CN102976991A - Method for extracting thiocarbamide from desulfurization rich liquor - Google Patents
Method for extracting thiocarbamide from desulfurization rich liquor Download PDFInfo
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- CN102976991A CN102976991A CN2012105163468A CN201210516346A CN102976991A CN 102976991 A CN102976991 A CN 102976991A CN 2012105163468 A CN2012105163468 A CN 2012105163468A CN 201210516346 A CN201210516346 A CN 201210516346A CN 102976991 A CN102976991 A CN 102976991A
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Abstract
The invention discloses a method for extracting thiocarbamide from desulfurization rich liquor, which comprises the following steps: adding activated carbon, accounting for 0.2-0.45 wt% of desulfurization rich liquor, into the desulfurization rich liquor to carry out decolorization; after removing ammonium thiosulfate, adding barium sulfide, treating the generated gas with lime cream to obtain a calcium hydrosulfide solution, and treating the reaction solution with lime cream to obtain a calcium cyanamide solution; mixing the calcium hydrosulfide solution and calcium cyanamide solution in a certain proportion to react to obtain a thiocarbamide liquid; evaporating, filtering, cooling and crystallizing to obtain crystal thiocarbamide; and carrying out centrifugal dewatering and drying to obtain the finished product. The method for preparing thiocarbamide directly from desulfurization rich liquor has the characteristics of high efficiency and high product purity, and is ecological and environment-friendly.
Description
Technical field
The invention belongs to the recycling field of coal chemical industrial waste water, be specifically related to a kind of method of from sulfur removing pregnant solution, extracting thiocarbamide.
Background technology
Adopt in HPF method, FR method, ADA method and the AS method wet desulfurizing process take ammonia or yellow soda ash as alkali source at coal chemical enterprise at present, doctor solution is after saltiness reaches certain value, desulfuration efficiency can reduce, must replenish new doctor solution behind a part of doctor solution of discharging, this part doctor solution of discharge becomes sulfur removing pregnant solution again.China's coke output to 2006 year reaches 30,000 ten thousand tons, accounts for 57% of global total amount, becomes production the biggest in the world, consumption and export State.Produce the coal chemical enterprise of 1,000,000 tons of cokes per year, the sulfur removing pregnant solution amount of generation is about 30 tons/day.According to conservative estimation, the sulfur removing pregnant solution amount that national coke manufacturing enterprise produces every day is approximately more than 10,000 ton (dry desulfurization does not produce waste liquid, but the producer of domestic employing dry desulfurization seldom), annual more than 300 ten thousand tons of the sulfur removing pregnant solutions that produce.
According to the Site Detection analysis, the main component of sulfur removing pregnant solution is divided into two large classes: the sulfur removing pregnant solution take ammonia as alkali source mainly contains ammonium thiocyanate, ammonium thiosulfate and ammonium sulfate etc.; And the sulfur removing pregnant solution take yellow soda ash as alkali source mainly contains Sodium Thiocyanate 99, Sulfothiorine and sodium sulfate etc.At present a lot of research institutions or coal chemical enterprise have all been carried out research or the practice of extraction thiocyanate-, and extraction cost is higher, product purity is lower but all exist, the deficiencies such as produce market sales difficulty.How to utilize sulfur removing pregnant solution to become the important topic that not only concerns environmental protection but also affect the coal chemical enterprise low carbon development, have very important Ecological Society meaning and economic implications.
Thiocarbamide (being commonly called as thio urea) is widely used in makes sulfonamide, dyestuff, resin, molding powder etc., also as the vulcanization accelerator of rubber, the flotation agent of metalliferous mineral etc., thiocarbamide is again a kind of important chemical intermediate simultaneously, and itself and hydrogen peroxide oxidation can obtain thiourea peroxide.Thiourea peroxide is a kind of novel strong reductant, is the preferred materials of sewage disposal de-sludging, and it all is widely used at aspects such as printing and dyeing industry, paper industry, high polymer synthesis industries.At present the method for preparing thiocarbamide commonly used is to absorb under negative pressure, cooling with milk of lime that to vulcanize be the preferred materials of sewage disposal de-sludging, and it all is widely used at aspects such as printing and dyeing industry, paper industry, high polymer synthesis industries.The method for preparing thiocarbamide commonly used is with milk of lime absorbing hydrogen sulphide under negative pressure, cooling at present, generate calcium sulfhydrate solution, calcium sulfhydrate and calcium cyanamide (lime nitrogen) pressed 1: 5 mol ratio thereafter, in about 80 ℃, react 3h, namely get thiourea solution, filter, concentrated, crystallisation by cooling, rejection filter be dry, gets the finished product thiocarbamide.This method prepares the thiocarbamide long flow path, and production efficiency is low, causes product cost higher.
Directly prepare thiocarbamide with sulfur removing pregnant solution and have efficient height, good product purity, the characteristics of ecological, environmental protective.
Summary of the invention
The object of the present invention is to provide a kind of take sulfur removing pregnant solution as raw material, improve and to prepare the method that thiocarbamide efficient, good product purity and ecological, environmental protective directly extract the thiocarbamide product.
For achieving the above object, the technical solution used in the present invention is: add 20～45 kilograms of gacs in 1000 kilograms of sulfur removing pregnant solutions, and add a certain amount of iodine (I
2) as oxygenant, the add-on of oxygenant is advisable for the desulfurization catalyst in the energy oxidation sweetening rich solution; Waste liquid is heated to 70～100 ℃, keeps stirring 1～2 hour, filter; Minute three demi continuities add mass concentration less than 25% sulfuric acid in the filtrate in closed unit, make the final PH=3.0 of waste liquid～5.5, be heated to 60～90 ℃, keep stirring 1～3 hour, the sulfur dioxide gas body and function conduit of effusion is drawn and is absorbed with discarded milk of lime; Reacting liquid filtering, detect ammonium sulfate amount of substance in the filtrate, add with filtrate in the barium sulphide of the amount such as ammonium sulfate, in sealed vessel, be heated to 60～80 ℃, keep stirring 1～2 hour, ammonia and the hydrogen sulfide of overflowing make calcium sulfhydrate solution through the milk of lime negative pressure absorbing, draw and the water absorption with conduit.Above-mentioned reaction is filtered after finishing, and adds milk of lime in the filtrate to make calcium cyanamide solution.The mol ratio of calcium sulfhydrate and calcium cyanamide is 1: (4～6), under constantly stirring, temperature of reaction is 70～90 ℃, reaction times is 1～3h, through negative pressure filtration, can generate thiocarbamide liquid, again through evaporation, filtration, cooling, crystallization, namely get the crystal thiocarbamide, centrifugal drying gets product.
A kind of method of from sulfur removing pregnant solution, extracting thiocarbamide that adopts that technique scheme provides compared with prior art, technique effect is:
The purity of the thiocarbamide product that 1. extracts is more than 95%, for industry provides raw material;
2. the main raw material of technique derives from waste water utilization, and good social benefit and economic benefit are arranged.
Embodiment
Below in conjunction with embodiment the specific embodiment of the present invention is described in further detail.
Described a kind of method of extracting thiocarbamide from sulfur removing pregnant solution is to add 20～45 kilograms of gacs in 1000 kilograms of sulfur removing pregnant solutions, adds oxygenant, and the add-on of oxygenant is advisable for the desulfurization catalyst in the energy oxidation sweetening rich solution; Waste liquid is heated to 70～100 ℃, keeps stirring 1～2 hour, filter.Minute three demi continuities add mass concentration less than 25% sulfuric acid in the filtrate in closed unit, make the final PH=3.0 of waste liquid～5.5, be heated to 60～90 ℃, keep stirring 1～3 hour, the sulfur dioxide gas body and function conduit of effusion is drawn and is absorbed with discarded milk of lime; Reacting liquid filtering, detect ammonium sulfate amount of substance in the filtrate, add with filtrate in the barium sulphide of the amount such as ammonium sulfate, in sealed vessel, be heated to 60～80 ℃, keep stirring 1～2 hour, ammonia and the hydrogen sulfide of overflowing make calcium sulfhydrate solution through the milk of lime negative pressure absorbing, draw and the water absorption with conduit; Above-mentioned reaction is filtered after finishing, add milk of lime in the filtrate and make calcium cyanamide solution, the mol ratio of calcium sulfhydrate and calcium cyanamide is 1: (4～6), and under constantly stirring, temperature of reaction is 70～90 ℃, reaction times is 1～3h, through negative pressure filtration, can generate thiocarbamide liquid, again through evaporation, filtration, cooling, crystallization, get the crystal thiocarbamide, get finished product after the centrifugal drying; Wherein oxygenant is selected iodine, and sulfur removing pregnant solution refers to take ammonia or calcium carbonate as alkali source, and the value of the saltiness in wet desulfurizing process in doctor solution reduces desulfuration efficiency and the part doctor solution that must discharge.
Embodiment 1
Get 1000 kilograms of coke-oven plant, Hunan sulfur removing pregnant solutions, in 1000 kilograms of sulfur removing pregnant solutions, add 25 kilograms of gacs, and add a certain amount of iodine (I
2) as oxygenant, the add-on of oxygenant is advisable for the desulfurization catalyst in the energy oxidation sweetening rich solution; Waste liquid is heated to 80 ℃, keep stirring 2 hours, filter, minute three demi continuities add mass concentration less than 25% sulfuric acid in the filtrate in closed unit, make the final PH=3.5 of waste liquid, 80 ℃ of constant temperature keep stirring 3 hours, and the sulfur dioxide gas body and function conduit of effusion is drawn and absorbed with discarded milk of lime.Reacting liquid filtering, detect ammonium sulfate amount of substance in the filtrate, add with filtrate in the barium sulphide of the amount such as ammonium sulfate, in sealed vessel, be heated to 80 ℃, keep stirring 2 hours, ammonia and the hydrogen sulfide of overflowing make calcium sulfhydrate solution through the milk of lime negative pressure absorbing, draw and the water absorption with conduit.Above-mentioned reaction is filtered after finishing, and adds milk of lime in the filtrate to make calcium cyanamide solution.The mol ratio of calcium sulfhydrate and calcium cyanamide is 1: 4.5, and under constantly stirring, temperature of reaction is 80 ℃, reaction times is 3h, through negative pressure filtration, generates thiocarbamide liquid, through evaporation, filtration, cooling, crystallization, get the crystal thiocarbamide again, centrifugal drying gets product.
Embodiment 2
Get 1000 kilograms of coke-oven plant, Ezhou, Hubei sulfur removing pregnant solutions, in 1000 kilograms of sulfur removing pregnant solutions, add 45 kilograms of gacs, and add a certain amount of iodine (I
2) as oxygenant, the add-on of oxygenant is energy oxygen PH=4.0, is heated to 90 ℃, keeps stirring 2 hours, the sulfur dioxide gas body and function conduit of effusion is drawn and is absorbed with discarded milk of lime; Reacting liquid filtering, detect ammonium sulfate amount of substance in the filtrate, add with filtrate in the barium sulphide of the amount such as ammonium sulfate, in sealed vessel, be heated to 70 ℃, keep stirring 2 hours, ammonia and the hydrogen sulfide of overflowing make calcium sulfhydrate solution through the milk of lime negative pressure absorbing, draw and water absorbs with conduit. and filter after above-mentioned reaction finishes, add milk of lime in the filtrate to make calcium cyanamide solution.The mol ratio of calcium sulfhydrate and calcium cyanamide is 1: 6, and under constantly stirring, temperature of reaction is 70 ℃, and the reaction times is 2h, through negative pressure filtration, generates thiocarbamide liquid, again through evaporation, filtration, cooling, crystallization, gets the crystal thiocarbamide, and centrifugal drying gets product.
Claims (1)
1. method of extracting thiocarbamide from sulfur removing pregnant solution is characterized in that: add 20～45 kilograms of gacs in 1000 kilograms of sulfur removing pregnant solutions, add oxygenant, the add-on of oxygenant is advisable for the desulfurization catalyst in can the oxidation sweetening rich solution; Waste liquid is heated to 70～100 ℃, keeps stirring 1～2 hour, filter; Minute three demi continuities add mass concentration less than 25% sulfuric acid in the filtrate in closed unit, make the final PH=3.0 of waste liquid～5.5, be heated to 60～90 ℃, keep stirring 1～3 hour, the sulfur dioxide gas body and function conduit of effusion is drawn and is absorbed with discarded milk of lime; Reacting liquid filtering, detect ammonium sulfate amount of substance in the filtrate, add with filtrate in the barium sulphide of the amount such as ammonium sulfate, in sealed vessel, be heated to 60～80 ℃, keep stirring 1～2 hour, ammonia and the hydrogen sulfide of overflowing make calcium sulfhydrate solution through the milk of lime negative pressure absorbing, draw and the water absorption with conduit; Above-mentioned reaction is filtered after finishing, add milk of lime in the filtrate and make calcium cyanamide solution, the mol ratio of calcium sulfhydrate and calcium cyanamide is 1: (4～6), and under constantly stirring, temperature of reaction is 70～90 ℃, reaction times is 1～3h, through negative pressure filtration, can generate thiocarbamide liquid, again through evaporation, filtration, cooling, crystallization, get the crystal thiocarbamide, get finished product after the centrifugal drying; Wherein
Oxygenant is selected iodine;
Sulfur removing pregnant solution refers to that take ammonia or yellow soda ash as alkali source the value of the saltiness in doctor solution makes desulfuration efficiency reduce the part doctor solution that must discharge in wet desulfurizing process.
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| SU745897A1 (en) * | 1977-01-03 | 1980-07-07 | Предприятие П/Я А-3481 | Method of preparing thiourea |
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| EP0018635A2 (en) * | 1979-05-03 | 1980-11-12 | FMC Corporation | Control of thiosulfate in wet desulfurization process solutions |
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Application publication date: 20130320 |