The invention discloses a method for preparing sodium chromate by mixing chromite and ferrochrome and a device for the method. The method comprises the following steps: measuring and mixing chromite and ferrochrome with sodium carbonate, sodium nitrate and sodium peroxide; pelleting the mixture with extracted liquid sodium chromate in a pelletizer; drying in a drier; returning part of the clinker to a flame kiln after the material is dried and cooled, so that chromite and ferrochrome are decomposed and oxidized in the form of fused liquid phase in molten salts so as to obtain the clinker of sodium chromate; and continuously soaking, filtering and cleaning after the clinker is cooled so that a chromium chemical primary product of liquid sodium chromate is obtained, wherein the flame kiln comprises a U-shaped kiln body, a partition wall and a low-position molten salt suction port, wherein the partition wall and the low-position molten salt suction port are arranged in the U-shaped kiln body; one or more blowing oxygen lances and one or more charging holes are arranged at the top of the kiln body, and a smoke outlet is arranged on the upper side of the kiln; and one or more oxygen lances are arranged at the bottom of the kiln. According to the method disclosed by the invention, the oxidation rate is as high as 98%, the clinker extraction rate is as high as 99.97%, and the chromium yield is 97.96%.

Method for preparing sodium chromate by mixing chromite and ferrochrome and device for method

The invention provides a preparation method of sodium bichromate. The preparation method comprises the following steps of: (1) adding 700-1,350 g.L sodium chromate neutral solution of a chromium compound in terms of Na2Cr2O7.2H2O into a carbonization reactor; (2) continuously supplying carbon dioxide into the carbonization reactor, and controlling partial pressure of carbon dioxide to be 0.01-1.5 MPa, reaction temperature to be 15-105 DEG C and reaction time to be 0.5-8.0 h; (3) separating carbonized feed liquid obtained by the step (2) to obtain carbonized liquid and sodium bicarbonate crystals, wherein the concentration of the chromium compound in the carbonized liquid is 700-1,350 g.L in terms of Na2Cr2O7.2H2O; and (4) crystallizing and dehydrating the carbonized liquid to obtain the sodium bichromate. By preparing the sodium bichromate through the preparation method, the conversation rate from the sodium chromate to the sodium dichromate can reach 95-100 percent, the quality of the sodium bichromate is high, and the sulfate content is less than 0.1 percent by weight.

Preparation method of sodium bichromate

The invention relates to a method for producing sodium bichromate. The method comprises the following steps: 1) performing hydrothermal oxidation on slurry of chromium-containing sodium carbonate, ferrochromium and soda and water to obtain sodium chromate and carbon dioxide, and removing carbon dioxide; 2) separating the obtained reaction mixture to obtain a sodium chromate solution and iron slag; 3) concentrating the obtained sodium chromate solution to 600-1400g/L; 4) carbonizing and acidizing the sodium chromate concentrated solution by using the carbon dioxide removed in the step 1), thus obtaining a sodium dichromate solution and chromium-containing sodium bicarbonate; and 5) decomposing the obtained chromium-containing sodium bicarbonate into chromium-containing sodium carbonate and carbon dioxide, returning the chromium-containing sodium carbonate to the step 1), and returning carbon dioxide to the step 4). According to the method, the processes of preparing the sodium chromate solution and acidizing the sodium chromate are organically combined, comprehensive recycling of Na+ and CO2 is realized, no waste residues are generated in the whole production process, the discharge of three wastes is greatly reduced, the method is a low-carbon, cyclic and clean type process for production of sodium bichromate, and the purity of the produced sodium bichromate is high.

Method for producing high-quality sodium bichromate

The invention discloses a resourceful treatment method for hazardous wastes containing water soluble salts and organic matters. The method comprises the following steps: 1) carrying out high temperature desorption, and then carrying out water treatment and incineration treatment after low boiling point water and the organic matters obtained by the desorption are subjected to standing and stratification; (2) dissolving and leaching waste residues generated in the high temperature desorption by using fresh water, filtering to obtain a mother liquor and non-water soluble salts and organic matter residues, incinerating the non-water soluble salts and the organic matter residues; (3) using active carbon to carry out absorption and purification on the mother liquor obtained by leaching, incinerating the separated activated carbon, and crystallizing the mother liquor containing salt subjected to refining of the absorption and purification to obtain crystalline mixed inorganic salt, and recycling the mother liquid; (4) testing quality of the obtained crystalline mixed inorganic salt, taking a qualified product as mixed salt for sale; (5) redissolving and recrystallizing the unqualified mixed inorganic salt, and repeating the step (4). The method disclosed by the invention is simple and convenient to operate and good in treatment effect.

Resourceful treatment method for hazardous wastes containing water soluble salts and organic matters

The invention discloses a tubular continuous method for preparing beta-menadione, which comprises the following steps: preparing a beta-methylnaphthalene emulsion, heating the beta-methylnaphthalene emulsion, metering the beta-methylnaphthalene emulsion and an oxidation solution respectively by a measuring pump, adding into a tubular reactor provided with an ultrasonic generator, and carrying out ultrasonic reaction, wherein the retention time of the reactants in the tubular reactor is 1-300 minutes; supplementing dilute sulfuric acid to the outlet of the tubular reactor, adding into a curing tank, and curing for 1-10 hours while keeping the temperature; after finishing curing, filtering, washing, carrying out centrifugal dehydration and drying to obtain the beta-menadione finished product. By using the tubular reactor to produce the beta-menadione, the method has the advantages of high production continuity and short period; and the product has the advantages of high yield, low impurity content and stable quality. The reaction process is easy to control, simple to operate and high in automatic control degree; the material performs forced flow in the tubular reactor to substitute mechanical stirring, thereby implementing industrialized continuous production; and thus, the method has the characteristics of low input cost and short reconstruction period, and can perform large-scale industrial production.

Tubular continuous method for preparing beta-menadione

The invention relates to a molten liquid phase roasting method of chromite. The molten liquid phase roasting method comprises the following step of: performing molten liquid phase roasting on a mixture comprising chromite and optional sodium chromate in a horizontal rotary kiln in the presence of oxygen at 350-1,500 DEG C to obtain sodium chromate, wherein the mixture also comprises one or more of soda, sodium bicarbonate, sodium sulfate and sodium hydroxide; the horizontal rotary kiln comprises a kiln body and two end parts at the two ends of the kiln body; the two end parts are provided with a high-position liquid phase outlet and a low-position liquid phase outlet respectively; the kiln body is provided with an oxygen lance and a feed port; the oxygen lance and the feed port are arranged in a stagger way so as not to be on the same cross section of the kiln body; and a smoke outlet which is positioned on the kiln body is arranged between the high-position liquid phase outlet and one of the feed port and the oxygen lance closer to the high-position liquid phase outlet. According to the method, the chromite is in molten liquid phase in a molten salt system, so that the chromium conversion rate is greatly increased, the yield is increased, and the problem of high probability of wall attachment of a calcium-free roasting process is substantially solved.

Molten liquid phase roasting method of chromite

The invention provides a process for preparing sodium dichromate, namely producing the sodium dichromate through a carbonization method comprising: converting sodium chromate into the sodium dichromate via carbon dioxide under pressurizing condition; delivering sodium chromate neutral liquor with impurities removed to a carbonization tower after a cascade reaction of more than three continuous towers; obtaining carbonizing liquor by controlling different gradient parameters (concentration and temperature of the carbonizing liquor, partial pressure of the carbon dioxide, carbonizing time and the like), continuously carbonizing and separating under pressure; obtaining sodium dichromate finished products through concentrating, filtering, evaporating, crystallizing and centrifugal dehydrating.

Process for preparing sodium dichromate

The invention relates to a comprehensive treatment method for organic wastewater containing inorganic salt and waste residue containing chromium. The method comprises the following steps: (a) providing the organic wastewater containing inorganic salt, adding waste residue containing chromium when the pH of the organic wastewater is 0.1-4.0; (b) carrying out liquid phase reaction on the obtained mixture at 150-400DEG C, then filtering so as to obtain filtrate and filter residue; (c) optionally adding a reducing agent into the obtain filtrate so as to reduce the residual chromium, and then filtering so as to obtain filtrate and filter residue; (d) crystallizing the filtrate obtained in step (b) or (c), so as to obtain inorganic salt crystal and mother liquor; (e) regulating the pH of the mother liquor obtained in the step (d) to be 6.5-7.0, precipitating, and separating so as to obtain a precipitate and a filtrate; (f) optionally returning the filtrate obtained in the step (e) back to production or desalting the filtrate obtained in the step (e) and then discharging. According to the method, organic matters in organic wastewater can be effectively removed, furthermore, inorganic salt in the organic wastewater can be recycled, the processed wastewater can be returned back for industrial application or simply desalted so as to be discharged directly, and chromium in the waste residue containing chromium can be recycled.

Comprehensive treatment method for organic wastewater containing inorganic salt and waste residue containing chromium

The invention relates to a method for treating naphthoquinone production liquid waste containing hexavalent chromium and vitamin K3 production wastewater and co-producing chromium oxide green. The method comprises the following steps: a) carrying out liquid phase reaction between the naphthoquinone production liquid waste and the vitamin K3 production wastewater at 80-260 DEG C, wherein the naphthoquinone production liquid waste is excessively used relative to a necessary dosage of complete reduction; b) adding a reducing agent into the obtained reaction mixture to reduce the residual hexavalent chromium; c) regulating the pH of the obtained reaction mixture to 5.5-8.5 to separate out chromium hydroxide, and separating to obtain the chromium hydroxide and filtrate; and d) transforming the chromium hydroxide obtained in the step c) into chromium oxide green. The method can be used for effectively treating the naphthoquinone production liquid waste and the vitamin K3 production wastewater generated in a vitamin K3 production chain and recycling effective components in the liquid waste to turn waste into wealth and improve the economic and environmental protection benefits at the same time.

Method for treating naphthoquinone production liquid waste containing hexavalent chromium and vitamin K3 production wastewater and co-producing chromium oxide green

Li Xianrong

Papers

Molten liquid phase roasting method of chromite

Process for preparing sodium dichromate

Comprehensive treatment method for organic wastewater containing inorganic salt and waste residue containing chromium

Method for treating naphthoquinone production liquid waste containing hexavalent chromium and vitamin K3 production wastewater and co-producing chromium oxide green

Preparation method of sodium bichromate