CN113044857B - Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield - Google Patents
Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield Download PDFInfo
- Publication number
- CN113044857B CN113044857B CN202011608277.4A CN202011608277A CN113044857B CN 113044857 B CN113044857 B CN 113044857B CN 202011608277 A CN202011608277 A CN 202011608277A CN 113044857 B CN113044857 B CN 113044857B
- Authority
- CN
- China
- Prior art keywords
- cyanide
- hcn
- liquid
- reaction
- absorber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C3/00—Cyanogen; Compounds thereof
- C01C3/08—Simple or complex cyanides of metals
- C01C3/10—Simple alkali metal cyanides
Landscapes
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a production process for preparing high-purity sodium cyanide or potassium cyanide with high yield, which comprises the following steps: 1) Removing ammonia and cooling to obtain HCN ammonia; 2) Ammonia removal and split flow of HCN; 3) Carrying out absorption reaction to obtain a crude cyanide solution; 4) Decarburization reaction is carried out to obtain decarburization liquid; 5) Regulating the content of free alkali; the decarbonizing liquid obtained in the step 4) and HCN in the step 2) enter an absorber II to remove ammonia, and absorption reaction is carried out in the absorber II to obtain high-purity liquid sodium cyanide or potassium cyanide; 6) Tail gas treatment; the invention discloses a production device for preparing high-purity sodium cyanide or potassium cyanide with high yield.
Description
Technical Field
The invention belongs to the technical field of cyanide production, and particularly relates to a method and a device for producing high-purity sodium cyanide or potassium cyanide by hydrocyanic acid synthetic gas prepared by an Ann method or a methanol ammoxidation method without purification treatment.
Background
Sodium cyanide and potassium cyanide are used as important chemical products, have multiple purposes, can be widely used for electroplating, metal surface treatment, precious metal extraction and recovery, pesticide manufacturing, organic synthesis, heat treatment process and the like, and are of two types of liquid and solid.
At present, the technological routes for producing sodium cyanide or potassium cyanide at home and abroad are approximately the same, hydrocyanic acid (HCN) and aqueous solution of sodium hydroxide or potassium hydroxide are adopted to react to produce liquid sodium cyanide or potassium cyanide, and then the solid sodium cyanide or potassium cyanide product is obtained through the procedures of evaporation, crystallization, solid-liquid separation, drying and forming and the like. The use of liquid or solid sodium cyanide or potassium cyanide as a product for downstream applications generally requires a relatively high purity, although small amounts of sodium or potassium hydroxide (free base) must be retained as a stabilizer in the liquid sodium cyanide or potassium cyanide, but the carbonate or formate thereof must be as low as possible.
The hydrocyanic acid can be industrially produced by adopting various technical methods known in the technical field, such as Andrussow method (namely Ann method) which is a main stream synthesis route of global hydrocyanic acid is a catalytic reaction which takes natural gas (or methane gas from other sources), ammonia and air as raw materials, and a synthesis product is HCN synthesis gas containing various components such as carbon dioxide, ammonia, nitrogen, water and the like; in recent years, a rapid methanol ammoxidation method is developed in China, wherein methanol, ammonia and air are used as raw materials for catalytic reaction, and a synthesized product is HCN synthesis gas containing multiple components such as carbon dioxide, ammonia, nitrogen, water and the like; the amberg process or the methanol ammoxidation process is a catalytic synthesis reaction carried out at high temperature, and after waste heat is recovered by a waste heat boiler and cooled, the temperature is generally still up to about 200 ℃. Therefore, if HCN synthesis gas prepared by an Ann method or methanol ammoxidation is directly reacted with an aqueous solution of alkali (sodium hydroxide or potassium hydroxide) to prepare liquid sodium cyanide or potassium cyanide, side reactions of carbon dioxide and alkali to generate carbonate impurities exist in the system at the same time; sodium cyanide or potassium cyanide will decompose at higher temperatures to form formate salts, which become another impurity in the system. Carbonates and formates are the primary impurities affecting the quality of sodium cyanide or potassium cyanide products and are therefore required to be as low as possible.
In order to obtain sodium cyanide or potassium cyanide with high purity and low impurity content, pure liquid hydrocyanic acid is required to react with aqueous solution of alkali; for example, U.S. Pat. nos. 2708151 and 2726139 disclose a process for producing sodium cyanide using pure hydrocyanic acid, which can produce liquid sodium cyanide having high purity and low impurity content, and obtain solid sodium cyanide having high purity by the steps of evaporation, crystallization, solid-liquid separation, drying and molding; however, the preparation of purified hydrocyanic acid from hydrocyanic acid synthesis gas prepared by an Anshi method, a methanol ammoxidation method and the like requires expensive equipment such as absorption, rectification, separation and the like, the process flow is complex, and the investment cost and the operation cost are greatly increased; the pure liquid hydrocyanic acid is extremely easy to polymerize, sodium cyanide or potassium cyanide is prepared by the reaction of the pure liquid hydrocyanic acid and alkali, and the requirement on reaction control is high in order to avoid polymerization side reaction.
Attempts have therefore been made to produce sodium cyanide or potassium cyanide by direct mixing and absorption reactions of impure HCN synthesis gas with an alkaline absorption liquid.
US patent 3619132 uses impure HCN synthesis gas to produce sodium cyanide, but the impure HCN synthesis gas is otherwise treated and does not contain carbon dioxide and thus does not produce sodium carbonate impurities.
US2616782 also describes a process wherein calcium hydroxide is added to NaOH in equal or excess to carbon dioxide in HCN synthesis gas, and the carbon dioxide is reacted with the calcium hydroxide to form a calcium carbonate precipitate which is removed; aiming at the synthesis gas obtained by the Anshi method, the HCN synthesis gas containing ammonia, carbon dioxide and the like at the temperature of 300 ℃ is contacted and reacted with a caustic soda solution with the concentration of 47% and suspended with a certain amount of calcium hydroxide by a washing tower, the reaction temperature is controlled to be lower than 150 ℃, and the discharged material flows out from the bottom of the tower and passes through a filtering device to remove the generated calcium carbonate and unreacted lime so as to obtain liquid sodium cyanide with higher purity; the process can well control the residual carbonate content in the liquid sodium cyanide, but the absorption reaction of hydrocyanic acid is carried out under the conditions of higher temperature and ammonia content, so that partial sodium cyanide is inevitably decomposed to generate a certain amount of sodium formate due to overhigh temperature, and the ammonia content in the prepared liquid sodium cyanide also affects downstream application; the direct absorption causes most of water in the synthesis gas (water is generated when the natural gas is subjected to ammoxidation to generate hydrocyanic acid) to enter liquid sodium cyanide, so that the concentration of the liquid sodium cyanide is reduced, and the concentration energy consumption for producing solid sodium cyanide by using the liquid sodium cyanide is greatly increased; the calcium hydroxide suspended in the feed liquid and the generated calcium carbonate precipitate are easy to stay in the tower body to cause tower blockage.
International patent WO2010/135733A describes a production process for producing solid sodium cyanide comprising: (a) using impure hydrocyanic acid gas and sodium hydroxide to be thoroughly mixed in a reactor, but for a maximum period of time of not more than 5s, (b) feeding the mixed product into a continuous evaporation crystallizer for evaporation to obtain a suspension of sodium cyanide, (c) transferring the suspension of sodium cyanide from the crystallizer to a hot planner, precipitating sodium carbonate on the hot planner for removal, and then feeding the suspension back into the crystallizer, (d) then separating the sodium cyanide from the suspension; however, the method produces a large amount of sodium carbonate and produces solid precipitates of sodium carbonate, which are separated from the liquid sodium cyanide by adding precipitates, and the thermal planner for receiving the sodium carbonate deposit needs to be cleaned or cleaned periodically. The method has the advantages of long process flow, complex operation, short residence time of the impure HCN gas in the reactor, and low utilization rate of HCN, and the absorbed tail gas also contains a large amount of HCN.
Chinese patent CN88106890 describes a process for producing solid sodium cyanide by directly absorbing impure HCN synthesis gas containing carbon dioxide in sodium hydroxide solution, i.e. precipitating sodium carbonate produced by the reaction of sodium hydroxide with carbon dioxide, feeding the liquid sodium cyanide formed containing sodium carbonate precipitate directly into a crystallizer, preferably a fractional crystallizer, without removing sodium carbonate, the fine crystals containing sodium carbonate being discharged from the upper part of the crystallizer with mother liquor, the mother liquor being recycled to the absorber, and the larger slurry of sodium cyanide crystals being discharged from the bottom of the crystallizer; the method requires that carbon dioxide in the impure HCN gas is preferably controlled to be 0.5-1.5%, formate is easy to generate when the reaction liquid is at a higher temperature for a long time, a large amount of sodium carbonate is still generated in the absorption process, and high-purity liquid sodium cyanide with low sodium carbonate content can not be directly obtained. Sodium carbonate is discharged along with mother liquor in a crystallizer in a grading way, and then returned to an absorber for cyclic absorption, so that the production process is complex.
Chinese patent CN102502708 proposes a method for preparing alkali metal or alkaline earth metal cyanide with high yield and high purity, which adopts an ampere method to prepare a cyanogen solution by two-stage absorption of HCN synthesis gas mainly containing various components such as HCN, water, ammonia, carbon dioxide, carbon monoxide, hydrogen and nitrogen at 150-300 ℃, wherein the first stage adopts alkali circulation absorption, and the second stage adopts absorption formaldehyde absorption to prepare a hydroxyacetonitrile solution; the reaction time of the first stage absorption is 0.1 to 2.0 seconds, the absorption temperature is 40 to 95 ℃, and the preferable temperature is 60 to 75 ℃; the reaction temperature of the second stage absorption is 0-40 ℃, preferably 10-25 ℃; although the process can prepare the liquid cyanide with relatively high purity without separating carbonate, the content of carbonate and formate in the liquid cyanide can not be further reduced due to the restriction of reaction conditions, the quality difference is still larger compared with that of the liquid cyanide prepared from pure hydrocyanic acid, and the prepared liquid cyanide contains a small amount of ammonia; direct absorption results in a substantial portion of the water in the synthesis gas entering the liquid cyanide, reducing the cyanide concentration, and requiring a higher concentration of base as a feedstock for the production of high cyanide concentrations; the temperature of the HCN synthesis gas entering the first stage absorption is too high, a large amount of absorption circulating liquid is required to cool down in order to ensure that the absorption is carried out at a lower temperature, the energy consumption of a circulating pump is increased, and even so, the side reaction that cyanide in the absorption liquid is heated to generate formate is difficult to effectively control; because the time of the first stage absorption is short, the hydrocyanic acid in the synthesis gas is incompletely absorbed, formaldehyde absorption is adopted as the second stage absorption, a small amount of hydroxy acetonitrile is forced to be co-produced, the product planning is not facilitated, the absorption reaction of the hydroxy acetonitrile needs to be carried out at a lower temperature, a matched refrigerating system is needed, and the investment is increased; because of the inconsistent products of the two-stage absorption, strict gas-liquid separation is required after the first stage absorption in order to avoid bringing cyanide and alkali into the subsequent process.
Disclosure of Invention
In view of the above, the present invention aims to provide a process and a device for producing high purity sodium cyanide or potassium cyanide with high yield, wherein the process and the device for producing high purity sodium cyanide or potassium cyanide with high yield utilize HCN synthesis gas to be divided into two parts after passing through an ammonia removal system, and then enter an absorber I and an absorber II respectively, and part of HCN synthesis gas entering the absorber I is absorbed by sodium hydroxide or potassium hydroxide solution to obtain crude cyanide solution, and then is subjected to decarburization reaction and solid-liquid separation to obtain decarburization solution, and then enters the absorber II to be subjected to absorption reaction with another part of HCN synthesis gas to obtain high purity liquid sodium cyanide or potassium cyanide, so that the purpose of producing high purity sodium cyanide or potassium cyanide with low carbonate and formate content without purification treatment and high yield is achieved, the production cost of the product is low, and the yield is high, and side reactions of the cyanide due to high-temperature decomposition to formate are effectively inhibited.
In order to achieve the above purpose, the invention provides a production process for preparing high purity sodium cyanide or potassium cyanide with high yield, which comprises the following steps:
1) Removing ammonia and cooling: the ammonia in the HCN synthesis gas is removed from the HCN synthesis gas prepared by an Ann method or a methanol ammoxidation method in an ammonia removal system through sulfuric acid or phosphoric acid absorption, and the HCN synthesis gas is cooled to obtain HCN ammonia removal gas;
2) HCN ammonia removal split stream: the HCN ammonia removal obtained in the step 1) is divided into 2 parts, and the 2 parts enter an absorber I and an absorber II respectively, the HCN ammonia removal in the absorber I accounts for 10% -98% of the total volume flow of the HCN ammonia removal, and the rest parts enter the absorber II;
3) Absorption reaction: the HCN ammonia gas entering the absorber I is removed, and the HCN ammonia gas and sodium hydroxide or potassium hydroxide solution are subjected to absorption reaction to obtain a crude cyanide solution;
4) Decarburization reaction: adding calcium oxide, calcium hydroxide, barium oxide or barium hydroxide or a mixture thereof into the crude cyanide solution extracted from the absorber I to perform decarburization reaction to generate carbonate precipitates, and removing the carbonate precipitates through solid-liquid separation to obtain decarburization liquid, wherein the reaction equation of the decarburization reaction is as follows:
R2CO3+CaO+H2O→CaCO3↓+2ROH
R2CO3+Ca(OH)2→CaCO3↓+2ROH
R2CO3+BaO+H2O→BaCO3↓+2ROH
R2CO3+Ba(OH)2→BaCO3↓+2ROH
R——Na、K
5) Adjusting the free base content: removing ammonia gas from the decarbonizing liquid obtained in the step 4) and HCN entering an absorber II in the step 2), and performing absorption reaction in the absorber II to obtain high-purity liquid sodium cyanide or potassium cyanide;
6) Tail gas treatment: the tail gas discharged from the absorber I and the absorber II is treated by a tail gas absorption system.
Further, in step 1), the HCN synthesis gas prepared by the angry method refers to a synthesis gas mainly containing HCN, water, ammonia, carbon dioxide, carbon monoxide, hydrogen, nitrogen and other components obtained by catalytic reaction of ammonia, natural gas and air as raw materials; the HCN synthesis gas prepared by the methanol ammoxidation method is synthesis gas which is prepared by taking ammonia, methanol and air as raw materials and carrying out catalytic reaction and mainly contains various components such as HCN, water, ammonia, carbon dioxide, carbon monoxide, hydrogen, nitrogen and the like.
Further, in step 1), the temperature of HCN ammonia removal after ammonia removal and cooling is 0 to 90 ℃.
Further, in step 1), the temperature of HCN ammonia removal after ammonia removal and cooling is 30 to 70 ℃.
Further, in step 2), the ammonia removal of HCN entering the absorber I accounts for 65% -98% of the total volume of HCN ammonia removal.
In step 3), the absorption reaction of HCN ammonia removal in the absorber I is continuous absorption reaction, the reaction temperature is 25-70 ℃, the process is cyclic absorption, namely, a small part of the reaction liquid is extracted to be used as a crude cyanide solution for decarbonization reaction, and most of the reaction liquid is used as a circulating liquid, and the circulating liquid is mixed with a fresh sodium hydroxide or potassium hydroxide solution which is continuously added to form an alkaline absorption liquid and then is sent into the absorber I for absorption reaction; the mass ratio of the circulating liquid to the extracted crude cyanide solution is 2-30: 1, wherein the concentration of the sodium hydroxide or potassium hydroxide solution is set to 20-50 wt%.
Further, the mass ratio of the circulating liquid to the extracted crude cyanide solution is 3-15: 1, wherein the concentration of the sodium hydroxide or potassium hydroxide solution is set to 25-45 wt%.
In step 5), the absorption reaction of HCN ammonia removal in the absorber II is continuous absorption reaction, the reaction temperature is 25-70 ℃, the process is cyclic absorption, namely, a small part of the reaction liquid is extracted to obtain a high-purity liquid sodium cyanide or potassium cyanide product, and most of the reaction liquid is taken as a circulating liquid, and the circulating liquid is mixed with a continuously added decarburization liquid to form an absorption liquid and then is sent into the absorber II for absorption reaction; the mass ratio of the circulating liquid to the extracted product liquid is 1-20: 1.
in step 5), the liquid obtained by the absorption reaction in the absorber II is added with calcium oxide, calcium hydroxide, barium oxide or barium hydroxide or a mixture thereof again for decarburization reaction, and the high-purity liquid sodium cyanide or potassium cyanide product with low carbonate and formate content and satisfactory free alkali is obtained after solid-liquid separation and precipitation.
Further, the molar ratio of the calcium oxide, the calcium hydroxide, the barium oxide or the barium hydroxide added in the decarburization reaction to the carbonate in the cyanide solution is 0.8-1: 1, preferably 0.9 to 1:1.
the invention also discloses a production device for preparing high-purity sodium cyanide or potassium cyanide with high yield, which comprises an ammonia removal system, an absorber I, an absorber II and a tail gas absorption system, wherein a gas phase outlet of the ammonia removal system is connected with gas phase inlets of the absorber I and the absorber II, a gas phase outlet of the absorber I and a gas phase inlet of the tail gas absorption system are connected, a liquid phase outlet of the absorber I is sequentially connected with a decarburization reactor I, a solid-liquid separator I and a liquid phase inlet of the absorber II, a liquid phase outlet I of the absorber II is connected with a high-purity sodium cyanide or potassium cyanide collecting tank, a tail gas absorption liquid outlet of the tail gas absorption system is connected with a liquid phase inlet of the absorber I, and a liquid phase outlet II of the absorber II is sequentially connected with a decarburization reactor II, a solid-liquid separator II and the high-purity sodium cyanide or potassium cyanide collecting tank.
The invention has the beneficial effects that:
1. the invention provides a production process and a production device for preparing high-purity sodium cyanide or potassium cyanide with high yield, which can prepare high-purity liquid sodium cyanide or potassium cyanide with low carbonate and formate content and satisfactory free alkali content by an Ann method or a methanol ammoxidation method without purification, wherein the carbonate content can be controlled to be less than or equal to 0.40wt%; the formate content can be controlled to be less than or equal to 0.10wt%; the content of hydroxide (free alkali) can be controlled between 0.1wt% and 0.9wt%; the product has good color, is colorless and transparent; the content of sodium cyanide or potassium cyanide in the product liquid can be effectively controlled to be 20-45 wt%, and can be flexibly adjusted according to the needs; because the HCN synthesis gas is subjected to an ammonia removal process to remove ammonia in the synthesis gas, the synthesis gas is further cooled, so that the reaction temperature can be effectively controlled without a large amount of circulating liquid in the absorption reaction, the inhibition of side reactions of formate and ammonia generated by cyanide thermal decomposition is realized, and ammonia can be avoided in the prepared liquid sodium cyanide or potassium cyanide product.
2. The invention provides a production process and a production device for preparing high-purity sodium cyanide or potassium cyanide in high yield, which are difficult to avoid a small amount of unreacted methanol in HCN synthesis gas prepared by ammoxidation of methanol.
3. The process and the device for preparing high-purity sodium cyanide or potassium cyanide with high yield provided by the invention adopt the process of firstly removing ammonia and cooling HCN synthetic gas, more than 70% of water in the synthetic gas can be removed in advance, and compared with the technologies of patent CN102502708 and US2616782, the process and the device avoid that the partial water is taken into liquid sodium cyanide or potassium cyanide products to produce products with the same concentration, and can adopt alkali with lower concentration as raw materials; because the evaporation concentration of the liquid sodium cyanide or potassium cyanide for producing the solid sodium cyanide or potassium cyanide generally needs to be controlled under high vacuum and the temperature is below 50 ℃, the energy consumption is greatly increased when the liquid sodium cyanide or potassium cyanide with low concentration is used for producing the solid product.
4. The production process and the production device for preparing the high-purity sodium cyanide or potassium cyanide with high yield separate the processes of synthesizing cyanide and decarbonizing added lime, compared with the synchronous process of the two processes of patent US2616782, the production process and the production device avoid the problem that the added lime and the generated calcium carbonate precipitate block an absorption reactor; the amount of lime added in decarburization does not exceed the amount of carbonate in the feed liquid, and compared with patent US2616782, the method requires equal amount or large excess, reduces lime consumption and avoids the residue of calcium ions in the feed liquid.
5. The production process and the production device for preparing high-purity sodium cyanide or potassium cyanide with high yield provided by the invention have single product, and compared with the patent CN102502708, a small amount of hydroxy acetonitrile is required to be co-produced, so that the investment is greatly saved, and the energy consumption is reduced.
6. The production process and the production device for preparing the high-purity sodium cyanide or potassium cyanide with high yield adopt the liquid sodium cyanide or potassium cyanide produced by the HCN synthesis gas without purification treatment, the product quality can completely reach the same level of adopting the purified liquid hydrocyanic acid as the raw material, but the loss in the purification process is avoided, and the yield is greatly improved; compared with the patents CN102502708 and US2616782, the absorption reaction can be carried out at a lower temperature, and the side reaction of cyanide generated into formate by pyrolysis is effectively inhibited, so that the yield is higher.
Drawings
FIG. 1 is a block flow diagram of a process for producing high purity sodium cyanide or potassium cyanide in high yield according to the present invention.
Reference numerals: 1-an ammonia removal system; 2-absorber I; 3-absorber II; 4-an exhaust gas absorption system; a 5-decarbonization reactor I; 6-a solid-liquid separator I; 7-decarbonization reactor II; 8-a solid-liquid separator II.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
The HCN synthesis gas prepared by the Ann method adopted in the following examples refers to synthesis gas which is prepared by taking ammonia, natural gas and air as raw materials and is prepared by catalytic reaction and mainly contains a plurality of components such as HCN, water, ammonia, carbon dioxide, carbon monoxide, hydrogen, nitrogen and the like;
the HCN synthesis gas prepared by the methanol ammoxidation method is synthesis gas which is prepared by taking ammonia, methanol and air as raw materials and is mainly composed of a plurality of components such as HCN, water, ammonia, carbon dioxide, carbon monoxide, hydrogen, nitrogen and the like through catalytic reaction;
the absorber I and absorber II employed in the examples below are absorber towers, falling film absorbers, microreactors, pipe static mixers or mixing reactors filled with structured packing;
the tail gas absorption system in the following embodiments is an absorption tower or a falling film absorber;
the manner of solid-liquid separation in the following examples is centrifugation, filtration, sedimentation or a combination thereof;
in the following examples, the tail gas discharged from the absorber I and the absorber II was used for the tail gas treatment, and the tail gas was incinerated after the tail gas absorption system was subjected to reabsorption treatment with sodium hydroxide or potassium hydroxide solution.
FIG. 1 is a block flow diagram of the process of the present invention for producing high purity sodium cyanide or potassium cyanide in high yields;
example 1
In an industrial reaction device, the composition content of HCN synthesis gas prepared by an Ann method by taking natural gas, ammonia and air as raw materials is analyzed as follows:
| component (A) | CH4 | NH3 | O2 | H2 | N2 | CO | CO2 | H2O | HCN |
| Volume fraction (%) | 0.894 | 1.838 | 0.195 | 7.278 | 53.335 | 3.877 | 0.156 | 24.513 | 7.915 |
The ammonia in the synthesis gas is removed by sulfuric acid absorption in an ammonia removal system, and the synthesis gas is cooled to 40 ℃ to obtain HCN ammonia removal gas, and the component content analysis is as follows:
| component (A) | CH4 | O2 | H2 | N2 | CO | CO2 | H2O | HCN |
| Volume fraction (%) | 1.153 | 0.251 | 9.379 | 68.732 | 4.187 | 0.201 | 5.946 | 9.342 |
The HCN ammonia removal is divided into two parts, wherein the first part accounts for 90% of the total volume flow of the HCN ammonia removal, the HCN ammonia removal enters an absorber I, 32% liquid sodium hydroxide is used for continuous cyclic absorption at 40 ℃, the mass ratio of the circulating liquid to the extracted crude sodium cyanide solution is 18:1, and the component content of the extracted crude sodium cyanide solution is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 28.475 | 2.028 | 1.324 | 0.024 | 68.150 |
Adding the extracted crude sodium cyanide solution into a decarbonization kettle for decarbonization reaction, wherein the molar ratio of the added calcium hydroxide to carbonate in the crude sodium cyanide solution is 0.95:1, filtering the feed liquid treated by decarbonization reaction to remove generated calcium carbonate, and obtaining decarbonization liquid, wherein the component content of the decarbonization liquid is analyzed in the following table:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 28.316 | 2.961 | 0.067 | 0.024 | 68.633 |
In absorber II, the ammonia gas is removed by continuously and circularly absorbing another part of HCN at 35 ℃ by using decarbonization liquid, the mass ratio of the recycle liquid to the extracted high-purity sodium cyanide product liquid is 2:1, and the component content of the extracted high-purity sodium cyanide product liquid is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 30.917 | 0.236 | 0.211 | 0.072 | 68.564 |
Tail gas from the gas phase outlets of the absorber I and the absorber II enters a tail gas absorption tower, 32% liquid sodium hydroxide is used for absorption, the HCN content in the gas phase outlet of the tail gas absorption tower is lower than 5ppm, and absorption liquid from the bottom of the tail gas absorption tower is used for the absorber I.
The high-purity liquid sodium cyanide with low carbonate and formate content and satisfactory free alkali content is prepared in the embodiment, wherein the carbonate content is 0.15-0.30wt%; the formate content is 0.06-0.08 wt%; the content of hydroxide (free alkali) can be controlled between 0.2wt% and 0.5wt%; the product has good color, is colorless and transparent; the sodium cyanide content in the product liquid is 29-32 wt%.
Example 2
In an industrial reaction device, the composition content of HCN synthesis gas prepared by an Ann method by taking natural gas, ammonia and air as raw materials is analyzed as follows:
the ammonia in the synthesis gas is removed by sulfuric acid absorption in an ammonia removal system, and the synthesis gas is cooled to 45 ℃ to obtain HCN ammonia removal gas, and the component content analysis is as follows:
| component (A) | CH4 | O2 | H2 | N2 | CO | CO2 | H2O | HCN |
| Volume fraction (%) | 1.155 | 0.251 | 9.397 | 68.868 | 4.195 | 0.201 | 5.761 | 9.361 |
The HCN ammonia removal is divided into two parts, wherein the first part accounts for 75% of the total volume flow of the HCN ammonia removal, the HCN ammonia removal enters an absorber I, 32% liquid sodium hydroxide is used for continuous cyclic absorption at 40 ℃, the mass ratio of the circulating liquid to the extracted crude sodium cyanide solution is 10:1, and the component content of the extracted crude sodium cyanide solution is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 24.151 | 6.488 | 1.123 | 0.024 | 68.213 |
Adding the extracted crude sodium cyanide solution into a decarbonization kettle for decarbonization reaction, wherein the molar ratio of the added calcium hydroxide to carbonate in the crude sodium cyanide solution is 0.99:1, filtering the feed liquid treated by decarbonization reaction to remove generated calcium carbonate, and obtaining decarbonization liquid, wherein the component content of the decarbonization liquid is analyzed in the following table:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 24.002 | 7.274 | 0.023 | 0.024 | 68.677 |
In absorber II, the ammonia gas is removed by continuously and circularly absorbing another part of HCN at 40 ℃, the mass ratio of the circulating liquid to the extracted high-purity sodium cyanide product liquid is 8:1, and the component content of the extracted high-purity sodium cyanide product liquid is analyzed as follows:
tail gas from the gas phase outlets of the absorber I and the absorber II enters a tail gas absorption tower, 32% liquid sodium hydroxide is used for absorption, the HCN content in the gas phase outlet of the tail gas absorption tower is lower than 5ppm, and absorption liquid from the bottom of the tail gas absorption tower is used for the absorber I.
The high-purity liquid sodium cyanide with low carbonate and formate content and satisfactory free alkali content is prepared by the embodiment, wherein the carbonate content is 0.30-0.40 wt%; the formate content is 0.06-0.08 wt%; the content of hydroxide (free alkali) can be controlled between 0.2wt% and 0.5wt%; the product has good color, is colorless and transparent; the sodium cyanide content in the product liquid is 29-31 wt%.
Example 3
In an industrial reaction device, the composition content of HCN synthesis gas prepared by an Ann method by taking natural gas, ammonia and air as raw materials is analyzed as follows:
| component (A) | CH4 | NH3 | O2 | H2 | N2 | CO | CO2 | H2O | HCN |
| Volume fraction (%) | 0.894 | 1.838 | 0.195 | 7.278 | 53.335 | 3.877 | 0.156 | 24.513 | 7.915 |
The ammonia in the synthesis gas is removed by sulfuric acid absorption in an ammonia removal system, and the synthesis gas is cooled to 40 ℃ to obtain HCN ammonia removal gas, and the component content analysis is as follows:
| component (A) | CH4 | O2 | H2 | N2 | CO | CO2 | H2O | HCN |
| Volume fraction (%) | 1.153 | 0.251 | 9.379 | 68.732 | 4.187 | 0.201 | 5.946 | 9.342 |
The HCN ammonia removal is divided into two parts, wherein the first part accounts for 30% of the total volume flow of the HCN ammonia removal, the HCN ammonia removal enters an absorber I, the HCN ammonia removal is continuously and circularly absorbed by 32% liquid sodium hydroxide at 40 ℃, the mass ratio of circulating liquid to the extracted crude sodium cyanide solution is 5:1, and the component content of the extracted crude sodium cyanide solution is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 10.363 | 20.703 | 0.482 | 0.026 | 68.426 |
Adding the extracted crude sodium cyanide solution into a decarbonization kettle for decarbonization reaction, wherein the molar ratio of the added calcium hydroxide to carbonate in the crude sodium cyanide solution is 0.98:1, filtering the feed liquid treated by decarbonization reaction to remove generated calcium carbonate, and obtaining decarbonization liquid, wherein the component content of the decarbonization liquid is analyzed in the following table:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 10.274 | 20.880 | 0.010 | 0.026 | 68.810 |
In absorber II, another part of HCN is continuously and circularly absorbed at 40 ℃ to remove ammonia gas, the mass ratio of the circulating liquid to the extracted sodium cyanide solution is 12:1, and the component content of the extracted sodium cyanide solution is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 30.393 | 0.110 | 1.003 | 0.070 | 68.424 |
Adding the sodium cyanide solution from the absorber II into a decarbonization kettle II for decarbonization treatment, wherein the molar ratio of the added calcium hydroxide to carbonate in the sodium cyanide solution is 0.85:1, filtering the feed liquid subjected to decarbonization reaction to remove generated calcium carbonate, and obtaining high-purity sodium cyanide product liquid, wherein the component content of the high-purity sodium cyanide product liquid is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 30.176 | 0.748 | 0.149 | 0.070 | 68.856 |
Tail gas from the gas phase outlets of the absorber I and the absorber II enters a tail gas absorption tower, 32% liquid sodium hydroxide is used for absorption, the HCN content in the gas phase outlet of the tail gas absorption tower is lower than 5ppm, and absorption liquid from the bottom of the tail gas absorption tower is used for the absorber I.
The high-purity liquid sodium cyanide with low carbonate and formate content and satisfactory free alkali content is prepared in the embodiment, wherein the carbonate content is 0.10-0.20wt%; the formate content is 0.06-0.09 wt%; the content of hydroxide (free alkali) can be controlled between 0.6wt% and 0.8wt%; the product has good color, is colorless and transparent; the sodium cyanide content in the product liquid is 29-31 wt%.
Example 4
In an industrial reaction device, methanol, ammonia and air are used as raw materials to prepare HCN by a methanol ammoxidation method
Synthesis gas, the component content of which is analyzed in the following table:
| component (A) | CH3OH | NH3 | O2 | H2 | N2 | CO | CO2 | H2O | HCN |
| Volume fraction (%) | 0.72 | 1.79 | 1.05 | 8.42 | 57.43 | 1.45 | 1.01 | 21.35 | 6.78 |
The ammonia in the synthesis gas is removed by sulfuric acid absorption in an ammonia removal system, and the synthesis gas is cooled to 40 ℃ to obtain HCN ammonia removal gas, and the component content analysis is as follows:
| component (A) | O2 | H2 | N2 | CO | CO2 | H2O | HCN |
| Volume fraction (%) | 1.320 | 10.588 | 72.219 | 1.823 | 1.270 | 4.970 | 7.809 |
The HCN ammonia removal is divided into two parts, wherein the first part accounts for 85 percent of the total volume flow of the HCN ammonia removal, the HCN ammonia removal enters an absorber I, 35 percent liquid sodium hydroxide is used for continuous cyclic absorption at 40 ℃, the mass ratio of the circulating liquid to the extracted crude sodium cyanide solution is 15:1, and the component content of the extracted crude sodium cyanide solution is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 29.067 | 3.824 | 1.351 | 0.024 | 65.734 |
Adding the extracted crude sodium cyanide solution into a decarbonization kettle for decarbonization reaction, wherein the molar ratio of the added calcium hydroxide to carbonate in the crude sodium cyanide solution is 0.97:1, filtering the feed liquid treated by decarbonization reaction to remove generated calcium carbonate, and obtaining decarbonization liquid, wherein the component content of the decarbonization liquid is analyzed in the following table:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 28.923 | 4.799 | 0.027 | 0.023 | 66.227 |
In absorber II, continuously and circularly absorbing another part of HCN at 40 ℃ to remove ammonia gas, wherein the mass ratio of the circulating liquid to the extracted high-purity sodium cyanide product liquid is 3:1, and the component content of the extracted high-purity sodium cyanide product liquid is analyzed as follows:
| component (A) | NaCN | NaOH | Na2CO3 | HCOONa | H2O |
| Mass fraction (%) | 33.109 | 0.375 | 0.261 | 0.052 | 66.203 |
Tail gas from the gas phase outlets of the absorber I and the absorber II enters a tail gas absorption tower, 35% liquid sodium hydroxide is used for absorption, the HCN content in the gas phase outlet of the tail gas absorption tower is lower than 5ppm, and absorption liquid from the bottom of the tail gas absorption tower is used for the absorber I.
The high-purity liquid sodium cyanide with low carbonate and formate content and satisfactory free alkali content is prepared by the embodiment, wherein the carbonate content is 0.20-0.30wt%; the formate content is 0.04 to 0.07 weight percent; the content of hydroxide (free alkali) can be controlled between 0.2wt% and 0.5wt%; the product has good color, is colorless and transparent; the sodium cyanide content in the product liquid is 32-34 wt%.
The invention also discloses a production device for preparing high-purity sodium cyanide or potassium cyanide with high yield, which comprises an ammonia removal system 1, an absorber I2, an absorber II3 and a tail gas absorption system 4, wherein a gas phase outlet of the ammonia removal system is connected with gas phase inlets of the absorber I and the absorber II, gas phase outlets of the absorber I and the absorber II are connected with gas phase inlets of the tail gas absorption system, a liquid phase outlet of the absorber I is sequentially connected with a decarburization reactor I5, a solid-liquid separator I6 and a liquid phase inlet of the absorber II, a liquid phase outlet I of the absorber II is connected with a high-purity sodium cyanide or potassium cyanide collecting tank, a tail gas absorption liquid outlet of the tail gas absorption system is connected with a liquid phase inlet of the absorber I, and a liquid phase outlet II of the absorber II is sequentially connected with a decarburization reactor II7, a solid-liquid separator II8 and a high-purity sodium cyanide or potassium cyanide collecting tank.
Finally, it is noted that the above-mentioned preferred embodiments are only intended to illustrate rather than limit the invention, and that, although the invention has been described in detail by means of the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.
Claims (9)
1. A production process for preparing high-purity sodium cyanide or potassium cyanide with high yield is characterized in that: the method comprises the following steps:
1) Removing ammonia and cooling: the ammonia in the HCN synthesis gas is removed from the HCN synthesis gas prepared by an Ann method or a methanol ammoxidation method in an ammonia removal system through sulfuric acid or phosphoric acid absorption, and the HCN synthesis gas is cooled to obtain HCN ammonia removal gas;
2) HCN ammonia removal split stream: the HCN ammonia removal obtained in the step 1) is divided into 2 parts, and the 2 parts enter an absorber I and an absorber II respectively, the HCN ammonia removal in the absorber I accounts for 10% -98% of the total volume flow of the HCN ammonia removal, and the rest parts enter the absorber II;
3) Absorption reaction: the HCN ammonia gas entering the absorber I is removed, and the HCN ammonia gas and sodium hydroxide or potassium hydroxide solution are subjected to absorption reaction to obtain a crude cyanide solution;
4) Decarburization reaction: adding calcium oxide, calcium hydroxide, barium oxide or barium hydroxide or a mixture thereof into the crude cyanide solution extracted from the absorber I to perform decarburization reaction to generate carbonate precipitates, and removing the carbonate precipitates through solid-liquid separation to obtain decarburization liquid, wherein the reaction equation of the decarburization reaction is as follows:
R 2 CO 3 +CaO+H 2 O→CaCO 3 ↓+2ROH
R 2 CO 3 +Ca(OH) 2 →CaCO 3 ↓+2ROH
R 2 CO 3 +BaO+H 2 O→BaCO 3 ↓+2ROH
R 2 CO 3 +Ba(OH) 2 →BaCO 3 ↓+2ROH
R——Na、K
5) Adjusting the free base content: removing ammonia gas from the decarbonizing liquid obtained in the step 4) and HCN entering an absorber II in the step 2), and performing absorption reaction in the absorber II to obtain high-purity liquid sodium cyanide or potassium cyanide;
in the step 1), the HCN synthesis gas prepared by the ambergris method is synthesis gas mainly containing multiple components of HCN, water, ammonia, carbon dioxide, carbon monoxide, hydrogen and nitrogen, which is obtained by catalytic reaction of ammonia, natural gas and air as raw materials; the HCN synthesis gas prepared by the methanol ammoxidation method is synthesis gas which is prepared by taking ammonia, methanol and air as raw materials and carrying out catalytic reaction and mainly contains a plurality of components of HCN, water, ammonia, carbon dioxide, carbon monoxide, hydrogen and nitrogen.
2. The process for producing high purity sodium cyanide or potassium cyanide in high yield according to claim 1, wherein: in step 1), the temperature of the HCN ammonia removal after ammonia removal and cooling is 0-90 ℃.
3. The process for producing high purity sodium cyanide or potassium cyanide in high yield according to claim 2, wherein: in step 1), the ammonia removal temperature of HCN after ammonia removal and cooling is 30-70 ℃.
4. The process for producing high purity sodium cyanide or potassium cyanide in high yield according to claim 1, wherein: in the step 2), the ammonia removal of HCN entering the absorber I accounts for 65% -98% of the total volume of the ammonia removal of HCN.
5. The process for producing high purity sodium cyanide or potassium cyanide in high yield according to claim 1, wherein: in the step 3), the absorption reaction of removing ammonia from HCN in the absorber I is continuous absorption reaction, the reaction temperature is 25-70 ℃, the process is cyclic absorption, namely, a small part of the reaction liquid is extracted to be used as a crude cyanide solution for decarbonization reaction, and most of the reaction liquid is used as a circulating liquid, and the circulating liquid is mixed with a fresh sodium hydroxide or potassium hydroxide solution which is continuously added to form an alkaline absorption liquid and then is sent into the absorber I for absorption reaction; the mass ratio of the circulating liquid to the extracted crude cyanide solution is 2-30: 1, wherein the concentration of the sodium hydroxide or potassium hydroxide solution is set to 20-50 wt%.
6. The process for producing high purity sodium cyanide or potassium cyanide in high yield according to claim 5, wherein: the mass ratio of the circulating liquid to the extracted crude cyanide solution is 3-15: 1, wherein the concentration of the sodium hydroxide or potassium hydroxide solution is set to 25-45 wt%.
7. The process for producing high purity sodium cyanide or potassium cyanide in high yield according to claim 1, wherein: in the step 5), the absorption reaction of the HCN ammonia removal in the absorber II is continuous absorption reaction, the reaction temperature is 25-70 ℃, the process is cyclic absorption, namely, a small part of the reaction liquid is extracted to obtain a high-purity liquid sodium cyanide or potassium cyanide product, and most of the reaction liquid is taken as a circulating liquid, and the circulating liquid is mixed with a continuously added decarburization liquid to form an absorption liquid and then is sent into the absorber II for absorption reaction; the mass ratio of the circulating liquid to the extracted product liquid is 1-20: 1.
8. the process for producing high purity sodium cyanide or potassium cyanide in high yield according to claim 1, wherein: in the step 5), the feed liquid obtained by the absorption reaction in the absorber II is added with calcium oxide, calcium hydroxide, barium oxide or barium hydroxide or a mixture thereof again for decarburization reaction, and the high-purity liquid sodium cyanide or potassium cyanide product with low carbonate and formate content and satisfactory free alkali is obtained after solid-liquid separation and precipitation.
9. A process for producing high purity sodium cyanide or potassium cyanide in high yield as claimed in any one of claims 1 and 8, wherein: the molar ratio of the calcium oxide, the calcium hydroxide, the barium oxide or the barium hydroxide added in the decarbonization reaction to the carbonate in the cyanide solution is 0.8-1: 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011608277.4A CN113044857B (en) | 2020-12-30 | 2020-12-30 | Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011608277.4A CN113044857B (en) | 2020-12-30 | 2020-12-30 | Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113044857A CN113044857A (en) | 2021-06-29 |
| CN113044857B true CN113044857B (en) | 2023-05-23 |
Family
ID=76508445
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011608277.4A Active CN113044857B (en) | 2020-12-30 | 2020-12-30 | Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113044857B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115818668B (en) * | 2022-10-27 | 2024-06-25 | 万华化学集团股份有限公司 | Method for preparing hydrocyanic acid by ammoxidation of methanol |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1032148A (en) * | 1987-09-24 | 1989-04-05 | 纳幕尔杜邦公司 | The production method of sodium cyanide |
| CN1699174A (en) * | 2005-05-10 | 2005-11-23 | 长春黄金研究院 | Method for regenerating sodium cyanide from solutions containing cyanogen and thiocyanate |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE801722C (en) * | 1949-01-01 | 1951-01-22 | Degussa | Process for the production of barium cyanide from barium hydroxide and hydrocyanic acid |
| JPS49109292A (en) * | 1973-02-21 | 1974-10-17 | ||
| CA1318480C (en) * | 1988-10-21 | 1993-06-01 | Adrian J. Goldstone | Cyanide regeneration process |
| US5254153A (en) * | 1988-10-21 | 1993-10-19 | Cyprus Minerals Company | Cyanide recycling process |
| US5538604A (en) * | 1995-01-20 | 1996-07-23 | Emec Consultants | Suppression of cyanide formation in electrolytic cell lining |
| US6896863B2 (en) * | 2003-04-01 | 2005-05-24 | E. I. Du Pont De Nemours And Company | Sodium cyanide process |
| WO2006099252A1 (en) * | 2005-03-11 | 2006-09-21 | Nevada Chemicals, Inc. | Producing calcium cyanide at a mine site using easily transportable starting materials |
| DE102011075595A1 (en) * | 2011-05-10 | 2012-11-15 | Evonik Degussa Gmbh | Process for the production of carbon fibers |
| CN102502708B (en) * | 2011-10-21 | 2013-11-13 | 重庆紫光天化蛋氨酸有限责任公司 | Preparation method for preparing alkali metal or alkali earth metal cyanide with high purity and high yield |
| CN104245678B (en) * | 2012-06-28 | 2016-02-24 | 隆萨有限公司 | The method of medetomidine is prepared with monochloroacetone |
| CN104724724B (en) * | 2014-11-21 | 2017-01-04 | 枣阳市金鹿化工有限公司 | A kind of combine the process preparing liquid hydrocyanic acid and Cyanogran. |
| CA2941223C (en) * | 2015-09-21 | 2018-09-25 | Veolia Water Solutions & Technologies Support | Method for recovering cyanide from a barren solution |
| CN107841622A (en) * | 2017-11-10 | 2018-03-27 | 陈鹏 | A kind of method of cyanidation tailings comprehensive utilization and harmless treatment |
| CN110484719B (en) * | 2019-09-27 | 2021-05-14 | 西安建筑科技大学 | Pretreatment carbonaceous gold concentrate, preparation method thereof and gold extraction method |
| CN111484039A (en) * | 2020-03-24 | 2020-08-04 | 营口德瑞化工有限公司 | Method for removing sodium/potassium carbonate and sodium/potassium hydroxide in sodium cyanide/potassium solution |
-
2020
- 2020-12-30 CN CN202011608277.4A patent/CN113044857B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1032148A (en) * | 1987-09-24 | 1989-04-05 | 纳幕尔杜邦公司 | The production method of sodium cyanide |
| CN1699174A (en) * | 2005-05-10 | 2005-11-23 | 长春黄金研究院 | Method for regenerating sodium cyanide from solutions containing cyanogen and thiocyanate |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113044857A (en) | 2021-06-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102502708B (en) | Preparation method for preparing alkali metal or alkali earth metal cyanide with high purity and high yield | |
| CN108046295B (en) | Method for producing sodium bicarbonate and ammonium sulfate by using sodium sulfate solution | |
| CN113135582A (en) | Production method for jointly preparing sodium carbonate and ammonium chloride by using sodium chloride | |
| US4053507A (en) | Method of recovering unreacted materials and heat in urea synthesis | |
| CN108975356B (en) | Method for producing sodium bicarbonate and ammonium sulfate from sodium sulfate and/or mirabilite | |
| CN109503312B (en) | Process for continuously producing chloroethane by using byproduct hydrogen chloride produced in chlorobenzene production | |
| US3116294A (en) | Process- for preparing high-purity melamine from urea | |
| CN111825538B (en) | Method for continuously producing pseudo ionone | |
| CN101519383B (en) | Process for jointly producing cyanuramide, sodium carbonate and ammonium chloride by using carbamide | |
| CN112225235A (en) | Method for preparing sodium bicarbonate and sodium bisulfate from sodium sulfate | |
| CN102198953A (en) | Methods for coproducing sodium carbonate and ammonium sulfate from melamine tail gas and mirabilite | |
| CN114436297A (en) | Method for preparing sodium carbonate from mirabilite | |
| CN113044857B (en) | Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield | |
| CN101333197A (en) | Method for producing melamine and co-producing ammine and ammonium hydrogen carbonate | |
| CN104910031A (en) | Method for co-producing glycine and hydantoin, and apparatus thereof | |
| EP3416953B1 (en) | Method for revamping a high pressure melamine plant | |
| US3619132A (en) | Process for the production of alkali cyanides | |
| WO1994018360A1 (en) | Process for recovering solid sodium bicarbonate from diaphragm cell | |
| CN217398465U (en) | Production device for preparing high-purity sodium cyanide or potassium cyanide with high yield | |
| AU2006244735B2 (en) | Method for concentrating an aqueous ammonium carbamate stream | |
| US3193353A (en) | Method of removing carbon dioxide from ammonia | |
| RU2454403C1 (en) | Method of producing carbamide | |
| CN105084328A (en) | Method for producing ammonium sulfamate by utilization of exhaust gas containing ammonia and carbon dioxide | |
| CN114455612A (en) | Novel process for preparing soda ash byproduct gypsum by using sodium sulfate and carbon dioxide as raw materials | |
| US3470247A (en) | Process for the production of urea by synthesis of ammonia and carbon dioxide,with total recycling of the portion which has not been converted into urea |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |