9 results about "Chromite" patented technology

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 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 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.

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.

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 discloses a process for the smelting and reuse of neutral slag from high-carbon ferrochrome smelting, belonging to the field of ferroalloy metallurgical technology. This process addresses the challenge of residual recovery from neutral slag in high-carbon ferrochrome smelting by utilizing a core-shell nanocomposite modifier and a gradient magnetic field to achieve integrated slag pre-reduction, modification, and smelting reuse. Using neutral slag, ferrochrome concentrate, carbonaceous reducing agent, and core-shell modifier as raw materials, the mixture is dry-loaded and pre-reduced in a gradient magnetic field rotary kiln, followed by deep melting in a hot-charged submerged arc furnace. Basicity is controlled, and the nano-agent catalyzes the dissolution of Cr2O3 and induces oxygen vacancy network disruption, promoting slag-iron separation. Compared to traditional methods, this process improves recovery rate, reduces energy consumption, produces uniformly dispersed carbides without macroscopic inclusions, and achieves efficient reuse of neutral slag in an economical and environmentally friendly manner.

The application provides high-carbon ferrochrome and a smelting method thereof. In the method, chromite powder, coke powder and coal pitch are uniformly mixed to prepare a binding mixture, the binding mixture is pyrolyzed and sintered, and then is fed into an electric furnace together with a reducing agent and a slag forming agent to be smelted to be clean, and then is refined by top and bottom combined blowing of a converter, is slagged, and is cast to obtain high-carbon ferrochrome. The method smelts high-carbon ferrochrome by sintering, in-furnace smelting and blowing, and can not only obtain high-quality products, but also effectively reduces power consumption compared with traditional complete in-furnace smelting, because no power is supplied in the blowing process, and almost no power is consumed. The high-carbon ferrochrome has low impurity content of sulfur and phosphorus, and has the characteristics of small amount of inclusions and high alloy purity, because the high-carbon ferrochrome has experienced multiple purification steps of pyrolysis, sintering and converter blowing.

An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr2O4 (for example manganochromite); from 15 to 25 wt. % of Cr0.23Mn0.08Ni0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr1.3Fe0.7O3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr2O3 (for example eskolaite); from 4 to 20 wt. % of CuFe5O8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.