KR102318052B1 - Manufacture method and equipment for sodium hydrogen carbonate and calcium carbonate - Google Patents

Abstract

According to an embodiment of the present invention, a sodium hydroxide (NaOH) solution is supplied with a carbon dioxide-containing gas to produce sodium hydroxide (NaHCO ₃ ) by a reaction of sodium hydroxide and carbon dioxide, a calcium ion-containing solution in the filtrate remaining after recovering the sodium hydroxide (NaOH) solution supplying to produce calcium carbonate (CaCO ₃ ) by the reaction of carbonate ions (CO ₃ ^2- ) and calcium ions, and re-supplying the filtrate remaining after recovering the calcium carbonate to the solution in which sodium hydroxide is dissolved It provides a sodium hydroxide and sodium carbonate manufacturing method and manufacturing equipment for supplying a sodium salt having a higher solubility than the sodium bicarbonate solution to the sodium hydroxide solution, and according to this, calcium carbonate, a high value-added material from discarded industrial by-products, and It is possible to produce sodium bicarbonate together, and there is an effect of preventing the problem of a decrease in the dissolution rate of calcium ions when a continuous process is implemented.

Description

Bicarbonate and calcium carbonate manufacturing method and manufacturing equipment

The present invention relates to a method and equipment for producing sodium bicarbonate and calcium carbonate from industrial by-products.

1 is a view schematically showing a conventional process for producing sodium bicarbonate and calcium carbonate from industrial by-products. _{The conventional sodium bicarbonate and calcium carbonate manufacturing process is an inorganic carbonate sodium bicarbonate (NaHCO 3} ) and calcium carbonate by constructing a fused process using carbon dioxide, calcium-containing industrial byproducts, and sodium hydroxide (NaOH) collected from power plants/steel mills, etc. (CaCO ₃ ) It relates to a technology for producing together.

Specifically, calcium ions are eluted from industrial by-products containing calcium using an eluent, and sodium hydroxide is supplied to the supernatant containing the eluted calcium ions to adjust the pH. Then, calcium carbonate is produced by supplying carbon dioxide. The filtrate remaining after recovering the calcium carbonate reacts with carbon dioxide in a sodium bicarbonate reactor to produce sodium bicarbonate. That is, sodium hydroxide input for pH control is recycled as a raw material for sodium bicarbonate, so that calcium carbonate and sodium bicarbonate are produced together.

^{On the other hand, in the sodium bicarbonate production process, sodium ions (Na +} ) and bicarbonate ions (HCO ₃ ^- ) are high in the filtrate remaining after recovering the precipitated sodium bicarbonate due to the high solubility of sodium bicarbonate, that is, the solubility of 96 g/L at 20 ° C. present in concentration. When the filtrate containing the bicarbonate ion in a high concentration is reused as an eluent, the bicarbonate ion is converted into _{carbonate ion (CO 3} ^{2- ) due to hydroxyl groups (OH − ) eluted from industrial by-products.} The converted carbonate ions react with calcium ions eluted from industrial by-products to form calcium carbonate, and this calcium carbonate covers the surface of industrial by-products such as slag, thereby making it difficult to elute additional calcium ions.

2 is a graph showing the amount of calcium ions eluted from industrial by-products according to the concentration of sodium bicarbonate dissolved in the eluent (2M aqueous ammonium chloride solution). According to FIG. 2, when sodium bicarbonate is not contained in the eluent or is contained in a trace amount, the concentration of eluted calcium ions exceeds 6,000 mg/L, but as the amount of sodium bicarbonate increases, the concentration of eluted calcium ions decreases. . When the content of sodium bicarbonate contained in the dissolution agent is 0.7 g/100 g-water, the dissolution rate is approximately 50% less than that in the case where sodium bicarbonate is not added. On the other hand, as the amount of sodium bicarbonate added increases, the amount of calcium ion elution rapidly decreases, and when sodium bicarbonate is fed up to equilibrium solubility, calcium ions are hardly eluted.

According to an embodiment of the present invention, it is an object to provide a method and equipment for producing calcium carbonate and sodium bicarbonate, which are high value-added substances, from discarded industrial by-products.

According to an embodiment of the present invention, supplying a carbon dioxide-containing gas to a sodium hydroxide (NaOH) solution to prepare a solution in which carbon dioxide is supplied, and producing sodium hydroxide (NaHCO ₃ ) by the reaction of sodium hydroxide and carbon dioxide, the step of Recovering sodium bicarbonate and supplying a calcium ion-containing solution to the remaining filtrate to produce calcium carbonate (CaCO _{3 ) through the reaction of carbonate ions (CO 3} ^2- ) and calcium ions, and the filtrate remaining after recovering the calcium carbonate It includes the step of re-supplying sodium hydroxide to the dissolved solution, the solution to which the carbon dioxide is supplied provides sodium bicarbonate and a method for producing calcium carbonate further comprising a sodium salt having a higher solubility than the sodium bicarbonate.

The sodium salt may be supplied before the carbon dioxide-containing gas is supplied to the sodium hydroxide solution.

The sodium salt may be supplied to the sodium hydroxide solution together with the carbon dioxide-containing gas, or may be supplied after the carbon dioxide-containing gas is supplied to the sodium hydroxide solution.

The sodium salt may be sodium nitrate (NaNO ₃ ), sodium chloride (NaCl), or a mixture thereof.

The calcium ion-containing solution may be prepared by eluting calcium ions from industrial by-products containing calcium using an eluent.

The eluent is an aqueous solution of ammonium chloride (NH ₄ Cl), hydrogen chloride (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), acetic acid (CH ₃ COOH), and ammonium nitrate (NH ₄ NO ₃ ). It can be selected from the group consisting of.

The industrial by-product may be at least one selected from the group consisting of iron slag, coal ash, bottom ash, fly ash, waste cement, waste concrete, and paper sludge.

The method may further include reusing the filtrate remaining after recovering the calcium carbonate as the eluent.

The carbon dioxide-containing gas is FINEX off gas (FOG), FINEX tail gas (FTG), blast furnace gas (BFG), converter gas, coal power plant flue gas, gas power plant flue gas, incinerator flue gas , it may be one or more selected from the group consisting of glass melting flue gas, thermal facility flue gas, petrochemical process flue gas, petrochemical process process gas, pre-combustion flue gas and gasifier flue gas.

According to another embodiment of the present invention, sodium hydroxide solution, carbon dioxide-containing gas, and sodium salt having a higher solubility than sodium bicarbonate are supplied to produce sodium bicarbonate through the reaction of sodium hydroxide and carbon dioxide, and the filtrate discharged from the sodium bicarbonate production unit and a calcium carbonate production unit to which a calcium ion-containing solution is supplied to produce calcium carbonate by a reaction between carbonate ions and calcium ions, wherein the filtrate discharged from the calcium carbonate production unit is re-supplied to the sodium bicarbonate production unit provides

It may further include an elution unit in which the calcium ion-containing solution is produced.

Industrial by-products and eluents containing calcium are supplied to the elution unit, and the calcium ions-containing solution can be produced by eluting calcium ions from industrial by-products by the eluent.

The filtrate discharged from the calcium carbonate production unit may be supplied to the elution unit.

The method and equipment for producing calcium carbonate and sodium bicarbonate according to an embodiment of the present invention can produce calcium carbonate and sodium bicarbonate, which are high value-added substances, together from discarded industrial by-products, and the dissolution rate of calcium ions decreases when a continuous process is implemented This is effective in preventing problems.

1 is a view schematically showing a conventional process for producing sodium bicarbonate and calcium carbonate from industrial by-products.
2 is a graph showing the amount of calcium ions eluted from industrial by-products according to the concentration of sodium bicarbonate dissolved in the eluent (2M ammonium chloride).
3 and 4 are views schematically showing sodium bicarbonate and calcium carbonate production facilities according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to various examples. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a method and equipment for producing sodium bicarbonate and calcium carbonate from industrial by-products, and specifically, sodium bicarbonate and It relates to a method and equipment for producing calcium carbonate.

According to an embodiment of the present invention, there is provided a method for producing sodium bicarbonate and calcium carbonate. This sodium hydroxide and calcium carbonate manufacturing method is a) supplying a gas containing carbon dioxide to a sodium hydroxide (NaOH) solution to produce sodium hydroxide (NaHCO ₃ ) through the reaction of sodium hydroxide and carbon dioxide, b) recovering the sodium hydroxide and adding the remaining filtrate supplying a solution containing calcium ions to produce calcium carbonate (CaCO _{3 ) by the reaction of carbonate ions (CO 3} ^2- ) and calcium ions, and c) recovering the calcium carbonate and using the remaining filtrate to dissolve the sodium hydroxide resupplying the solution.

First, a) When a carbon dioxide-containing gas is supplied to a sodium hydroxide solution, sodium hydroxide is produced by the reaction of the sodium hydroxide and carbon dioxide. Since the solubility of the sodium bicarbonate is 96 g/L at 20° C., the sodium bicarbonate is dissolved as much as the solubility in the filtrate remaining after recovering the precipitated sodium bicarbonate. Therefore, b) calcium carbonate is additionally produced by supplying calcium ions to the filtrate in which sodium bicarbonate is dissolved. That is, by performing steps a) and b), sodium bicarbonate and calcium carbonate, which are high value-added substances, can be prepared together. On the other hand, since the filtrate remaining after recovering the calcium carbonate contains sodium ions and bicarbonate ions, the filtrate is supplied to a solution in which the sodium hydroxide is dissolved and reused in sodium bicarbonate production.

Hereinafter, it will be described in detail step by step.

First, a) When a carbon dioxide-containing gas is supplied to a sodium hydroxide solution, sodium hydroxide is produced by the reaction of the sodium hydroxide and carbon dioxide. The reaction formula of this sodium bicarbonate production reaction is as shown in Equation 1 below.

Formula 1: NaOH + CO ₂ → NaHCO ₃

Since the solubility of the sodium bicarbonate is 96 g/L at 20° C., the sodium bicarbonate is dissolved as much as the solubility in the filtrate remaining after recovering the precipitated sodium bicarbonate. That is, sodium ions (Na ⁺ ), bicarbonate ions (HCO ₃ ⁻ ), and carbonate ions (CO ₃ ^2- ) are dissolved in the filtrate.

*46

On the other hand, the carbon dioxide-containing gas is a by-product generated in an industrial process such as an iron making process, for example, FINEX off gas (FOG, FINEX off gas), FINEX tail gas (FTG, FINEX tail gas), blast furnace gas (BFG, Blast furnace gas), converter gas, coal power plant flue gas, gas power plant flue gas, incinerator flue gas, glass melting flue gas, thermal facility flue gas, petrochemical process flue gas, petrochemical process process gas, pre-combustion flue gas and gasifier flue gas There may be more than one.

According to an embodiment of the present invention, a sodium salt having a higher solubility than the sodium hydroxide is further supplied to the sodium hydroxide solution. The sodium salt serves to improve the precipitation amount of sodium bicarbonate by a common ion effect.

Specifically, sodium bicarbonate having a solubility of 96 g/L at 20° C. is in equilibrium in a state in which sodium ions and bicarbonate ions are formed as shown in Equation 2 below.

Formula 2: NaHCO ₃ ↔Na ⁺ + HCO ₃ ^-

When a sodium salt, for example, sodium chloride is added to such an equilibrium system, the sodium chloride is divided into sodium ions and chloride ions as shown in Equation 3 below.

Formula 3: NaCl → Na ⁺ + Cl ^-

Since the sodium ion entering the equilibrium system of Equation 2 is the same ion as the sodium ion participating in the original equilibrium, it acts as a factor to increase the concentration of sodium ions in the equilibrium system. Thus, according to Le Chatelier's principle, the equilibrium is shifted to the left in Equation 2 to decrease the concentration of sodium ions, reaching a new equilibrium. When the equilibrium is shifted in this way, the concentration of bicarbonate ions in the sodium bicarbonate equilibrium system decreases, resulting in the precipitation of sodium bicarbonate. That is, when sodium salt is supplied during the sodium bicarbonate production reaction, sodium chloride is dissolved, resulting in an effect of improving the precipitated amount of sodium bicarbonate by the common ion effect of sodium ions.

The sodium salt may be supplied to the sodium hydroxide solution before the carbon dioxide-containing gas is supplied to the sodium hydroxide solution. When the sodium salt is supplied to the sodium hydroxide solution before supplying the carbon dioxide-containing gas, the solubility of carbon dioxide is increased as the precipitated amount of sodium bicarbonate is improved, so that the content of carbon dioxide discharged into the air without being dissolved in the solution can be reduced. There is this.

Meanwhile, the sodium salt may be supplied to the sodium hydroxide solution together with the carbon dioxide-containing gas, or after the carbon dioxide-containing gas is supplied to the sodium hydroxide solution. When the sodium salt is supplied to the sodium hydroxide solution together with the carbon dioxide-containing gas, or after supplying the carbon dioxide-containing gas, there is an advantage in that sodium carbonate having a desired content can be obtained by controlling the amount of precipitated sodium bicarbonate.

The sodium salt is not particularly limited as long as it has higher solubility than sodium bicarbonate and contains sodium ions, but _{is preferably sodium nitrate (NaNO 3} ), sodium chloride (NaCl), or a mixture thereof.

^{Meanwhile, sodium ions (Na +} ), bicarbonate ions (HCO ₃ ⁻ ), carbonate ions (CO ₃ ^2- ), and the like are dissolved in the filtrate remaining after the precipitated sodium bicarbonate is recovered. Therefore, b) when a calcium ion-containing solution is supplied to the filtrate, calcium _{carbonate (CaCO 3} ) is produced by the reaction of carbonate _{ions (CO 3} ^{2- ) and calcium ions.} The reaction formula of this calcium carbonate production reaction is as shown in Equation 4 below.

Equation 4: CO ₃ ^2- + Ca ²⁺ → CaCO ₃

Therefore, calcium carbonate can be additionally produced by supplying calcium ions to the filtrate remaining after recovering sodium bicarbonate. That is, according to the manufacturing method according to an embodiment of the present invention, sodium hydroxide and calcium carbonate, which are high value-added substances, can be manufactured together using only a calcium ion-containing material, sodium hydroxide, and a carbon dioxide-containing gas.

The calcium ion-containing solution supplied to the filtrate may be prepared by eluting calcium ions from industrial by-products containing calcium. The industrial by-product is not particularly limited as long as it contains calcium, but for example, it may be one or more selected from the group consisting of iron slag, coal ash, bottom ash, fly ash, waste cement, waste concrete, and paper sludge. .

Calcium ions can be eluted from the industrial by-products using an eluent, and the type of such eluent is not particularly limited, but, for example, ammonium chloride (NH ₄ Cl), hydrogen chloride (HCl), nitric acid (HNO ₃ ) , sulfuric acid (H ₂ SO ₄ ), acetic acid (CH ₃ COOH), and ammonium nitrate (NH ₄ NO ₃ ) It is preferable to use at least one selected from the group consisting of an aqueous solution.

The concentration of calcium ions contained in the calcium ion-containing solution is preferably higher than the combined concentration of bicarbonate ions and carbonate ions contained in the filtrate. The expression remaining filtrate after the recovery of the calcium carbonate produced in the reaction of 4 may be re-dissolution agent, wherein, If the filtrate contains a bicarbonate ion hydroxyl groups (OH ^-) eluted in the industrial by-product wherein due to bicarbonate ion This is converted into carbonate ions (CO ₃ ^{2- ).} Carbonate ions and converted carbonate ions contained in the filtrate can react with calcium ions eluted from industrial by-products to form calcium carbonate, and these calcium carbonates cover the surface of industrial by-products such as slag to prevent the elution of additional calcium ions. problems may arise.

However, when the concentration of calcium ions included in the calcium ion-containing solution is controlled to be higher than the combined concentration of bicarbonate ions and carbonate ions included in the filtrate, both the bicarbonate ions and carbonate ions can be converted into calcium carbonate. Therefore, since the filtrate does not contain bicarbonate ions and carbonate ions, it is possible to prevent the problem of preventing the elution of calcium ions from industrial by-products when the filtrate remaining after recovery of calcium carbonate is reused as an eluent.

Meanwhile, c) the filtrate remaining after recovering the calcium carbonate contains sodium ions and bicarbonate ions, and the filtrate is supplied to a solution in which the sodium hydroxide is dissolved and reused in sodium bicarbonate production. In addition, as described above, the filtrate remaining after recovering the calcium carbonate may be reused as the eluent.

*83 The present invention provides facilities for producing sodium bicarbonate and calcium carbonate. 3 and 4 are views schematically showing facilities for producing sodium bicarbonate and calcium carbonate according to an embodiment of the present invention.

In the manufacturing facility according to an embodiment of the present invention, sodium hydroxide solution, carbon dioxide-containing gas, and sodium salt having a higher solubility than sodium bicarbonate are supplied to produce sodium bicarbonate by the reaction of sodium hydroxide and carbon dioxide, and in the sodium bicarbonate production unit The discharged filtrate and calcium ion-containing solution are supplied to include a calcium carbonate production unit in which calcium carbonate is produced by the reaction of carbonate ions and calcium ions.

The sodium hydroxide production unit is produced by the reaction of the supplied sodium hydroxide solution and the carbon dioxide-containing gas. The carbon dioxide-containing gas is generated in an industrial process such as the steel industry and is not particularly limited as long as it contains carbon dioxide, but for example, FINEX off gas (FOG, FINEX off gas), FINEX tail gas (FTG, FINEX tail gas), Blast furnace gas (BFG), converter gas, coal power plant flue gas, gas power plant flue gas, incinerator flue gas, glass melting flue gas, thermal facility flue gas, petrochemical process flue gas, petrochemical process process gas, pre-combustion flue gas and gasifier flue gas It may be one or more selected from the group consisting of.

On the other hand, sodium salt having a higher solubility than sodium bicarbonate is supplied to the sodium bicarbonate production unit, which serves to improve the precipitated amount of sodium bicarbonate as described above. On the other hand, the sodium salt is not particularly limited as long as it has higher solubility than sodium bicarbonate and contains sodium ions, for example, sodium nitrate (NaNO ₃ ), sodium chloride (NaCl), or a mixture thereof.

Sodium bicarbonate is precipitated in the sodium bicarbonate production unit, and the filtrate remaining after separating the precipitated sodium bicarbonate is supplied to the calcium carbonate production unit. The filtrate and the calcium ion-containing solution are supplied to the calcium carbonate production unit, and calcium carbonate is produced by the reaction of the carbonate ions and the calcium ions contained in the filtrate. Therefore, the manufacturing facility according to an embodiment of the present invention can produce calcium carbonate together with sodium bicarbonate.

The manufacturing facility according to an embodiment of the present invention may further include an elution unit in which the calcium ion-containing solution is produced. Industrial by-products and eluents containing calcium are supplied to the elution part, and the eluents elute calcium ions from industrial by-products to prepare the calcium ion-containing solution.

The industrial by-product is not particularly limited as long as it contains calcium, but may be one or more selected from the group consisting of coal ash, bottom ash, fly ash, waste cement, waste concrete, and paper sludge. On the other hand, the eluent may use an acid, a base, etc., for example, ammonium chloride (NH ₄ Cl), hydrogen chloride (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), acetic acid (CH _{3 )} COOH), and at least one selected from the group consisting of an aqueous solution of _{ammonium nitrate (NH 4} NO _{3 ) is preferable.}

Since the filtrate discharged from the calcium carbonate production unit contains an eluent, sodium ions, bicarbonate ions, and the like, it may be re-supplied to the sodium bicarbonate production unit or supplied to the elution unit to reuse as an eluent. Alternatively, a portion of the filtrate may be re-supplied to the sodium bicarbonate production unit, and the remaining portion may be supplied to the elution unit to be reused as an eluent.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible within the scope without departing from the technical spirit of the present invention described in the claims. It will be apparent to those of ordinary skill in the art.

Claims (4)

a sodium hydroxide solution, a carbon dioxide-containing gas, and a sodium salt having a higher solubility than sodium bicarbonate are supplied to produce sodium bicarbonate through the reaction of sodium hydroxide and carbon dioxide; and
and a calcium carbonate production unit in which the filtrate and calcium ion-containing solution discharged from the sodium bicarbonate production unit are supplied to produce calcium carbonate by the reaction of carbonate ions and calcium ions,
A sodium bicarbonate and calcium carbonate manufacturing facility in which the filtrate discharged from the calcium carbonate production unit is re-supplied to the sodium bicarbonate production unit.
The sodium bicarbonate and calcium carbonate production facility according to claim 1, further comprising an elution unit in which the calcium ion-containing solution is produced.
3. The method of claim 2,
Industrial by-products and eluents containing calcium are supplied to the elution unit, and the calcium ions are eluted from the industrial by-products to produce the calcium ion-containing solution, sodium bicarbonate and calcium carbonate manufacturing equipment.
The sodium carbonate and calcium carbonate manufacturing facility according to claim 2, wherein the filtrate discharged from the calcium carbonate production unit is supplied to the elution unit.

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