阅读说明：本技术 一种重质纯碱的生产方法 (Production method of heavy soda ash ) 是由 刘宇娜 谢智勇 王松晓 唐晶晶 王建达 丁健 李满枝 于 2021-02-18 设计创作，主要内容包括：本发明公开了一种重质纯碱的生产方法：轻质纯碱和碳酸钠饱和溶液加入水合结晶器；反应后晶浆通入稠厚器调节固液比,稠厚器晶浆进入离心机分离,稠厚器上清液进入母液桶；分离用洗水洗涤,去除晶浆表面盐分及杂质,离心液进入母液桶；离心的固体经处理得到重质纯碱产品；20-50%母液蒸发至碳酸钠和氯化钠共饱点析出一水碳酸钠晶体,一水碳酸钠晶体及蒸汽冷凝液混合回用至水合结晶器,剩余氯化钠及碳酸钠共饱和溶液进入联碱系统真空制盐装置；50-80%母液进入澄清装置,加入硫化钠,去除铁杂质,澄清液进入水合结晶器继续制备重质纯碱。本发明可去除当前重质纯碱生产工艺中重质纯碱母液中氯化钠及铁杂质,减少重质纯碱母液外排,提升重质纯碱产品质量。(The invention discloses a production method of dense soda ash, which comprises the following steps: adding light soda ash and saturated sodium carbonate solution into a hydration crystallizer; after the reaction, introducing the crystal mush into a thickener to adjust the solid-liquid ratio, separating the crystal mush in the thickener by a centrifugal machine, and introducing supernatant of the thickener into a mother liquid barrel; washing with washing water to remove salt and impurities on the surface of the crystal mush, and allowing the centrifugate to enter a mother liquor barrel; treating the centrifuged solid to obtain a heavy soda ash product; evaporating 20-50% of mother liquor to a point where sodium carbonate and sodium chloride are saturated together to separate out sodium carbonate monohydrate crystals, mixing the sodium carbonate monohydrate crystals and the steam condensate for recycling to the hydrated crystallizer, and feeding the residual sodium chloride and sodium carbonate saturated solution into a vacuum salt-making device of an integrated alkali system; 50-80% of mother liquor enters a clarifying device, sodium sulfide is added to remove iron impurities, and the clarified liquor enters a hydration crystallizer to continuously prepare the heavy soda ash. The method can remove sodium chloride and iron impurities in the heavy soda mother liquor in the current heavy soda production process, reduce the discharge of the heavy soda mother liquor and improve the quality of the heavy soda product.)

1. The production method of the heavy soda ash is characterized by comprising the following steps:

(1) adding the light soda ash and the saturated sodium carbonate solution into a hydration crystallizer according to the proportion of 1:0.7-1:1 to perform hydration crystallization reaction for 5-10 minutes;

(2) the solid-liquid ratio of the crystal mush after hydration crystallization is 25-35%, the crystal mush is introduced into a thickener to be adjusted until the solid-liquid ratio is 35-45%, the crystal mush at the bottom outlet of the thickener enters a centrifugal machine for solid-liquid separation, and the supernatant of the thickener enters a mother liquor barrel;

(3) washing water is used for washing in the solid-liquid separation process, and the washing water amount is 180-_{Heavy soda ash}Removing salt and impurities on the surface of the crystal mush, and allowing the centrifugate to enter a mother liquid barrel; calcining, screening and cooling the solid obtained by the centrifugal machine to obtain a heavy soda ash product;

(4) treating 20-50% of heavy soda mother liquor in the mother liquor barrel by using evaporation equipment, evaporating to a point of common saturation of sodium carbonate and sodium chloride to separate out sodium carbonate monohydrate crystals, mixing the sodium carbonate monohydrate crystals and steam condensate for recycling to a hydrated crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate common saturated solution into a vacuum salt-making device of an integrated soda system;

(5) and (3) allowing the heavy soda mother liquor with the volume of 50-80% in the mother liquor barrel to enter a clarifying device, adding sodium sulfide into the clarifying device according to a certain proportion, removing iron impurities in the mother liquor, and allowing the obtained clarified liquor to enter a hydration crystallizer in the original device to continuously prepare the heavy soda.

2. The method for producing soda ash heavy as claimed in claim 1, wherein the ratio of sodium sulfide to soda ash heavy mother liquor in the clarifying device in the step (5) is 5-20mg/L_{Mother liquor of heavy soda ash}。

Technical Field

The invention relates to a production method of soda ash, in particular to a production method of heavy soda ash.

Background

In patent CN02148849.5 "a method for producing dense soda", light soda and saturated solution of sodium carbonate are used as main raw materials, and are hydrated in a hydrated crystallizer for 5-10 minutes according to a certain proportion, the hydrated crystal slurry is fed into a thickener to be thickened, the thickened crystal slurry is fed into a centrifuge for separation, in the separation process, washing water is used to remove salt and impurities on the surface of the solid, the washed solid is fed into a dense soda calciner, and the dense soda is obtained after screening and cooling. Aiming at the problem, a method for removing sodium chloride and iron impurities in the heavy soda ash mother liquor, reducing the discharge of the heavy soda ash mother liquor and improving the quality of the heavy soda ash product is provided.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a production method of heavy soda ash, which can remove sodium chloride and iron impurities in the heavy soda ash mother liquor in the current production process of the heavy soda ash, reduce the discharge of the heavy soda ash mother liquor and improve the quality of the heavy soda ash product.

The purpose of the invention is realized by the following technical scheme.

The production method of the heavy soda ash comprises the following steps:

(1) adding light soda ash and sodium carbonate saturated solution into a hydration crystallizer according to the proportion of 1:0.7-1:1 to carry out hydration crystallization reaction for 5-10 minutes;

(2) the solid-liquid ratio of crystal mush after hydration crystallization according to the prior art is 25-35%, the crystal mush is introduced into a thickener to adjust the solid-liquid ratio to be 35-45%, crystal mush at the bottom outlet of the thickener enters a centrifugal machine for solid-liquid separation, and supernatant of the thickener enters a mother liquor barrel;

(3) washing is carried out by using washing water according to the prior process solid-liquid separation process, wherein the washing water amount is 180-_{Heavy soda ash}Removing salt and impurities on the surface of the crystal mush, and allowing the centrifugate to enter a mother liquid barrel; calcining, screening and cooling the solid obtained by the centrifugal machine to obtain a heavy soda ash product;

(4) treating 20-50% of heavy soda mother liquor in the mother liquor barrel by using evaporation equipment, evaporating to a point of common saturation of sodium carbonate and sodium chloride to separate out sodium carbonate monohydrate crystals, mixing the sodium carbonate monohydrate crystals and steam condensate for recycling to a hydrated crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate common saturated solution into a vacuum salt-making device of an integrated soda system;

(5) the method comprises the following steps of enabling heavy soda mother liquor with the volume of 50-80% in a mother liquor barrel to enter a clarifying device, adding sodium sulfide into the clarifying device according to a certain proportion, removing iron impurities in the mother liquor, enabling obtained clarified liquor to enter a hydration crystallizer in an original device to continue to prepare heavy soda, and enabling sediment at the bottom of the clarifying barrel to be sent to a salt mud treatment process of an alkali-associated system.

The ratio of sodium sulfide to heavy soda ash mother liquor in the clarifying device in the step (5) is 5-20mg/L_{Mother liquor of heavy soda ash}。

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

(1) the evaporation process is added in the invention, part of the heavy soda ash mother liquor is treated, the sodium chloride in the mother liquor is separated and discharged out of the heavy soda ash system, the sodium chloride is not increased accumulatively in the recycling process of the heavy soda ash mother liquor, the sodium chloride content in the heavy soda ash product can be reduced to be below 0.15%, and the product quality is improved.

(2) The invention adds a clarification process to reduce the accumulation of iron impurities in the heavy soda ash mother liquor, and can reduce the iron content in the heavy soda ash product to below 0.0018 percent and improve the whiteness of the product.

(3) The method can effectively remove sodium chloride and iron impurities in the heavy soda ash mother liquor, reduce impurities carried on the surface of the centrifuged crystal slurry, and reduce the washing water consumption of the centrifuge.

(4) The invention can reduce the discharge of the heavy soda mother liquor and reduce the environmental pollution and the resource waste.

Drawings

FIG. 1 is a schematic view of the process of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

The principle of the invention is as follows: the heavy soda ash mother liquor mainly contains sodium carbonate, sodium chloride and a small amount of ferrous impurities, and the sodium carbonate and the sodium chloride are separated by an evaporation crystallization method according to the solubility characteristics of the sodium carbonate and the sodium chloride. The heavy sodium carbonate solution is evaporated to the saturation point of sodium carbonate and sodium chloride, sodium carbonate is separated out from the solution, sodium chloride is not separated out, so that the separation of sodium carbonate and sodium chloride is realized, the content of sodium chloride in the heavy sodium carbonate mother liquor is reduced, the content of sodium chloride carried in the heavy sodium carbonate surface mother liquor separated out by hydration crystallization is reduced, and the washing water consumption and the content of sodium chloride in a heavy sodium carbonate product can be effectively reduced. Sodium sulfide is added into the solution and can react with ferrous ions in the solution to generate ferrous sulfide precipitate which is removed from the heavy soda ash mother liquor, so that the whiteness of the heavy soda ash product is improved.

Based on the above principle, the invention provides a production method of soda ash with heavy weight, as shown in fig. 1, which specifically comprises the following processes:

(1) according to the original process, adding light soda ash and sodium carbonate saturated solution (sodium dodecyl benzene sulfonate is added according to the weight percentage of 0.008-0.015) into a hydration crystallizer according to the proportion of 1:0.7-1:1 to carry out hydration crystallization reaction for 5-10 minutes.

(2) The solid-liquid ratio of crystal mush after hydration crystallization according to the prior art is 25-35%, the crystal mush is introduced into a thickener to adjust the solid-liquid ratio to be 35-45%, crystal mush at the bottom outlet of the thickener enters a centrifugal machine for solid-liquid separation, and supernatant of the thickener enters a mother liquor barrel.

(3) Washing is carried out by using washing water according to the prior process solid-liquid separation process, wherein the washing water amount is 180-_{Heavy soda ash}And removing salt and impurities on the surface of the crystal mush, and allowing the centrifugate to enter a mother liquid barrel. And calcining, screening and cooling the solid obtained by the centrifugal machine to obtain a heavy soda ash product.

The "original process" in the above steps (1) to (3) is the process in patent CN02148849.5 "a method for producing soda ash heavy".

(4) Treating the heavy soda mother liquor with the volume of 20-50% in the mother liquor barrel by using evaporation equipment, evaporating to a point of common saturation of sodium carbonate and sodium chloride to separate out sodium carbonate monohydrate crystals, mixing the sodium carbonate monohydrate crystals and the steam condensate for recycling to a hydration crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate common saturated solution into a vacuum salt-making device of an integrated soda system.

(5) And (3) allowing the heavy soda mother liquor with the volume of 50-80% in the mother liquor barrel to enter a clarifying device, adding sodium sulfide into the clarifying device according to a certain proportion, removing iron impurities in the mother liquor, and allowing the obtained clarified liquor to enter a hydration crystallizer in the original device to continuously prepare the heavy soda. Wherein the ratio of sodium sulfide to heavy soda ash mother liquor in the clarifying device is 5-20mg/L_{Mother liquor of heavy soda ash}Namely, 5-20mg of sodium sulfide is added into 1L of heavy soda ash mother liquor.

Example 1

Mixing the following components in percentage by weight: 0.7 of saturated solution of light soda ash and sodium carbonate was charged into a hydration crystallizer and hydration reaction was carried out at a temperature of 105 ℃ for 5 minutes. The solid-liquid volume ratio of the crystal mush after hydration is 35 percent, the crystal mush after hydration reaction is sent into a thickener to be thickened until the solid-liquid volume ratio is 45 percent, the crystal mush enters a centrifuge for dehydration, and is washed by using washing water in a head tank, and the washing water quantity is 220kg/t_{Heavy soda ash}Washing out salt and other impurities in the monohydrate caustic soda, dehydrating, drying in a heavy soda ash furnace, taking out of the furnace, performing particle size screening and cooling to obtain low-salt heavy soda ash, wherein supernatant of a thickener and washing water of a centrifugal machine enter a mother liquor barrel. Evaporating 20% of the heavy soda mother liquor in the mother liquor barrel by using an evaporation device, mixing sodium carbonate monohydrate crystals and steam condensate for recycling to a hydrated crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate co-saturated solution into a vacuum salt production device of an integrated alkali system. The mother liquor of heavy soda with 80% volume in the mother liquor barrel enters a clarifying device according to 5mg/L_{Mother liquor of heavy soda ash}And adding sodium sulfide, and returning supernatant to the water and recycling the crystallizer.

In this embodiment, the sodium chloride content of the prepared dense soda ash is 0.09% (the sodium chloride content is required to be lower than 0.2% in the index of the dense ash product), the iron content is 0.0018% (the iron content is required to be lower than 0.0035% in the index of the dense ash product), and the purity and whiteness of the product can be effectively improved.

Example 2

Mixing the following components in percentage by weight: 0.9 of saturated solution of light soda ash and sodium carbonate is added into a hydration crystallizer, and hydration reaction is carried out for 8 minutes at the temperature of 95 ℃. The solid-liquid volume ratio of the crystal mush after hydration is 29 percent, the crystal mush after hydration reaction is sent into a thickener to be thickened until the solid-liquid volume ratio is 42 percent, the crystal mush enters a centrifuge for dehydration, and is washed by using washing water in a head tank, and the washing water quantity is 200kg/t_{Heavy soda ash}Washing out salt and other impurities in the monohydrate caustic soda, dehydrating, drying in a heavy soda ash furnace, taking out of the furnace, performing particle size screening and cooling to obtain low-salt heavy soda ash, wherein supernatant of a thickener and washing water of a centrifugal machine enter a mother liquor barrel. Evaporating the heavy soda mother liquor with the volume of 30 percent in the mother liquor barrel by using evaporation equipment, mixing sodium carbonate monohydrate crystals and steam condensate for recycling to a hydrated crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate co-saturated solution into a vacuum salt production device of an integrated alkali system. The mother liquor of 70 percent of the volume of the heavy soda ash in the mother liquor barrel enters a clarifying device according to the proportion of 10mg/L_{Mother liquor of heavy soda ash}And adding sodium sulfide, and returning supernatant to the water and recycling the crystallizer.

In this embodiment, the sodium chloride content of the prepared soda ash is 0.12% (the sodium chloride content is required to be lower than 0.2% in the index of the heavy ash product), the iron content is 0.0015% (the iron content is required to be lower than 0.0035% in the index of the heavy ash product), and the purity and whiteness of the product can be effectively improved.

Example 3

Mixing the following components in percentage by weight: 1 and adding the saturated solution of the light soda ash and the sodium carbonate into a hydration crystallizer, and carrying out hydration reaction for 10 minutes at the temperature of 100 ℃. The solid-liquid volume ratio of the crystal mush after hydration is 25 percent, the crystal mush after hydration reaction is sent into a thickener to be thickened until the solid-liquid volume ratio is 35 percent, the crystal mush enters a centrifugal machine for dehydration, washing is carried out by using washing water in a head tank, and the washing water quantity is 180kg/t_{Heavy soda ash}Washing off the salt and other impurities in the monohydrate caustic sodaAnd (3) drying in a heavy soda ash furnace after dehydration, screening the particle size and cooling after discharging to prepare low-salt heavy soda ash, wherein supernatant of the thickener and washing water of a centrifugal machine enter a mother liquor barrel. Evaporating the heavy soda mother liquor with the volume of 30 percent in the mother liquor barrel by using evaporation equipment, mixing sodium carbonate monohydrate crystals and steam condensate for recycling to a hydrated crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate co-saturated solution into a vacuum salt production device of an integrated alkali system. The mother liquor of 70 percent of the volume of the heavy soda ash in the mother liquor barrel enters a clarifying device according to the proportion of 15mg/L_{Mother liquor of heavy soda ash}And adding sodium sulfide, and returning supernatant to the water and recycling the crystallizer.

In this embodiment, the sodium chloride content of the prepared soda ash is 0.15% (the sodium chloride content is required to be lower than 0.2% in the index of the heavy ash product), the iron content is 0.0011% (the iron content is required to be lower than 0.0035% in the index of the heavy ash product), and the purity and whiteness of the product can be effectively improved.

Example 4

Mixing the following components in percentage by weight: 0.8 of saturated solution of light soda ash and sodium carbonate is added into a hydration crystallizer, and hydration reaction is carried out for 7 minutes at the temperature of 103 ℃. The solid-liquid volume ratio of the crystal mush after hydration is 27 percent, the crystal mush after hydration reaction is sent into a thickener to be thickened until the solid-liquid volume ratio is 40 percent, the crystal mush enters a centrifugal machine for dehydration, washing is carried out by using washing water in a head tank, and the washing water quantity is 190kg/t_{Heavy soda ash}Washing out salt and other impurities in the monohydrate caustic soda, dehydrating, drying in a heavy soda ash furnace, taking out of the furnace, performing particle size screening and cooling to obtain low-salt heavy soda ash, wherein supernatant of a thickener and washing water of a centrifugal machine enter a mother liquor barrel. And (3) evaporating 50% of heavy soda mother liquor in the mother liquor barrel by using evaporation equipment, mixing sodium carbonate monohydrate crystals and steam condensate for recycling to a hydrated crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate co-saturated solution into a vacuum salt production device of an integrated alkali system. The mother liquor of 50 percent of the volume of the heavy soda ash in the mother liquor barrel enters a clarifying device according to the proportion of 20mg/L_{Mother liquor of heavy soda ash}And adding sodium sulfide, and returning supernatant to the water and recycling the crystallizer.

In this embodiment, the sodium chloride content of the prepared dense soda ash is 0.14% (the sodium chloride content is required to be lower than 0.2% in the index of the dense ash product), the iron content is 0.0009% (the iron content is required to be lower than 0.0035% in the index of the dense ash product), and the purity and whiteness of the product can be effectively improved.

Example 5

Mixing the following components in percentage by weight: 0.7 of saturated solution of light soda ash and sodium carbonate was charged into a hydration crystallizer and subjected to hydration reaction at a temperature of 98 ℃ for 9 minutes. The solid-liquid volume ratio of the crystal mush after hydration is 32 percent, the crystal mush after hydration reaction is sent into a thickener to be thickened until the solid-liquid volume ratio is 43 percent, the crystal mush enters a centrifuge for dehydration, and is washed by using washing water in a head tank, and the washing water quantity is 210kg/t_{Heavy soda ash}Washing out salt and other impurities in the monohydrate caustic soda, dehydrating, drying in a heavy soda ash furnace, taking out of the furnace, performing particle size screening and cooling to obtain low-salt heavy soda ash, wherein supernatant of a thickener and washing water of a centrifugal machine enter a mother liquor barrel. Evaporating 40% of heavy soda mother liquor in the mother liquor barrel by using evaporation equipment, mixing sodium carbonate monohydrate crystals and steam condensate for recycling to a hydrated crystallizer in the original device, and feeding the residual sodium chloride and sodium carbonate co-saturated solution into a vacuum salt making device of an integrated alkali system. The mother liquor of the soda ash with the volume of 60 percent in the mother liquor barrel enters a clarifying device according to the volume of 8mg/L_{Mother liquor of heavy soda ash}And adding sodium sulfide, and returning supernatant to the water and recycling the crystallizer.

In this embodiment, the sodium chloride content of the prepared heavy soda ash is 0.08% (the sodium chloride content is required to be lower than 0.2% in the index of the heavy ash product), the iron content is 0.0012% (the iron content is required to be lower than 0.0035% in the index of the heavy ash product), and the purity and whiteness of the product can be effectively improved.

While the present invention has been described in terms of its functions and operations with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise functions and operations described above, and that the above-described embodiments are illustrative rather than restrictive, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined by the appended claims.