of large ball valve castings for pumped storage power stations.

The invention relates to the technical field of refractory materials, in particular to a magnesium-chromium refractory material containing magnesia and chromite and a preparation method of the magnesium-chromium refractory material. The magnesium-chromium refractory material comprises chromite particles, magnesia fine powder, modified magnesium oxide, phenolic resin powder, sodium tripolyphosphate and magnesium stearate. Phosphate radical groups grafted on the surface of modified silicon dioxide adsorb and complex Cr < 3 + > / Al < 3 + > metal ions in advance and are gradually released along with the increase of the pH value of a system in the synchronous dropwise adding process of alkali liquor, so that the metal ions realize controlled and uniform coprecipitation on the surface of the modified LDH nanosheet, and a gradient spinel coating layer with uniform thickness and continuous crystal lattices is constructed on the surface of magnesia in situ. Cr < 3 + > / Al < 3 + > synergistic deposition is adopted, so that the thermal shock resistance is greatly improved. Silicate radicals in the modified LDH generate magnesium aluminum silicate in situ during high-temperature calcination, and interface chemical connection is achieved.

This invention discloses a glass bottle formulation comprising the following raw materials: 100-120 parts silica sand, 30-45 parts soda ash, 8-12 parts dolomite, 8-12 parts calcite, 7-9 parts fluorite, 1-1.5 parts mirabilite, 2.5-3.5 parts environmentally friendly glass kiln ash, 3.5-7 parts SiC whisker / mullite whisker / nano TiO₂ composite, 0.8-1.2 parts sodium nitrate, 1-3 parts chromite powder, and 500-600 parts green waste glass slag. The beneficial effects of this invention are: a high proportion of green waste glass slag significantly reduces the consumption of raw materials such as silica sand and soda ash; it achieves the resource utilization of industrial solid waste, reducing solid waste disposal costs and carbon emissions; the sodium sulfate and calcium silicate particles in the environmentally friendly ash synergistically aid melting, reducing melting energy consumption; and the whisker composite, through the synergistic effects of SiC whisker stress dispersion, mullite whisker framework filling, and nano TiO₂ bubble adsorption, improves the impact resistance of beer glass bottles.

The invention relates to the field of ferrochrome smelting, in particular to a reinforced chromite pellet consolidation additive and a use method thereof, the method comprises the following steps: (1) adding a boron-containing substance into a chromite pellet mixture according to a required proportion, fully and uniformly mixing, and pelletizing the uniformly mixed ore to obtain chromite pellets; the boron-containing substance is selected from at least one of borax, boric sludge and the like; the ratio of boron-containing substances in the chromite pellets is 0.1 to 5 weight percent; and (2) drying, preheating and roasting the green pellets to obtain the chromite pellets. The borax, the boric sludge and the like are adopted as raw materials, the raw materials are wide in source and low in cost, meanwhile, the boric sludge is recycled, and solid waste cyclic utilization is achieved on the premise that iron removal treatment is not needed. And a product prepared from the furnace burden has good mechanical strength and relatively high quality. The problems of high temperature, low furnace charge mechanical strength and the like in the chromite furnace charge preparation heat treatment process are solved, and the production operation of an electric furnace is stabilized.

The invention is used in the construction of the roof of a building and instead of a unilith or ceramic block in a beam ceiling, a block (concrete or metal, chromite or composite) is used. In such a way that first the block is filled with compressed air through its nozzle, then it is placed between the beams instead of the unilith block and it has a seat on the beam. Its placement is simple and does not require special expertise, and the foundation and jacks required are exactly the same as for a beam ceiling with other blocks. After pouring concrete from under the roof, the air inside the block is first evacuated through the existing groove by applying physical pressure or a suction pump, and then it is removed from the roof by grabbing its handles and can be used for the next roof. The reuse process can be repeated for up to 10 roofs or more. It should be noted that (apart from the type of block, such as Unolite or clay, etc.), the block in the beam roof does not perform any structural work and is used only to hold concrete and temporary loads during construction. After the concrete sets, it is no longer effective and can be evacuated. Therefore, considering this and the possibility of renting this invention, the final price is greatly reduced (up to one twentieth of the price of Unolite).

The present application relates to the technical field of iron smelting, and particularly relates to a high-carbon chromite hot furnace slag iron separation optimization method. The content comprises the following steps: obtaining the temperature of molten iron and the temperature of furnace slag, respectively estimating the instantaneous density values of the molten iron and the furnace slag, and obtaining the density ratio of the molten iron and the furnace slag; based on the density ratio of the molten iron and the furnace slag, constructing an interface height dynamic positioning model to obtain the layered interface height; introducing a layered shear disturbance intensity calculation formula to quantize the shear force and obtain the shear disturbance intensity; based on the shear disturbance intensity, combining the layered interface height, adjusting the molten iron furnace slag outlet opening ratio, and performing separation optimization based on the molten iron furnace slag outlet opening ratio. The technical problem that in the process of slag separation, mainly relying on the experience of operators and fixed structure adjustment, unable to realize the dynamic response control of the layered interface height, and easily affected by interface disturbance, temperature gradient and other factors to cause the technical problems of layered failure and frequent mixed flow phenomenon are solved.

The invention relates to a slagging method for producing high-carbon ferrochrome through high-temperature smelting of chromite. Calcium, magnesium and siliceous fluxes are adopted as slagging fluxes, the adding amount of a reducing agent is determined according to the theoretical carbon addition amount of ferrochrome oxide reduction, and the adding amount of each slagging flux is determined on the basis, so that the mass ratio of SiO2 to Al2O3 in the final smelting slag composition is (1.0-2.0): 1, the mass ratio of (CaO + MgO) to Al2O3 is (1.0-1.5): 1, and the mass ratio of CaO to MgO is (0.2-0.5): 1. Smelting is conducted in high-temperature smelting equipment according to the slagging method, the smelting temperature ranges from 1600 DEG C to 1700 DEG C, and after slag and alloy are separated, the high-carbon ferrochrome alloy is obtained. The slagging method is used for high-carbon ferrochrome smelting, the smelting temperature is reduced, the slag amount and carbon emission are reduced, the recovery rate of the chromium element is increased, the production cost is reduced, and obvious economic benefits and environmental benefits are achieved.

The invention discloses a low-silicon low-titanium high-carbon ferro-chrome product and a smelting and casting method, and belongs to the technical field of high-carbon ferro-chrome processing, and the low-silicon low-titanium high-carbon ferro-chrome product comprises the following components in percentage by mass: 48-55% of Cr, 6.0-9.0% of C, and 1t of Si; 4%, Ti: lt; 0.01%, V: lt; 0.02%, Al: 1t; 0.10%, S < = 0.02%, and P < = 0.02%; and the balance of Fe and inevitable impurities. The smelting and casting method comprises the following steps: S1, grinding chromite, and uniformly mixing A; s2, mixing and agglomerating the material A and a binder, and carrying out chain grate-brick kiln consolidation roasting to obtain chromite pellets; s3, the chromite pellets are put into a submerged arc furnace, melting reduction is conducted in combination with a flux and a reducing agent, and high-carbon ferrochrome alloy liquid with the components reaching the standard is obtained; and S4, under the totally-closed Ar-H reductive protective atmosphere, the alloy liquid is injected into a fire-resistant crystallizer with a built-in partition plate and a bottom ejection mechanism. According to the method, the impurity removal efficiency is improved, and industrial-grade production for stably controlling the titanium content in the high-carbon ferrochrome is realized.

A vacuum pump comprising a stator (2) and two rotors received in at least one pumping chamber of the stator (2), the rotors being configured to rotate in the pumping chamber to drive a gas to be pumped between a suction port (4) and a discharge port (5) of the vacuum pump, characterized in that the stator (2) comprises at least one stator piece obtained by casting iron or steel in a mold receiving at least one sand core comprising a majority of sand selected from one or more of the following sands: artificial globular ceramic sand, chromite sand, bauxite sand, zircon sand, kerphalite sand, olivine sand, the surfaces of the cast stator piece (2) intended to be exposed to the pumped gases being coated. Figure 1

A method of making an Fe—Cr electrolyte includes a) oxidizing a carbon-containing Fe—Cr alloy with Fe2O3 or FeO; and b) treating the oxidized carbon-containing Fe—Cr alloy with FeCl3 or HCl or any combination thereof to produce a FeCl2—CrCl3 electrolyte. The method may also include treating, under reducing conditions, a starting material, such as chromite ore, with a carbon source to produce the carbon-containing Fe—Cr alloy. Additionally or alternatively, the method may include removing a portion of the FeCl2 from the FeCl2—CrCl3 electrolyte to obtain a selected iron to chromium molar ratio for the Fe—Cr electrolyte.

The application provides a method for recovering chromite, and relates to the field of mineral processing. The method for recovering chromite comprises the following steps: first crushing chromite raw ore to obtain a first crushing product; first screening the first crushing product to obtain a first screen oversize and a first screen undersize; photoelectric preselection of the first screen oversize to obtain a photoelectric preselection concentrate and a photoelectric preselection tailing; roller pressing treatment of the first screen undersize to obtain a roller pressing product; second screening of the roller pressing product to obtain a second screen undersize, third screening of the second screen undersize to obtain a third screen undersize; desliming treatment of the third screen undersize to obtain fine sludge and coarse-grained gravity separation feed; coarse-grained gravity separation of the coarse-grained gravity separation feed to obtain a first chromite concentrate, a second chromite concentrate and gravity separation fine-grained feed; and grading treatment and fine-grained gravity separation of the gravity separation fine-grained feed to obtain a third chromite concentrate and a tailing. The application can obtain a high-quality chromite concentrate with a high recovery rate.

The application discloses a preparation method of modified high-carbon ferrochrome based on a pre-reduction technology and belongs to the technical field of ferroalloy metallurgy. The method comprises the following steps: uniformly mixing chromite concentrate, coke powder, lime and a silicon dioxide-titanium dioxide nano composite modifier to obtain a mixture; performing solid-state pre-reduction on the mixture in a rotary kiln, and controlling the pre-reduction degree to be 45-70%; loading the pre-reduced material into a submerged-arc furnace, smelting and reducing at 1650-1800 DEG C for 4-8 hours, until slag and iron are separated, and modified high-carbon ferrochrome is obtained. The nano composite modifier is prepared by a sol-gel method, is dispersed at a slag-gold interface during the pre-reduction and smelting processes, promotes uniform nucleation of ferrochrome carbide, and optimizes the microstructure of the molten slag. The application significantly improves the chromium recovery rate, reduces unit power consumption, improves the slag-iron separation effect, and realizes efficient, low-consumption and clean production.

The invention discloses a process for smelting high-carbon ferro-chrome by partially replacing coke with anthracite as a reducing agent, and belongs to the technical field of organic reducing agents. The process comprises the following steps: preparing modified Bi2WO6 and Fe3O4 with a network structure; the modified Bi2WO6, the Fe3O4 with the network structure, anthracite powder, metallurgical coke powder and a binder are subjected to mechanical chemical activation through a ball mill to prepare a composite catalytic reducing agent, and the composite catalytic reducing agent and high-carbon chromite ingredients are fed into an electric furnace to be subjected to reduction smelting at the temperature of 1650-1750 DEG C. Through catalytic synergy, mechanochemical activation, closed pneumatic conveying and annular material distribution, coke is partially replaced by anthracite, the furnace condition stability is improved, reducing agent consumption, energy consumption and carbon emission are reduced, and the chromium recovery rate and the product purity are improved.

A method of making an Fe-Cr electrolyte includes a) oxidizing a carbon- containing Fe-Cr alloy with Fe2O3 or FeO; and b) treating the oxidized carbon-containing Fe-Cr alloy with FeCl3 or HC1 or any combination thereof to produce a FeCl2-CrCl3 electrolyte. The method may also include treating, under reducing conditions, a starting material, such as chromite ore. with a carbon source to produce the carbon-containing Fe-Cr alloy. Additionally or alternatively, the method may include removing a portion of the FeCl2 from the FeCl2-CrCl3 electrolyte to obtain a selected iron to chromium molar ratio for the Fe-Cr electrolyte.

The invention discloses a furnace charge optimization method for improving the smelting efficiency of a chromite electric furnace, and belongs to the field of ferrochrome smelting. According to the method, the flux required by a slag system is split into at least two parts for research and optimization for the first time, so that on the premise of maintaining high strength in the pellet preparation process, electric furnace ore fluctuation caused by separate addition of chromite and the flux is reduced, and the operation control difficulty of the electric furnace is reduced; and the effect of efficiently smelting the high-carbon ferro-chrome at low carbon and low cost is achieved. According to the requirements of the chromite electric furnace smelting flux, part of the flux is added into the chromite pellet preparation process, the strength of the chromite fluxed pellet preheated pellets is effectively improved, the problems that the preheated pellets are low in compressive strength, high in wear rate and the like in the chromite fluxed pellet preparation process are solved, meanwhile, the distribution of electric furnace charge can be obviously optimized, and the production cost is reduced. Electric furnace production operation can be stabilized, and electric furnace energy consumption can be reduced.

This invention discloses a microcrystalline glass, its preparation method, a cover glass, and an electronic device, belonging to the field of new materials. The composition of the microcrystalline glass is as follows (by mass percentage): SiO₂ 60-80%, Al₂O₃ 1-10%, Li₂O 10-18%, ZrO₂ 3-12%, Na₂O 0-5%, CaO 0-4%, P₂O₅ 1-5%, K₂O 0-3%, Cr₂O₃ 0-10%, Fe₂O₃ 0-10%, where Cr₂O₃ and Fe₂O₃ are not both 0 and 1.9wt%≤Cr₂O₃+Fe₂O₃≤10wt%, the crystalline phase contains a crystal phase that produces a gold-like effect. The crystal phase that produces the gold-like effect is chromium trioxide crystal, or iron oxide crystal, or chromite spinel, or chromium trioxide crystal and chromite spinel.

The invention relates to the technical field of submerged arc furnace waste heat recovery and utilization, and discloses a submerged arc furnace stokehole floor mold pouring and iron slag separation waste heat recovery power generation system. Comprising the following modules and components: a pretreatment and system initialization module, a shunting separation and primary heat exchange module, an iron slag deep cooling and sensible heat recovery module, a flue gas gathering heat exchange and power generation module and a tail end closed loop and waste heat secondary utilization module. The pretreatment and system initialization module comprises a chemical water system, a DCS (Distributed Control System), a temperature sensor, a pressure sensor, a flue gas flowmeter, an external circulating fan, a cold air regulating valve and a radiant heat exchange pipeline; the system can effectively recycle waste heat and radiant heat generated in the cooling process of molten iron and iron slag of the chromite heat furnace, efficient recycling of heat energy is achieved, meanwhile, the environment temperature of a production workshop is reduced, and a safe, environment-friendly and fresh-air working environment is provided for production workers.

The invention relates to the technical field of mineral separation, in particular to low-iron chromium ore and a production method thereof.The production method comprises the steps that S1, pretreatment is conducted, specifically, chromite is pretreated to obtain a pre-selected material with the particle size not larger than 10 mm, and the type and content of iron-containing oxide in the pre-selected material are detected; s2, heating reduction is conducted, specifically, the pre-selected material is added into smelting equipment, a carbonaceous reducing agent or a siliceous reducing agent is added, the actual adding amount of the reducing agent is 115%-125% of the theoretical adding amount, and then continuous stirring is conducted for 1-36 h at the temperature of 800-1400 DEG C; s3, separation: raising the temperature to 1400 DEG C or above, preserving heat, precipitating and cooling to obtain elemental iron and low-iron chromium ore; or cooling the product obtained in the previous step, grinding into fine powder, and then carrying out magnetic separation or reselection. The production method provided by the invention not only can reduce the iron content of the chromite, increase the ferrochrome ratio and improve the grade of the chromite, but also is simple to operate, easy to control, high in safety coefficient, low in production cost and beneficial to industrialization.

The invention discloses an iron-based powder metallurgy brake shoe friction body, an iron-based powder metallurgy brake shoe and a preparation method and application of the iron-based powder metallurgy brake shoe friction body and the iron-based powder metallurgy brake shoe, and relates to the technical field of composition brake shoes, and the iron-based powder metallurgy brake shoe friction body comprises, by mass, 60-75% of a matrix component, 3-9% of a reinforcing component, 10-14% of a lubricating component and 12-18% of a friction component; wherein the matrix component comprises iron powder, steel fibers and copper powder, the reinforcing component comprises nickel powder, molybdenum powder and tin powder, the lubricating component comprises graphite and sulfide, and the friction component comprises chromite, aluminum oxide, zirconium oxide and carbide. The iron-based powder metallurgy brake shoe friction body can solve the problems of insufficient braking force, short service life and the like caused by overheating of a wheel tread during high-speed braking of a composition brake shoe.

This invention provides a method for removing hexavalent chromium during high-pressure acid leaching of laterite nickel ore. The method includes the following steps: washing, screening, classifying, beneficiating, and grinding the laterite nickel ore to obtain leaching raw material; separating chromite during beneficiation; mixing high-grade nickel matte slag with the leaching raw material to obtain a compound leaching material; and subjecting the compound leaching material to high-pressure acid leaching to remove hexavalent chromium. This invention provides a method for removing hexavalent chromium from laterite nickel ore during high-pressure acid leaching by separating a portion of chromite through physical beneficiation and then removing Cr(VI) through Fe(II) dissolved in the high-grade nickel matte slag, achieving highly efficient removal of Cr(VI) during the high-pressure leaching reaction.

This invention relates to the field of refractory materials technology, specifically a magnesia-chromium refractory material containing magnesia and chromite, and its preparation method, comprising the following components: chromite particles, fine magnesia powder, modified magnesia, phenolic resin powder, sodium tripolyphosphate, and magnesium stearate. The phosphate groups grafted onto the modified silica surface are pre-adsorbed and complexed with Cr. 3+ / Al 3+ Metal ions are gradually released as the pH of the system increases during the simultaneous dropwise addition of alkali solution, resulting in controlled and uniform co-precipitation of metal ions on the surface of modified LDH nanosheets. This leads to the in-situ construction of a uniformly thick, lattice-continuous gradient spinel coating layer on the magnesia surface. Cr is used... 3+ / Al 3+ Synergistic deposition significantly improves thermal shock resistance. Silicate groups in the modified LDH are converted in situ into magnesium aluminum silicate during high-temperature calcination, achieving interfacial chemical bonding.

The invention relates to the technical field of beneficiation, and discloses a method for realizing comprehensive utilization of ultralow-grade chromite step by step by combining a beneficiation process, which comprises the following steps: S1, crushing and grinding the chromite in raw ore, and carrying out reselection operation to obtain reselected concentrate and reselected tailings; s2, grading operation is conducted on the gravity concentrate, graded concentrate and graded tailings are obtained, and the graded concentrate is chromium concentrate; s3, mixing the graded tailings with the gravity separation tailings, and then carrying out reduction roasting to obtain a roasted product; and S4, the roasted product is subjected to ore grinding and then subjected to low-intensity magnetic separation, low-intensity magnetic concentrate and low-intensity magnetic tailings are obtained, and the low-intensity magnetic concentrate is iron concentrate. According to the method, the gravity separation and classification combined process is adopted, fine-grain high-density chromium can be effectively enriched, the chromium concentrate is obtained, weak-magnetic minerals are converted into strong-magnetic minerals by conducting reduction roasting on tailings, and comprehensive recycling of chromium and iron can be achieved.

The invention provides a low-carbon-content ferrochrome and a production method thereof.The method comprises the steps that raw materials are mixed, specifically, refined chromite and first silicon-chromium alloy are crushed to 1-3 cm respectively and then mixed with lime to be prepared into a mixture; in the smelting process, the second silicon-chromium alloy is laid at the bottom in the smelting furnace, the mixture is added for smelting after power transmission melting, and smelted molten iron is obtained; and casting is conducted, specifically, after smelting is finished, smelted molten iron is transferred into smelting slag containing chromium-containing liquid silicon-chromium alloy, casting is conducted, and a ferrochrome alloy cast ingot is obtained. According to the scheme, carbon is reduced without adopting an oxygen blowing or ladle-to-ladle mode after smelting, so that extra raw material consumption can be controlled on the aspect of production cost, the production efficiency can be effectively ensured, and the defects that the extra production cost is increased and the production efficiency is reduced when the carbon is reduced by adopting the oxygen blowing or ladle-to-ladle mode in the prior art are overcome.