CN1974388A - Sodium carbonate preparing process - Google Patents

Abstract

The present invention is ammonia-nickel process for preparing sodium carbonate, and the process has facile material, low medium ammonia and nickel loss, reuse of medium ammonia and nickel, less pollutant exhaustion and high product quality with chlorine content controlled within 0.1 %. The preparation process includes the following steps: dissolving NiO in the mixture solution of CO2 and ammonia to absorb ammonia to saturation, adding NaCl for metathesis, filtering to separate ammonia water solution of Na2CO3 and Ni(NH3)6Cl2, distilling ammonia water solution of Na2CO3 to eliminate ammonia, filtering to obtain precipitate Ni2(OH)2CO3, concentrating the filtrate to crystallize sodium carbonate product, heating Ni(NH3)6Cl2 to eliminate ammonia and obtain NiCl2, heating NiCl2 to react with water vapor to obtain NiO and mixture of HCl and water vapor, recovering NiO, condensating the mixture of HCl and water vapor to obtain hydrochloric acid and mixing Cl2 and air to obtain liquid chlorine.

Description

Preparation method of sodium carbonate

Technical Field

The invention relates to a carbonate of sodium, potassium or general alkalimetal, in particular to a process for preparing calcined soda by adopting an ammonia nickel method.

Background

The traditional alkali making process mainly comprises an ammonia-soda process, a combined-soda process and a natural alkali refining process, wherein the ammonia-soda process has the advantages of easily obtained raw materials, mature and simple process, low utilization rate of NaCl and simultaneously generation of a large amount of waste liquid. The combined alkali method solves the problems existing in the ammonia-soda method, but has higher equipment requirement and by-product NH₄Cl as a fertilizerIs limited abroad, is limited by the market price of other nitrogen fertilizers at home, and has low added value.

Plum loyalty in the invention patent application with publication number CN1308020 provides a new soda production process by adding CaCl in ammonia distillation mother liquor₂And converting into CaO again, and returning to the ammonia distillation system. So as to thoroughly eliminate a large amount of waste liquid and waste residue in the ammonia-soda process soda production and reduce the consumption. The theory is as follows: 。

xugui in the invention patent application with publication No. CN1814548 provides a process for producing soda by ammonia-soda process without waste discharge, which is to treat the waste residue liquid from the ammonia evaporation process, separate the waste residue liquid by the separation process to remove the slag and wash the slag to obtain the engineering soil product; reacting the supernatant with frozen nitre (Na2SO4) in a reaction process to obtain a refined gypsum product; the circulating liquid from the reaction process enters a brine process for recycling; and the redundant circulating liquid enters a salt making procedure to prepare a refined salt product.

Disclosure of Invention

The invention aims to solve the problems of the existing alkali making process and provide a method for preparing sodium carbonate, which has the advantages of easily available raw materials, low loss of medium ammonia and nickel, cyclic utilization, no waste generation in the middle, low discharge capacity, high quality of prepared target products and controllable chlorine content within 0.1%.

The technical scheme of the invention is that NaCl and industrial CO are used₂Water and air as raw materials, and ammonia and nickel as media to prepare soda ash and hydrochloric acid or chlorine.

The invention comprises the following steps:

1) dissolving NiO in CO₂Adding ammonia into the mixed solution of the sodium chloride and ammonia water, absorbing ammonia until the mixed solution is saturated, adding NaCl for double decomposition, filtering and separating Na₂CO₃Aqueous ammonia solution and Ni (NH)₃)₆Cl₂；

2) Mixing Na₂CO₃Distilling ammonia water solution to remove ammonia, filtering out precipitate Ni₂(OH)₂CO₃Concentrating and crystallizing the filtrate to obtain a soda ash product;

3) mixing Ni (NH)₃)₆Cl₂Heating to 150-200 ℃ and deaminizing to obtain NiCl₂；

4) Mixing NiCl₂Heating to 500-1000 ℃, reacting with water vapor to obtain NiO and a mixture of hydrogen chloride and water vapor, or reacting with O in the air₂Reacting to obtain NiO and Cl₂Mixing with air, recovering NiO to the leaching step in step 1 for recycling, and condensing the mixture of hydrogen chloride and water vapor to obtain hydrochloric acid product, Cl₂The mixed gas with air is separated into liquid chlorine product by freezing.

NiO and CO in a mass ratio₂∶NaCl＝100∶62∶162，NiCl₂100: 200 of water vapor.

The basic principle of the invention is as follows: because NiO is easily dissolved in (NH)₄)₂CO₃Solution, Ni (NH) can be easily formed₃)₆CO₃Solution of Ni (NH)₃)₆Cl₂The solubility in concentrated ammonia is very low, so that the above characteristics are utilized, and NaCl and Ni (NH) are used₃)₆Cl₂Carrying out double decomposition reaction to obtain Na₂CO₃The chemical reaction formula is as follows:

wherein ammonia and nickel are recycled, and theoretically, the loss in the process is very small.

The invention solves the problems in the existing ammonia-soda process for preparing the sodium carbonate, the needed raw materials are easy to obtain, the loss of medium ammonia and nickel is small, the medium ammonia and nickel can be recycled, no waste is generated in the middle, the discharge capacity is small, the chlorine content of the prepared target product low-chlorine sodium carbonate is less than 0.1 percent, and the byproduct is hydrochloric acid or chlorine.

Detailed Description

The following examples further illustrate the invention.

10kgNiO was dissolved in a solution containing 6.2kgCO₂CO of₂Adding into mixed solution of ammonia water, absorbing ammonia until saturation, adding 16.2kg NaCl for double decomposition, filtering, and separating Na₂CO₃Aqueous ammonia solution and Ni (NH)₃)₆Cl₂(ii) a Mixing Na₂CO₃Distilling ammonia water solution to remove ammonia, filtering out precipitate Ni₂(OH)₂CO₃Concentrating and crystallizing the filtrate to obtain a soda ash product; mixing Ni (NH)₃)₆Cl₂Heating to 150-200 ℃ and deaminizing to obtain NiCl₂(ii) a Mixing NiCl₂Heating to 500-1000 ℃, reacting with water vapor to obtain NiO and a mixture of hydrogen chloride and water vapor, wherein the addition amount of the water vapor is NiCl₂And (2) the NiO is recovered to the leaching process in the step (1) for recycling, and the mixture of the hydrogen chloride and the water vapor is condensed to obtain a hydrochloric acid product.

Claims (5)

1. The preparation method of the soda ash is characterized in that the chemical reaction formula is as follows:

$\mathrm{Ni}{\left({\mathrm{NH}}_3\right)}_6{\mathrm{Cl}}_2\stackrel{\mathrm{\Δ}}{=}{\mathrm{NiCl}}_2+6{\mathrm{NH}}_3\↑$

2. the process for preparing soda ash as claimed in claim 1, wherein the process comprises the steps of:

1) dissolving NiO in CO₂Adding ammonia into the mixed solution of the sodium chloride and ammonia water, absorbing ammonia until the mixed solution is saturated, adding NaCl for double decomposition, filtering and separating Na₂CO₃Aqueous ammonia solution and Ni (NH)₃)₆Cl₂；

2) Mixing Na₂CO₃Distilling ammonia water solution to remove ammonia, filtering out precipitate Ni₂(OH)₂CO₃Concentrating and crystallizing the filtrate to obtain a soda ash product;

NiO and CO in a mass ratio₂∶NaCl＝100∶62∶162。

3. The process for producing soda ash as claimed in claim 2, wherein Ni (NH) is added₃)₆Cl₂Heating to 150-200 ℃ and deaminizing to obtain NiCl₂。

4. The process for preparing soda ash as claimed in claim 2, wherein NiCl is added₂Heating to 500-1000 ℃, reacting with water vapor to obtain NiO and a mixture of hydrogen chloride and water vapor, or reacting with O in the air₂Reacting to obtain NiO and Cl₂Mixing with air, recovering NiO to the leaching step in step 1 for recycling, and condensing the mixture of hydrogen chloride and water vapor to obtain hydrochloric acid product, Cl₂The mixed gas with air is separated into liquid chlorine product by freezing.

5. The process for preparing soda ash as claimed in claim 4, wherein NiCl is added in a mass ratio₂100: 200 of water vapor.