CN1240763A - Process for preparing sodium chlomate and sodium bichromate by pure-oxygen alkali fusion method - Google Patents

Process for preparing sodium chlomate and sodium bichromate by pure-oxygen alkali fusion method Download PDF

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Publication number
CN1240763A
CN1240763A CN 98110325 CN98110325A CN1240763A CN 1240763 A CN1240763 A CN 1240763A CN 98110325 CN98110325 CN 98110325 CN 98110325 A CN98110325 A CN 98110325A CN 1240763 A CN1240763 A CN 1240763A
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China
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high temperature
oxygen
sodium
fusion
caustic soda
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CN 98110325
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张志礼
马贵宦
韩惠田
孙忠寿
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MINGGUANG CHEMICAL PLANT LONGKOU CITY
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MINGGUANG CHEMICAL PLANT LONGKOU CITY
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Abstract

A process for preparing sodium chromate with chromium ore and sodium hydroxide as raw materials includes mixing raw materials, high-temp fusing while blowing in pure oxygen, diluting, separation, evaporation, cooling while crystallizing, centrifugal drying, recovering mother liquid and iron dregs washing. A process for preparing sodium bichromate is based on above-mentioned process and includes such additional steps as dissolving, neutralization, separation, acidifying, evaporation, separation, evaporation, cooling crystallization, dewatering and recovering mother liquid. Its advantages are simple process, less investment, high yield of product, high purity and less discharged waste dregs decreased by 3/4.

Description

The pure oxygen alkali fusion is produced the method for Sodium chromate and sodium dichromate 99
The present invention relates to a kind of pure oxygen alkali fusion and produce the method for Sodium chromate and sodium dichromate 99, belong to inorganic salt manufacturing technology field.
Sodium chromate (Na 2Cr 2O 44H 2O) be the basic raw material of producing sodium dichromate 99, chrome yellow etc.Sodium dichromate 99 (Na 2Cr 2O 7), have another name called arsenic, be the basic raw material of chromic salts products such as production potassium bichromate, chromic anhydride, chrome green, the two all belongs to important Inorganic Chemicals.Be widely used in that plating, process hides, printing and dyeing, medicine, grease are refining, industry such as catalyzer, synthetic rubber, spices and stainless steel manufacturing.Along with the development of China and world economy, its demand is more and more.But the production of Sodium chromate, sodium dichromate 99 mainly exists environmental pollution serious at present, and production efficiency is low, the deficiency of yield low (only being 75%), and environmental pollution is particularly outstanding.In China, 1 ton of sodium dichromate 99 of every production needs 3 tons of chromium slags of discharging, produces 100000 tons of sodium dichromate 99s per year as if pressing, and then the whole nation is annual discharges 300,000 tons of chromium slags, and the difficulty of governance of chromium slag is very big.From the sixties so far, China and countries in the world one are until the research of power in treatment of chromate slag.Up to last year, just had than quantum jump, invented a kind of method that adopts chrome ore, alkali, solid oxidizing agent to produce Sodium chromate, sodium dichromate 99, removed mass filler, the discharging of chromium slag significantly reduces, and manufacturing process is simple, and facility investment reduces.But the quality of producing product is subject to the influence of oxygenant, carbonic acid gas etc., has increased treatment process and cost.
The purpose of this invention is to provide that a kind of manufacturing process is simpler, production efficiency is high, the discharging of chromium slag further reduces, and environmental pollution is little, and the pure oxygen alkali fusion that the quality of production is high is produced the method for Sodium chromate and sodium dichromate 99.
The objective of the invention is to reach by the following technical programs.
A kind of technical solution of the present invention is to produce Sodium chromate with the pure oxygen alkali fusion.Its special character is, it comprises mixes 1, high-temperature fusion 2, and dilution 3 separates 4, evaporation 5, crystallisation by cooling 6, water dumping 7, mother liquor reclaims 8, and scum washs 9 all operations.In mixing 1 two kinds of raw materials are only arranged, a kind of is chrome ore, and another kind is a caustic soda, and the weight ratio of chrome ore and caustic soda is chrome ore: caustic soda=1: 1.7～5.In high-temperature fusion 2, in the retort that holds high temperature melt substance, be blown into the oxygenant of purity oxygen as reaction, the amount that is blown into purity oxygen is enough to make high temperature melt substance that oxidizing reaction takes place fully.
In high-temperature fusion 2, the oxygen that is blown into and the weight ratio of high temperature melt substance are high temperature melt substance: purity oxygen=2.7～6: 0.32～4.8.
Second kind of technical solution of the present invention is to produce the method for sodium dichromate 99 with the pure oxygen alkali fusion.To wash 9 all operations to scum identical with first kind of technical solution from mixing 1, all belongs to the operation for preparing Sodium chromate.From dissolve 10 to considering wash heat to wash 21 are the operations that prepared sodium dichromate 99 by Sodium chromate.Specifically, this method comprises following tens kinds of operations, promptly mixes 1, high-temperature fusion 2, dilution 3 separates 4, evaporation 5, crystallisation by cooling 6, water dumping 7, mother liquor reclaims 8, scum washing 9, dissolving 10, in and 11, separate 12, acidifying 13, evaporation 14 separates 15, evaporation 16, crystallisation by cooling 17, dehydration 18, mother liquor reclaims 19, and saltcake washing 20 is considered wash heat and is washed 21.Mixing in 1, it is chrome ore that used raw material has only the weight ratio of chrome ore and caustic soda chrome ore and caustic soda: caustic soda=1: 1.7～5.In high-temperature fusion 2, in the retort that holds high temperature melt substance, be blown into the oxygenant of purity oxygen as reactant, the amount that is blown into purity oxygen is enough to make high temperature melt substance that oxidizing reaction takes place fully.
In high-temperature fusion 2, the oxygen that is blown into and the weight ratio of high temperature melt substance are high temperature melt substance: purity oxygen=2.7～6: 0.32～4.8.
The mechanism of producing Sodium chromate and sodium dichromate 99 is: the major ingredient of chrome ore is Cr 2O 3, at high temperature (500～600 ℃), chrome ore and caustic soda are in molten state, the Cr in the chrome ore 2O 3With caustic soda (N aOH), under the strong oxidation of the purity oxygen that is blown into, react, 1～2 hour time, behind the generation Sodium chromate, high temperature melt substance to be poured in the encloses container of rotation, high temperature melt substance is in flow state, mixes with water.The venting port of the heat steam that produces in encloses container discharged dilution time 1～1.5 hour.Compounding substances after the dilution, through conventional device separates, filtrate is after evaporation, and crystallisation by cooling after water dumping, makes Sodium chromate (Na again 2Cr 2O 44H 2O) separate with mother liquor, produce finished product, mother liquor is after evaporation, and the residual caustic soda in it is recycled, and scum is after water cleans, and filtrate is returned the dilution operation and utilized tapping again.Finished the manufacturing processed of Sodium chromate thus.And then produce sodium dichromate 99 by Sodium chromate.Earlier the solid Sodium chromate is put in the reaction vessel, water filling dissolving then adds the acid neutralization, removes small amount of alkali, forms aluminum hydroxide precipitation simultaneously, is removed through separation, and the filtrate behind precipitation separation makes Sodium chromate be transformed into sodium dichromate 99 through acidifying, and saltcake (N is arranged simultaneously A2SO 4) generate, after evaporation, to separate out, and separate and remove, the solution behind the separation saltcake has sodium dichromate crystal to separate out after evaporation, cooling, and sodium dichromate 99 becomes product through dehydration, the recyclable utilization of dehydration mother liquor.
Chrome ore and caustic soda are only arranged owing to the present technique solution is raw materials used, make oxygenant with purity oxygen, chrome ore under high temperature fused state absorbs the oxygen that is blown into rapidly strong oxidizing reaction has taken place, both overcome purity oxygen and can not directly feed the interior prejudice of high-temperature fusion chrome ore container, improved oxidation rate again, by original oxidization time 2～3 hours, bring up to 1-2 hour; Also eliminated because of Carbon Dioxide in Air enters the high-temperature fusion chrome ore and generated carbonate (N A2CO 3) cause material melting temperature to increase, the problem of mobile variation has been saved the technology of later process carbonate, has improved the quality of product; Avoided the adding because of solid oxidizing agent (as nitrate such as SODIUMNITRATE, the sour potassium of pin) again, caused the low deficiency of quality product, quality product has improved 3 percentage points.But also reduced cost.Owing to have only chrome ore and caustic soda in the raw material, do not have other auxiliary material, so produce the chromium quantity of slag that 1 ton of sodium dichromate 99 is discharged, only be 27.3% of old technology, producing 1 ton of amount that Sodium chromate discharges the chromium slag, only is 17.45% of old technology, has fundamentally solved the amount that produces waste residue.
The explanation of accompanying drawing drawing
Fig. 1-the present invention produces a process flow sheet of Sodium chromate
Fig. 2-the present invention produces a process flow sheet of sodium dichromate 99
Provide embodiments of the invention below in conjunction with accompanying drawing, be used for further specifying technical solution.
Owing to produce the technology of sodium dichromate 99, all comprised the technology of producing Sodium chromate, therefore, provide the embodiment that produces sodium dichromate 99 here, the technology of producing Sodium chromate just has been described simultaneously.
Embodiment 1, with reference to figure 1, Fig. 2.Mixing in 1, in chrome ore: the ratio of caustic soda=1: 3, drop into 100 kilograms of raw materials in the retort of rotating, the reacting by heating jar makes that material temperature reaches 500～600 ℃ in the retort, thereby entered high-temperature fusion 2, in jar, be blown into pure oxygen 120kg here, (be equivalent to high temperature melt substance: oxygen=3: 0.36), 1 hour time length, make high temperature melt substance that a series of physicochemical change take place, the trivalent chromium in the chrome ore is oxidized to sexavalent chrome.To be oxidized to chromic mixture then and pour in the encloses container of band stirring, enter dilution operation 3.Here, in high temperature melt substance: the ratio of water=1: 4 is input to water in encloses container that another band stirs, turn switch, high temperature melt substance is slowly flowed in the encloses container that is filled with water, make high temperature melt substance dilution cooling, at this moment, the Na in the mixture +, GO 4 2-, OH -Etc. soluble in water, other insoluble substance exists with solid state, enters separation circuit 4 then.In this operation, will separate by the liquid mixture that the dilution operation obtains with pressure filter, solution enters a container, and filter residue (being scum) enters another container.With the solution heating evaporation in the container, thereby enter evaporization process 5, here the water evaporates in the solution has been fallen, mixture has been sent in the water cooler cooled off then, thereby entered refrigerating work procedure 6.In this operation, make Sodium chromate (N A2Cr 2O 44H 2O) from concentrated base, crystallize out, enter water dumping operation 7 then.With water extracter crystals of sodium chromate is separated with mother liquor (liquid caustic soda) here, thereby produce the solid Sodium chromate.Through dewater isolated mother liquor in mother liquor recovery process 8 in advance to reclaim, in this operation, with mother liquid evaporation, the remaining caustic soda in evaporation back is recycled.Enter filter residue (scum) in another container in scum washing procedure 9, with flushing with clean water 2-3 time, the material of contained solubility wherein, soluble in water, import in the container and store, so that in dilution operation 3, be used for diluting the chrome ore of high-temperature fusion, utilize again after the scum after the cleaning is stored and just can.Finished the production process of Sodium chromate thus.And then the following operation of process is produced sodium dichromate 99.
With the solid Sodium chromate that obtains in dissolution process 10 with its dissolving, in solution, add then sulfuric acid enter in and operation 11, adding the vitriolic purpose, is to make the impurity in the solution form precipitation, after the heated and boiled, make more impurity form precipitation, enter separation circuit 12 then, in this operation, material is separated with pressure filter, solution enters a container and carries out acidifying, and filter residue enters another container.In acidizing process 13, in container, add an amount of sulfuric acid, make the Sodium chromate dehydration change into sodium dichromate 99, change evaporization process 14 then over to.Filter residue adds water washing (residue washing operation 21) in another container, the recovery of soluble chromium alkali and filtrate are used to dissolve Sodium chromate.In evaporization process 14, evaporate the moisture content in the solution, at first make saltcake (N A2SO 4) crystallization separates out, and enters separation circuit 15 then.In separation circuit 15, the solid saltcake is separated with solution, the saltcake after the separation is recycled soluble sodium salt through saltcake washing procedure 20.Solution after the filtration, enter in the evaporization process 16, here, make the moisture content in the solution further obtain evaporation, enter crystallisation by cooling operation 17 then, here, sodium dichromate crystal is separated out, put it into dehydration in the water trap then, entered dehydration procedure 18 thus, here, with water extracter the solid sodium dichromate 99 is separated with mother liquor, produced sodium dichromate 99 thus, isolated mother liquor flows in mother liquor recovery process 18 in the container in advance reclaiming, in then it being guided to and operation be used.Characteristics, prepared using is abundant, and technology is simple, and filter residue is few, production efficiency and product yield height.
Embodiment 2, with reference to figure 1, Fig. 2.Mixing in 1, chrome ore: caustic soda=1: 1.7, raw material weight still are 100 kilograms, in high-temperature fusion 2, the purity oxygen that is blown into be 36Kg (be equivalent to high temperature melt substance: oxygen=4: 1.44), in dilution operation 3, high temperature melt substance: water=1: 10.The course of processing of other parts is identical with embodiment 1.Compare with embodiment 1, because of caustic soda reduces, the raw material heating, when becoming high temperature melt substance, its mobile variation, but because of used amount of oxygen has increased by three times, therefore, oxidation rate is accelerated.Because of caustic soda amount reduces, its production cost slightly descends.
Embodiment 3, with reference to figure 1, Fig. 2.Mixing in 1, chrome ore: caustic soda=1: 5, raw material weight still are 100 kilograms, and in high-temperature fusion 2, the purity oxygen that is blown into is 48 kilograms and (is equivalent to high temperature melt substance: oxygen=6: 1.92).The course of processing of other parts is identical with embodiment 1.Compare with embodiment 1, because of the caustic soda consumption increases, the flowability of high temperature melt substance is good, and used amount of oxygen increases, and oxidation rate is accelerated, and the yield of sodium dichromate 99 improves, but production cost improves.
Embodiment 4, with reference to figure 1, Fig. 2, mixing in 1, chrome ore: caustic soda=1: 4, raw material weight still are 100 kilograms, in high-temperature fusion 2, the purity oxygen that is blown into is that 80kg (is equivalent to high temperature and dissolves material: oxygen=6: 4.8).The course of processing of other parts is identical with embodiment 1.Compare with implementing 1, the caustic soda consumption has increase, high temperature melt substance mobile better.Used oxygen increases, and oxidation rate is further accelerated, and the yield of production efficiency and sodium dichromate 99 is improved.But cost up.
In like manner,, can also provide a plurality of embodiment, all belong to protection scope of the present invention according to claim protection domain that limits and the technical solution that this specification sheets provides.

Claims (4)

1, a kind of pure oxygen alkali fusion is produced the method for Sodium chromate, it is characterized in that it comprises: mix (1), high-temperature fusion (2), dilution (3) separates (4), evaporation (5), crystallisation by cooling (6), water dumping (7), mother liquor reclaims (8), scum washing (9) all operations, in mixing (1), used raw material is chrome ore and caustic soda, and the weight ratio of chrome ore and caustic soda is: chrome ore: caustic soda=1: 1.7～5.In high-temperature fusion (2), in the retort that holds high temperature melt substance, be blown into the oxygenant of purity oxygen as reactant, the amount that is blown into purity oxygen is enough to make high temperature melt substance that oxidizing reaction takes place fully.
2, produce the method for Sodium chromate according to the described pure oxygen alkali fusion of claim 1, it is characterized in that, in high-temperature fusion (2), the oxygen that is blown into and the weight ratio of high temperature melt substance are: high temperature melt substance: purity oxygen=2.7～6: 0.32～4.8.
3, a kind of pure oxygen alkali fusion is produced the method for sodium dichromate 99, it is characterized in that it comprises mixing (1), high-temperature fusion (2), dilution (3) separates (4), evaporation (5), crystallisation by cooling (6), water dumping (7), mother liquor reclaims (8), scum washing (9), dissolving (10), neutralization (11), separate (12) acidifying (13), evaporation (14), separate (15), evaporation (16), crystallisation by cooling (17), dehydration (18), mother liquor reclaims (19), saltcake washing (20) is considered wash heat and is washed (21) all operations, in mixing (1), used raw material is chrome ore and caustic soda, the weight ratio of chrome ore and caustic soda is chrome ore: caustic soda=1: 1.7～5, in high-temperature fusion (2), be blown into the oxygenant of purity oxygen as reactant in the retort that holds high temperature melt substance, the amount that is blown into purity oxygen is enough to make high temperature melt substance that oxidizing reaction takes place fully.
4, pure oxygen alkali fusion according to claim 3 is produced the method for sodium dichromate 99, it is characterized in that, in high-temperature fusion (2), the oxygen that is blown into and the weight ratio of high temperature melt substance are high temperature melt substance: purity oxygen=2.7～6: 0.32～4.8.
CN 98110325 1998-06-29 1998-06-29 Process for preparing sodium chlomate and sodium bichromate by pure-oxygen alkali fusion method Pending CN1240763A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004083123A1 (en) * 2003-03-19 2004-09-30 Institute Of Process Engineering Chinese Academy Of Sciences Method for production of alkali metal chromates
CN101892490A (en) * 2010-06-24 2010-11-24 中国科学院青海盐湖研究所 Method for continuously preparing sodium dichromate by ionic membrane electrolysis

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004083123A1 (en) * 2003-03-19 2004-09-30 Institute Of Process Engineering Chinese Academy Of Sciences Method for production of alkali metal chromates
US7968066B2 (en) 2003-03-19 2011-06-28 Institute Of Process Engineering Chinese Academy Of Sciences Method for production of alkali metal chromates
CN101892490A (en) * 2010-06-24 2010-11-24 中国科学院青海盐湖研究所 Method for continuously preparing sodium dichromate by ionic membrane electrolysis

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