25 results about "Chromium(III) hydroxide" patented technology

The invention relates to the field of vanadium and chromium separation, and particularly discloses a method for removing impurities phosphorus, chromium and silicon in a sodium modified vanadium solution, which comprises the following steps: S100, adjusting the pH value of the sodium modified vanadium solution to enable the pH value of a solution system to be 8.0-9.0 at room temperature to obtain a pretreated sodium modified vanadium solution; s200, heating the pretreated sodium vanadium solution, sequentially adding a reducing agent and a polyelectrolyte into the solution while stirring, and carrying out phosphorus and chromium removal reaction while stirring; s300, after the removal reaction of phosphorus and chromium is carried out for a period of time, adding a silicon removal agent, and carrying out a removal reaction of silicon; and S400, after the silicon removal reaction is finished, standing sedimentation and solid-liquid separation are carried out, impurity-removed slag is washed with water and then merged into the filtrate, and purified vanadium liquid is obtained. According to the method, firstly, glucose is adopted to selectively reduce hexavalent chromium into trivalent chromium under the weakly alkaline condition, pentavalent vanadium is not reduced, the trivalent chromium forms chromium phosphate and chromium hydroxide precipitates in a weakly alkaline solution, and meanwhile, the chromium removal efficiency is improved in a polyelectrolyte coagulation mode.

The application discloses a preparation method of vanadium-doped and high-hydrated mangan-chromian spinel monocrystal under high temperature and high pressure. The cylindrical mangan-chromian spinel sample is prepared by taking solid rose triangular rhombic manganese carbonate crystal, solid chromium (III) acetate hydroxide crystalline powder, solid vanadium (IV) acetylacetonate oxide powder, solid oxalic acid powder, solid bixbyite powder, solid chromium hydroxide powder and liquid dilute nitric acid as starting raw materials; two pieces of water source sheets are made from the bixbyite powder and the chromium hydroxide powder with a weight ratio of 4:1; the two pieces of water source sheets are placed at two ends of the cylindrical mangan-chromian spinel sample and then are placed into a double-capsule structure experimental sample bin with an inner layer sleeve being a graphite tube and an outer layer sleeve being a gold-palladium alloy tube; the high temperature and high pressure reaction is carried out to obtain the mangan-chromian spinel monocrystal; and the preparation technology blank of the vanadium-doped and high-hydrated mangan-chromian spinel large-particle monocrystal under the current high temperature and high pressure conditions is solved.

The application discloses a preparation method of a nickel-doped and high-hydrated cobalt-chromium-iron ore monocrystal under high temperature and high pressure, and the method comprises the following steps: preparing a cylindrical cobalt-chromium-iron ore sample by taking solid basic cobalt carbonate powder, solid chromium (III) acetate hydroxide crystal powder, solid nickel stearate, solid oxalic acid powder, solid chromium hydroxide powder, solid nickel hydroxide powder and liquid dilute nitric acid as starting raw materials; preparing water source sheets by taking chromium hydroxide powder and nickel hydroxide powder in a weight ratio of 4:1; placing two water source sheets at two ends of the cylindrical cobalt-chromium-iron ore sample respectively and then putting them into a double-capsule structure sample bin; and obtaining a cobalt-chromium-iron ore monocrystal after high-temperature and high-pressure reaction, so that the blank of the preparation technology of the nickel-doped and high-hydrated cobalt-chromium-iron ore large-grain monocrystal under the current high-temperature and high-pressure condition is solved, and the experimental sample of the nickel-doped and high-hydrated cobalt-chromium-iron ore large-grain monocrystal is obtained.

The invention discloses a chromium-containing wastewater treatment and recovery treatment line and a recovery treatment method thereof. The ion exchange system is used for carrying out ion exchange adsorption on the hexavalent wastewater; the alkali washing system is used for outputting alkali liquor to the ion exchange system; the washing system is used for outputting washing water to the ion exchange system; the pickling system is used for outputting acid liquor to the ion exchange system; the chromium recovery treatment branch line is used for receiving the hexavalent wastewater of the ion exchange system, mixing the hexavalent wastewater with sulfur powder and alkali liquor to prepare chromium hydroxide, then carrying out filter pressing on the chromium hydroxide, outputting a chromium hydroxide filter cake to the recovery calcination treatment line, and outputting a press filtrate to the press filtrate recovery branch line; the press filtrate recovery branch line is used for recovering sodium thiosulfate from the press filtrate; and the recycling and calcining treatment line is used for calcining the chromium hydroxide filter cake into Cr2O3. According to the scheme, the purposes of micro discharge and even zero discharge of the chromium-containing wastewater are achieved, and the problem that a large amount of chromium-containing hazardous waste sludge is generated by depending on a chemical reduction-precipitation method in traditional chromium-containing wastewater treatment is solved.

The application discloses a preparation method of titanium-doped and high-hydrated magnesio-chromian spinel monocrystal under high temperature and high pressure, and the method comprises the following steps: preparing a cylindrical magnesio-chromian spinel sample by taking solid basic magnesium carbonate powder, solid basic chromium acetate crystal powder, liquid tetraisopropyl titanate, solid oxalic acid powder, solid brucite powder, solid chromium hydroxide powder and liquid dilute nitric acid as starting raw materials; preparing water source sheets by taking brucite powder and chromium hydroxide powder with a weight ratio of 4:1 as water sources; placing two water source sheets at two ends of the cylindrical magnesio-chromian spinel sample and putting them into a double-capsule structure sample bin together to carry out high temperature and high pressure reaction, so as to obtain titanium-doped and high-hydrated magnesio-chromian spinel monocrystal; and the method solves the blank of the preparation technology of the titanium-doped and high-hydrated magnesio-chromian spinel large-grain monocrystal under the current high temperature and high pressure conditions, and obtains experimental samples of the titanium-doped and high-hydrated magnesio-chromian spinel large-grain monocrystal.

The invention discloses a low-chromium-content propane dehydrogenation catalyst and application thereof. The catalyst comprises a composite carrier of aluminum oxide and an MCM-41 molecular sieve, an active component Cr and one or more of auxiliaries Yb, Ga, Sn, Zn and Ba. The preparation method comprises the following steps: preparing the composite carrier by adopting a wet mixing method; the preparation method comprises the following steps: carrying out high-temperature pressurized crystallization precipitation on a precursor of Cr and an auxiliary agent under an alkaline condition to prepare modified chromium hydroxide hydrogel; the hydrogel is washed, dried and crushed, then the hydrogel and the composite carrier are subjected to ultrasonic impregnation in acid liquor, then microwave radiation drying is conducted, and finally the catalyst is obtained through forming, drying, roasting and reduction. The catalyst obviously reduces the chromium content (the Cr loading amount is 1-3% based on the carrier), reduces the environmental pollution and the production cost, has high mechanical strength, high-temperature stability and hydrothermal stability, is used for the propane dehydrogenation reaction, has the propane conversion rate of 48% and the propylene selectivity of more than 95%, has low carbon deposition amount, and is suitable for industrial production. Wide industrial application prospects are shown.

A recovery treatment line and method for chromium-containing wastewater; the recovery treatment line comprises a recovery reactor, a reducing agent feeder, a lye feeder and a recovery filter pressing system; the output end of the recovery reactor is communicated with the recovery filter pressing system, and is used for outputting chromium hydroxide wastewater to the recovery filter pressing system; a primary filter press is used for receiving the chromium hydroxide wastewater of the recovery reactor, and performing filter pressing treatment on the chromium hydroxide wastewater, outputting filtrate to a liquid phase recovery device, and outputting chromium hydroxide to a filter crushing device; the filter crushing device is used for performing crushing treatment on the chromium hydroxide, and outputting the chromium hydroxide to a cleaning tank; the cleaning tank is used for cleaning the chromium hydroxide, and outputting the chromium hydroxide to a secondary filter press; the secondary filter press performs filter pressing treatment on the chromium hydroxide of the cleaning tank, and obtains chromium hydroxide. The scheme solves the problem of high treatment difficulty of chromium-containing wastewater.

The invention relates to a method for recycling iron, chromium and nickel in a waste acid solution, which comprises the following steps: (1) taking the waste acid solution containing + 3-valent iron ions, + 3-valent chromium ions and + 2-valent nickel ions as a reduction end solution, taking a chromium-containing iron acid solution containing + 2-valent iron as an oxidation end solution, carrying out diaphragm electrolysis treatment to obtain a ferrous iron acid solution at the reduction end, oxidizing the end to obtain an iron-chromium solution containing ferric iron; (2) carrying out nickel removal treatment on the ferrous-iron-containing acid liquor through hydrogen sulfide to obtain a nickel sulfide product and nickel-removed liquor; the nickel-removed solution is sequentially subjected to iron-chromium separation and acid dissolution to obtain a chromium-containing iron acid solution containing + 2-valent iron, and the chromium-containing iron acid solution is circulated to the step (1) to be used as an oxidation end solution; and (3) the iron-chromium solution is sequentially subjected to iron removal and chromium precipitation, and a chromium hydroxide product is obtained. Divalent iron and trivalent chromium are separated by utilizing valence change of iron and property difference between divalent iron and trivalent iron; nickel is removed by hydrogen sulfide, so that iron, chromium and nickel in the waste acid solution are completely separated, and no byproduct waste is produced.

The application provides a method for co-extracting vanadium and chromium from high-chromium vanadium slag and application thereof. The method comprises the following steps: roasting high-chromium vanadium slag and calcium salt to obtain roasted clinker, leaching the roasted clinker with a leaching agent to obtain a leaching solution, cooling the leaching solution to obtain sodium orthovanadate and a crystallization mother liquor; adding calcium oxide to the crystallization mother liquor to obtain a chromium-containing solution, performing first reduction on the chromium-containing solution to obtain chromium hydroxide, and performing first calcination on the chromium hydroxide to obtain chromium trioxide; mixing the sodium orthovanadate, water and carbon dioxide to obtain sodium metavanadate, sequentially performing transformation and second reduction on the sodium metavanadate, and performing second calcination to obtain a reduction clinker; mixing the reduction clinker, washing water and sodium bicarbonate mother liquor to obtain a sodium-containing solution and primary vanadium trioxide, and washing the primary vanadium trioxide to obtain vanadium trioxide. The application realizes high-value conversion of high-chromium vanadium slag, and simultaneously considers simplicity and economy, and no high ammonia nitrogen, high salt water and ammonia-containing waste gas are generated.

The present application relates to the technical field of chromium oxide preparation, and particularly relates to a preparation method of chromium oxide. The present application provides a preparation method of chromium oxide, comprising the following steps: after high-temperature leaching of a crude chromium hydroxide leaching solution, solid-liquid separation is performed to obtain a first solid phase and a first liquid phase; the first liquid phase is subjected to extraction to obtain an extraction phase and a raffinate phase; the raffinate phase is mixed with sodium hydroxide to perform chromium precipitation to obtain chromium hydroxide and a first chromium precipitation mother liquor; the chromium hydroxide is subjected to calcination to obtain chromium oxide; an extraction reagent used in the extraction includes an extractant and a diluent; the extractant includes two or more of P507, P204, TOPO, MIBK and TBP; and the diluent includes one or more of sulfonated kerosene, No. 260 solvent oil and isooctanol. The prepared chromium oxide has a main content of >98%, and can reach the smelting metal chromium level.

The invention relates to an aluminum profile production wastewater treatment device which comprises a rack, a treatment barrel is arranged on the rack, a plurality of acid adjusting reduction barrels are arranged on the inner wall of the treatment barrel in a surrounding mode, and a chromium-containing wastewater storage and transportation mechanism and an acid adjusting reduction storage and transportation mechanism are arranged on the treatment barrel and located above the acid adjusting reduction barrels respectively. A first liquid discharging mechanism is arranged on the acid adjusting reduction cylinder; the area of an unreacted area can be reduced when the precipitant is in contact with the trivalent chromium solution, sudden increase of the local PH value of the surface of the trivalent chromium solution can be prevented, convective mixing can be formed after the precipitant is in contact with the trivalent chromium solution, so that the precipitant is in uniform contact with the trivalent chromium solution, and the reaction rate is increased; the method can prevent a chromium hydroxide precipitate layer generated by reaction on the surface of the trivalent chromium solution from hindering diffusion and flow of a subsequent precipitant, and can enable the trivalent chromium solution and the precipitant to uniformly, fully and completely react to generate a chromium hydroxide precipitate.

The application discloses a preparation method of 4N high-purity chromium, and comprises the following steps: step one, adding metal chromium into concentrated sulfuric acid mixed with water for leaching; step two, adopting a Mohr salt method; step three, obtaining a chromium (III) solution through extraction; step four, performing alkaline precipitation on the chromium (III) solution, and obtaining chromium hydroxide through filtration; step five, performing roasting on the chromium hydroxide, and obtaining chromium trioxide; step six, mixing the chromium trioxide with aluminum particles and a heating agent, and sequentially performing vacuum aluminothermic reduction and vacuum suspension smelting to obtain 4N chromium. The preparation method shortens the preparation period under the premise of ensuring the iron removal effect by adopting the process of the Mohr salt method combined with extraction of iron, and effectively reduces the impurity content of gas, iron and the like by adopting the process of vacuum aluminothermic reduction combined with vacuum suspension smelting, so that 4N chromium is obtained, and the method is suitable for the technical field of high-purity metal chromium preparation.

The invention discloses a method for producing an iron-chromium flow battery electrolyte by using an iron-chromium alloy. The method comprises the following steps: preparing an iron-chromium alloy solution, adding reduced iron powder, precipitating chromium ions, removing impurities, filtering, dissolving Cr (OH) 3, and removing impurities from filtrate to obtain a ferrous chloride solution; and preparing the iron-chromium flow battery electrolyte. According to the method for producing the iron-chromium flow battery electrolyte by using the iron-chromium alloy, the iron-chromium alloy reacts with hydrochloric acid, a solution containing iron and chromium is prepared, chromium ions generate chromium hydroxide precipitation separation by adjusting the pH value of the solution, ferric ions generate ferrous ions by adding reduced iron powder, and the iron-chromium flow battery electrolyte is obtained. The preparation method comprises the following steps: adding a chromium hydroxide precipitate into a chromium hydroxide solution, then adding a pure ferrous chloride solution obtained after impurity removal, reacting the chromium hydroxide precipitate with hydrochloric acid to form a pure chromium trichloride solution, and compounding the pure chromium trichloride solution with hydrochloric acid to form the iron-chromium flow battery electrolyte, thereby having the effects of simple process and cost reduction.

The invention belongs to the technical field of inorganic chemical industry, and particularly relates to a method for continuously preparing chromium hydroxide, which comprises the following steps: (1) heating a solution containing Cr < 6 + >, adding a reducing agent and a reducing auxiliary agent, maintaining the pH value of the system at 10-12, and carrying out a reduction reaction to obtain chromium hydroxide slurry; (2) standing and settling the obtained slurry, separating out two parts of chromium hydroxide slurry according to the volume ratio of (1.5-3): 1, and recycling the chromium hydroxide in the step (1) to control the growth of crystal nucleus; and (3) adding sulfuric acid and dilute sulfuric acid into the separated chromium hydroxide slurry step by step, adjusting the pH value of the system to 8-9, filtering, and washing until the pH value of washing water is 6.5-7.5 to obtain a target product. Through optimization of reaction conditions, introduction of the chromium hydroxide slurry and continuous process design, the problems of fine chromium hydroxide particles, high water content, low process efficiency and the like in the prior art are solved, and the method is suitable for the fields of chromium salt production, electroplating wastewater treatment, metal recovery and the like.

The invention relates to a method for selectively and efficiently separating and recovering chromium from vanadium and chromium slag leaching liquid. According to the technical scheme, the method comprises the steps that vanadium and chromium slag sub-molten salt is subjected to alkaline leaching, and vanadium and chromium slag leaching liquid is obtained; and the vanadium and chromium slag leaching solution is put into an evaporation device to be evaporated and concentrated, and the vanadium and chromium slag alkaline leaching concentrated solution is obtained. Putting the vanadium and chromium slag alkaline leaching concentrated solution into a crystallizer, adding a potassium-containing additive into the vanadium and chromium slag alkaline leaching concentrated solution, and carrying out reaction, solid-liquid separation and washing under a first stirring condition to obtain potassium sodium chromate crystals and a post-crystallization solution; dissolving the potassium sodium chromate crystal to obtain a potassium sodium chromate solution, and adjusting the pH value with sulfuric acid; and adding sodium sulfite into the potassium sodium chromate solution, reacting under a second stirring condition, and carrying out solid-liquid separation to obtain a chromium hydroxide solid. And calcining the chromium hydroxide solid to obtain chromium sesquioxide. The method has the characteristics of simple process, low cost, strong adaptability and environmental friendliness, is suitable for the vanadium-chromium-containing solution with high strong alkalinity, and is good in vanadium-chromium separation effect and high in chromium recovery rate.

A method for co-removing chromium and silicon from a sodium-containing vanadium solution by selective reduction. The method comprises: adjusting the pH value of a sodium-containing vanadium solution such that the pH value of the system solution is 10.5-11.5 at 60°C to obtain a pretreated sodium-containing vanadium solution; adding a preset amount of reducing agent to the pretreated sodium-containing vanadium solution at a time for reduction reaction; adding a silicon removal agent to a reaction system at the last stage of the reduction reaction for reaction to obtain a first intermediate reaction solution, carrying out solid-liquid separation on the first intermediate reaction solution, washing a solid phase with water, and then combining the solid phase with a filtrate to obtain an impurity removal solution; and carrying out an oxidation purification treatment on the impurity removal solution to obtain a purified solution. In the present invention, under specific concentration and pH conditions of a sodium-containing solution, vanadium mainly exists in the form of a pyrovanadate, shows relatively low oxidizability and stable properties, and is not prone to reducing. Even if a small part of vanadium is reduced, vanadium still remains as a vanadite in the solution, while a chromate is selectively reduced into chromium hydroxide, thereby completing the separation of vanadium and chromium in the form of a chromium hydroxide precipitate.

The invention discloses a method for preparing a chromic oxide and sodium sulfate solution from chromium-containing sodium hydrogen sulfate, which comprises the following steps: preparing chromium-containing sodium hydrogen sulfate into a sheet by a sheet preparation machine, and calcining to obtain a calcined product; adding the calcined product into water to prepare a feed liquid, then adding sodium hydroxide for neutralization to prepare a mixed solution of chromic hydroxide and sodium sulfate, carrying out heat preservation and curing, then carrying out filter pressing to obtain a filter cake, then washing and carrying out filter pressing on the filter cake to obtain a chromic hydroxide filter cake, and carrying out filter pressing to obtain a filtrate which is a sodium sulfate solution; and calcining the chromium hydroxide filter cake to obtain chromium sesquioxide. According to the resource utilization method for the by-product chromium-containing sodium hydrogen sulfate in the chromic anhydride production process, the chromium-containing sodium hydrogen sulfate is converted into chromium sesquioxide and sodium sulfate solutions with high additional values, the problem of poison of waste is solved, and efficient recycling of chromium and sodium hydrogen sulfate is achieved; in addition, the method is simple in process, low in cost and suitable for industrial production.

The application discloses a method for preparing chromium acetate from chromium hydroxide, which comprises the following steps: mixing chromium hydroxide wet filter cake with sulfonic acid group-chromium oxide composite mesoporous silica balls according to a proportion, adding glacial acetic acid, and then carrying out reaction, heating, separation, concentration crystallization and drying to obtain high-purity chromium acetate. The sulfonic acid group-chromium oxide composite mesoporous silica ball modified material is prepared by the following steps: first, synthesizing a mesoporous silica ball base by using a template agent, then loading chromium oxide and grafting a mercapto group by silanization, and finally oxidizing to obtain a sulfonic acid group functionalized material. The material can selectively adsorb impurity ions in situ in the reaction, so that the traditional complicated purification steps are simplified. The application has the advantages of simple operation, high product purity, and good industrial application prospect.

The invention belongs to the technical field of industrial wastewater treatment and resource recovery, and particularly discloses a multi-metal graded recovery method for vanadium electrolyte wastewater. The method comprises the following steps: adjusting the pH value of the vanadium electrolyte wastewater to 2.0-3.0, adding an oxidizing agent to oxidize ferrous iron into ferric iron, then adjusting the pH value to 4.0-5.0, carrying out iron-aluminum co-precipitation reaction, and carrying out solid-liquid separation to obtain primary filtrate and iron-aluminum slag; adding soluble ammonium salt into the primary filtrate, adjusting the pH value to 8.0-9.0, carrying out vanadium precipitation reaction, and carrying out solid-liquid separation to obtain secondary filtrate and ammonium polyvanadate precipitate; adding a reducing agent into the secondary filtrate to reduce hexavalent chromium into trivalent chromium, then adjusting the pH value to 8.5-9.5, carrying out a chromium precipitation reaction, and carrying out solid-liquid separation to obtain a tertiary filtrate and a chromium hydroxide precipitate; and carrying out deep purification and extraction on the third-stage filtrate to obtain wastewater meeting the discharge standard. According to the method, multiple metals such as vanadium, iron, aluminum and chromium can be recovered from the vanadium electrolyte wastewater in a grading manner, and meanwhile, the wastewater can be discharged up to the standard.

The invention discloses a zero-discharge treatment method and system for steel chromium-containing coating wastewater, and belongs to the technical field of wastewater treatment. Comprising the following steps: S1, introducing the chromium-containing wastewater into an oxidation-reduction device, and converting chromium ions into chromic hydroxide salt precipitate by a reducing agent; s2, introducing the supernatant into a chemical precipitation device, and converting calcium and magnesium ions into precipitates by using a precipitant; s3, introducing the supernatant into a contact oxidation device, carrying out pre-degradation treatment on COD (Chemical Oxygen Demand) by halotolerant bacteria and an antidote, introducing the supernatant into an advanced oxidation device, carrying out oxidative cracking treatment on COD which is difficult to decompose by a strong oxidant, and then introducing the supernatant into a biological filter to carry out biological re-degradation treatment; and S4, pretreating the supernatant, introducing the pretreated supernatant into a membrane concentration decrement device, and treating the concentrated solution through an evaporation device. According to the invention, a plurality of water treatment processes are combined for use, chromium ions, calcium and magnesium ions, organic matters, chloride ions, sulfate ions and the like in the wastewater are separated and removed step by step, and zero discharge of the wastewater is really realized.

This invention provides a method for recovering vanadium, chromium, and sodium from a vanadium-chromium sodium salt solution: (1) Adjusting the pH value of the vanadium-chromium sodium salt solution, adding a chromium precipitation agent and performing a first hydrothermal reaction to obtain chromium hydroxide product and chromium precipitation mother liquor; sequentially performing a first washing and a first heat treatment on the chromium hydroxide product to obtain chromium oxide product; (2) Adjusting the pH value of the chromium precipitation mother liquor, adding a vanadium precipitation agent and performing a second hydrothermal reaction to obtain vanadium dioxide product and vanadium precipitation mother liquor; sequentially performing a second washing and a second heat treatment on the vanadium dioxide product to obtain vanadium pentoxide product; (3) Mixing the first washing residue from step (1), the second washing residue from step (2), and the vanadium precipitation mother liquor, and evaporating and crystallizing the resulting sodium-containing solution to obtain sodium carbonate product. This method avoids the introduction of sulfur and ammonia nitrogen from the source, generates no chromium-containing solid waste, and has a short process, clean process, and low energy consumption.

This invention provides a highly efficient method for separating and recovering iron, nickel, and chromium metal ions from sulfate solid waste, relating to the field of solid waste treatment technology. This invention uses column chromatography to separate sulfate solid waste, effectively separating and recovering iron, chromium, and nickel ions, filling a technological gap in the separation of these three metal ions. Compared to traditional chemical separation methods, this invention is not only simpler and faster with significant results, but also does not use or generate any harmful substances. The only solutions used throughout the process are water and anhydrous ethanol, making it environmentally friendly, extremely low-cost, and easily industrialized. Using the separation and recovery method provided by this invention, the recovery rates of iron, chromium, and nickel are high, all exceeding 96%. Furthermore, after processing the collected liquid according to appropriate methods, the resulting chromium hydroxide, nickel hydroxide, and ferrous oxalate have high purity, all exceeding 97%, and can be used in electrode materials for new energy batteries, demonstrating high resource utilization and good economic benefits.

A nonaqueous electrolyte solution battery lead wire of the present disclosure includes a conductor and an insulating film having one or a plurality of layers and covering at least part of an outer peripheral surface of the conductor. The conductor has a conductor film covering at least part of a surface thereof, the conductor film contains a trivalent chromium compound including chromium hydroxide and a metal element, a ratio of a mass of chromium contained in the chromium hydroxide per unit area [mg / m2] to a mass of chromium contained in the trivalent chromium compound per unit area [mg / m2] is 0.30 to 0.90 at an outermost surface of the conductor film, the insulating film has an innermost layer stacked on a surface of the conductor film, the innermost layer contains, as a main component, a resin component including maleic anhydride-modified polypropylene.

The invention provides a method for removing heavy metals from low-rank coal and preparing potassium humate through thermocatalysis. The method comprises the following steps: mixing the low-rank coal, a reducing agent and water to prepare a reactant A; mixing the reactant A with potassium hydroxide and a catalyst to prepare a reactant B; after the reactant B is naturally cooled to the room temperature, centrifugation, filtration and solid-liquid separation are carried out, and a potassium humate product is obtained.According to the method, hexavalent chromium in the low-rank coal is reduced into trivalent chromium through the reducing agent, follow-up removal is facilitated, a thermocatalytic reaction is carried out under the combined action of air and the catalyst, functional groups of the low-rank coal are enriched, the extraction rate of humic acid is increased, and the yield of the low-rank coal is increased. According to the method, non-fuel high-added-value utilization of the low-rank coal is achieved through a simple and convenient process, the potassium humate product with the high added value is obtained, and the method is an efficient low-consumption mild potassium humate preparation technology; and the method has good economic value and environmental benefit.

The invention provides a method for producing chromium hydroxide by using electroplating sludge. The invention relates to a method for producing chromium hydroxide by using electroplating sludge, which comprises the following steps: (1) slurrying: adding chromium-containing electroplating sludge into a slurrying kettle, adding a certain amount of water, and starting stirring for slurrying; according to the method, the chromium-containing waste liquid and the concentrated sulfuric acid are added into the pulpified electroplating sludge solution for leaching, a proper amount of sodium hypochlorite is added after more than half of the chromium sludge is dissolved, and alkali is added for neutralization after leaching is completed, so that impurity metals such as iron, aluminum, calcium and magnesium in the solution can be removed through a chemical precipitation method; and the follow-up chromium hydroxide preparation process is not interfered by the ions.