JP2022089172A - Method for treating substance containing alkaline-earth metals and valuables, and method for recovering valuables from substance containing alkaline-earth metals and valuables - Google Patents

Abstract

To provide a method for treating a substance containing alkaline-earth metals and valuables that makes it possible to increase, in inexpensive manner, the weight ratio of valuable components in residues, which occur as byproducts when extracting alkaline-earth metals from a substance containing alkaline-earth metals and valuables.SOLUTION: The inventive method includes the steps of: bringing a substance containing alkaline-earth metals and valuables into contact with an aqueous solution containing a weak base and a salt of strong acid to generate an alkaline-earth metal extract and a residue, which are separated from each other; and bringing the residue into contact with an aqueous solution containing a salt of strong acid, to cause nonferrous components to leach out in the aqueous solution, increasing the ratio of the valuables in the residue.SELECTED DRAWING: Figure 1

Description

The present invention is a method for treating a substance containing a valuable substance such as an alkaline earth metal and iron, particularly a valuable substance contained in the residue after separating the substance into an alkaline earth metal extract and a residue. A method for treating substances containing alkaline earth metals and valuables, which makes it possible to increase the component weight ratio and further immobilize CO ₂ (carbon dioxide) as a carbonate, and alkaline earth metals and The present invention relates to a method of recovering valuable resources from a substance containing valuable resources.

Since the Industrial Revolution, the concentration of CO ₂ in the atmosphere has continued to increase, and in recent years, the phenomenon of global warming due to the increase in CO ₂ concentration has become a problem. The main factors for the increase in CO ₂ are fossil fuel consumption and deforestation. As part of measures against the rise in the atmospheric concentration of CO ₂ , research on the separation, recovery, and immobilization of carbon dioxide is being actively conducted. As separation techniques, research on absorption method, adsorption method, and membrane separation method is being actively conducted. As a technique for immobilizing separated CO ₂ , research is being conducted based on a chemical immobilization method, a biological immobilization method, and an isolated storage method. In particular, the chemical immobilization method is a method in which the alkaline earth metal leached into the liquid is brought into contact with CO ₂ and carbonated to fix it, and the carbonate produced is stable and harmless, so it is promising. Method.

In the above method of immobilizing CO ₂ as a carbonate, alkaline earth metal elements that contribute to the reaction are often contained mainly in natural minerals, waste materials, or by-products discharged in the manufacturing process.
For example, Patent Document 1 presents a CO ₂ immobilization method for treating CO ₂ using a Ca component contained in mortar waste powder as an inorganic material contained in industrial waste.
Patent Document 2 states that industrial waste containing CaO and / or MgO is brought into contact with water to elute alkaline earth metals, and then the solution is brought into contact with CO ₂ to precipitate CaCO ₃ and / or MgCO ₃ . So, a method of immobilizing CO ₂ is presented.
In Patent Document 3, an alkaline earth metal-containing substance is brought into contact with an aqueous solution obtained from a salt of a weak base and a strong acid to transfer the alkaline earth metal into the aqueous solution, and the alkaline earth metal is brought into contact with a gas containing carbon dioxide to form a carbonate. A method of generation is presented.

Further, in Patent Document 4, regarding calcification of calcium contained in industrial waste, a first fraction having a large amount of calcium and a second fraction having a large amount of heavy matter are formed, and the first fraction is CO ₂ A method has been proposed in which the weight ratio of iron contained in the second fraction is increased by carbonating with the contained gas and fixing to the carbonate.

Japanese Unexamined Patent Publication No. 2000-140651 Japanese Unexamined Patent Publication No. 7-265688 Japanese Unexamined Patent Publication No. 2005-97072 Special Table 2015-506413 Gazette

Removal of alkaline earth elements from alkaline earth-containing substances according to the methods of Patent Documents 1, 2 and 3 results in the formation of residues. Patent Documents 1, 2 and 3 do not mention a method for treating the residue, but when the residue is treated as waste, an environmental load and a treatment cost are incurred. This is not practical in terms of process, and it is required to establish a method for treating the residue.

In this regard, in the method described in Patent Document 4, after the calcium component contained in the industrial waste is leached with an ammonium nitrate solvent, the weight ratio of iron contained in the produced residue is increased to remove the residual iron contained in the residue. It is possible to use it effectively. However, there is a trade-off between the concentration of residual iron contained in the residue and the concentration of Ca in the leachate, and when trying to increase the concentration of residual iron, components other than Ca are relative to the liquid side. In the ammonium nitrate solvent to be circulated, impurities that do not contribute to the reaction are accumulated, the solvent exchange cycle is shortened, and the solvent exchange cost is increased. Furthermore, the above residue may contain valuable resources such as magnesium and aluminum in addition to iron, and recovery of these may be desired.

The present invention solves the above-mentioned problems, and the weight of the valuable component in the residue produced as a by-product when the alkaline earth metal is extracted from a substance containing a valuable resource such as an alkaline earth metal and iron. Valuables such as alkaline earth metals and iron that realize increasing the ratio and immobilizing the alkaline earth metal extract to carbonate by contacting it with CO ₂ by an inexpensive method. It is an object of the present invention to provide a method for treating a substance containing a substance. Furthermore, it is an object of the present invention to provide a method for recovering valuable resources from substances containing alkaline earth metals and valuable resources using the above-mentioned treatment methods.

In order to solve the above problems, the present invention brings an alkaline earth metal and a substance containing a valuable substance into contact with an aqueous solution containing a salt of a weak base and a strong acid, and preferentially puts the alkaline earth metal into the aqueous solution. It is possible to increase the weight ratio of the valuable component in the residue by contacting the leached and generated residue with an aqueous solution containing a strong acid salt to leached components other than the valuable component. be. Further, based on the process of the present invention, it is possible to carry out the concentration of calcium in the liquid used for carbonate immobilization and the recovery of valuable resources from the solid residue by independent methods.

That is, the gist structure of the present invention is as follows.
(1) A substance containing an alkaline earth metal and a valuable substance is brought into contact with an aqueous solution containing a salt of a weak base and a strong acid to form an alkaline earth metal extract and a residue, and the alkaline earth metal extract and the residue are produced. And the process of separating into
Alkaline earth metals and valuables, comprising contacting the residue with an aqueous solution containing a salt of a strong acid to leach components other than valuables into the aqueous solution to increase the proportion of iron in the residue. A method for treating a substance containing.
Here, the above-mentioned "aqueous solution containing a salt of a weak base and a strong acid" means an aqueous solution containing a weak base and a strong acid as a solute. Similarly, the above-mentioned "aqueous solution containing a salt of a strong acid" means an aqueous solution containing a strong acid as a solute. As the salt used in the present invention, any salt formed from a salt of a weak base and a salt of a strong acid can be used. Examples of the weak base include organic bases such as hydrazine derivatives such as ammonia, methylamine, alinine, pyridine, hydrazine and methylhydrazine, and inorganic compound bases such as magnesium hydroxide, iron hydroxide, copper hydroxide and zinc hydroxide. .. Examples of the salt of the strong acid include hydrochloric acid, sulfuric acid, nitric acid, chromium acid, permanganic acid, hydroiodic acid, hydrobromic acid and the like.

(2) A substance containing an alkaline earth metal and a valuable substance is brought into contact with an aqueous solution containing a salt of a weak base and a strong acid to form an alkaline earth metal extract and a residue, and the alkaline earth metal extract and the residue are produced. And the process of separating into
A step of contacting a gas containing carbon dioxide with the alkaline earth metal extract to generate a carbonate,
Alkaline earth metals and valuables, comprising contacting the residue with an aqueous solution containing a salt of a strong acid to leach components other than valuables into the aqueous solution to increase the proportion of valuables in the residue. A method for treating substances containing substances.

(3) The method for treating a substance containing an alkaline earth metal and a valuable resource according to (2) above, wherein the gas containing carbon dioxide is an exhaust gas discharged from a manufacturing facility.

(4) The method for treating a substance containing an alkaline earth metal and a valuable resource according to (2) above, wherein the gas containing carbon dioxide gas contains NOx or SOx.

(5) The substance containing the alkaline earth metal and valuable resources is any one of (1) to (4) above, which is at least one of natural minerals, waste materials, and by-products discharged in the manufacturing process. The method for treating a substance containing an alkaline earth metal and a valuable resource according to the above.
Here, the manufacturing process includes, for example, an iron-making process or a steel-making process in the iron-making field.

(6) The substance containing the alkaline earth metal and valuables is at least one of pyroxene, amphibole, ankerite, pomegranate stone, green brick and fluffy stone (1) to (4). A method for treating a substance containing an alkaline earth metal and a valuable resource according to any one of the above.

(7) The alkaline earth metal and valuable material according to any one of (1) to (4) above, wherein the substance containing the alkaline earth metal and valuable resources is steel slag discharged in the steelmaking process or the steelmaking process. A method for treating substances containing substances.

(8) The alkali according to any one of (1) to (7) above, wherein the valuable resource is at least one of iron, magnesium, silicon, aluminum, manganese, phosphorus, cadmium, lead, boron and arsenic. A method for treating substances containing earth metals and valuable resources.

(9) A substance containing an alkaline earth metal and a valuable substance is brought into contact with an aqueous solution containing a salt of a weak base and a strong acid to form an alkaline earth metal extract and a residue, and the alkaline earth metal extract and the residue are produced. And the process of separating into
A step of bringing the residue into contact with an aqueous solution containing a salt of a strong acid, leaching components other than valuables into the aqueous solution, and recovering the residue from which the components other than the valuables have been removed as valuables.
A method for recovering valuable resources from substances containing alkaline earth metals and valuable resources.

(10) The alkali according to (9) above, wherein the substance containing the alkaline earth metal and valuables is at least one of pyroxene, amphibole, ankerite, pomegranate stone, green brick and fluffy stone. A method for recovering valuable resources from substances containing earth metals and iron.

(11) The alkaline earth metal according to (9) or (10) above, wherein the valuable material is at least one of iron, magnesium, silicon, aluminum, manganese, phosphorus, cadmium, lead, boron and arsenic. And a method of recovering valuables from substances containing valuables.

According to the present invention, a substance containing valuable resources such as alkaline earth metal and iron is brought into contact with an aqueous solution containing a salt of a weak base and a strong acid, and the alkaline earth metal is preferentially leached into the aqueous solution. The ratio of the valuable substance in the residue can be increased by an inexpensive method in which the produced residue is brought into contact with an aqueous solution containing a strong acid salt to leach out components other than the valuable component. Further, in the present invention, by adjusting the concentration of the aqueous solution containing the salt of the strong acid, the ratio of the valuable resource can be arbitrarily adjusted in the range exceeding the concentration of the residue before the treatment. Therefore, valuable resources can be efficiently recovered from substances containing alkaline earth metals and valuable resources.

Further, in the present invention, a step of contacting a gas containing carbon dioxide gas with a gas containing carbon dioxide gas to generate a carbonate is added to the alkaline earth metal extract obtained by preferentially leaching the alkaline earth metal into the aqueous solution. , CO ₂ (carbon dioxide) can be immobilized as a carbonate by an inexpensive method.
Therefore, it is possible to adjust the calcium concentration in the liquid used for carbonate immobilization and the ratio of the valuable resource contained in the residue by an independent method.
Furthermore, even for substances that are normally difficult to recycle, many elements can be separated and recycled, which can bring about beneficial effects on the environment.

It is a schematic flow chart from the extraction of the alkaline earth metal of this invention to the recovery of a valuable (iron) recovered material, and the immobilization of carbonate. It is a schematic flow chart from the extraction of the alkaline earth metal of this invention to the recovery of a valuable (iron) recovered material, and the immobilization of carbonate. It is a figure which shows the test apparatus of the calcium extraction test used in the example of this invention. It is a figure which shows the relationship between the iron concentration and time at the time of recovering an iron component from a residue. It is a figure which shows the test apparatus of the calcium carbonate precipitation test used in the example of this invention. It is a figure which shows the SEM image of the precipitate formed at the time of carbonate fixation. It is a figure which shows the X-ray-diffraction peak of the precipitate formed at the time of carbonate immobilization.

Hereinafter, a method for treating a substance containing an alkaline earth metal and a valuable resource to which the present invention is applied will be described with reference to the drawings, with the case where the valuable resource is iron as a typical example. The drawings used in the following description are for explaining the configuration of the embodiment of the present invention, and are not limited to the illustrated embodiment.

[First Embodiment]
In the first embodiment according to the present invention, as shown in the process flow in FIG. 1, a substance containing an alkaline earth metal and an iron component is used as a raw material (hereinafter, also simply referred to as a raw material), and the raw material is acid-leached and solid-liquid separated. By doing so, a step of recovering the alkaline earth metal extract from which the alkaline earth metal is preferentially leached and the residue 1 (step A), and a valuable step including iron from the residue 1 generated in this step A. It consists of a step of collecting an object (step B).

As the substance containing alkaline earth metal and iron, for example, any one of pyroxene, amphibole, ankerite, slag stone, green brick and slag stone, or steel discharged in the steelmaking process or the steelmaking process. Slag etc. can be mentioned.
Hereinafter, step A and step B will be described in detail.

[Step A]
The extract used for acid leaching in step A is an aqueous solution containing a salt of a weak base and a strong acid. As the salt used in the present invention, any salt formed from a weak base and a strong acid can be used. For example, ammonium chloride, copper chloride, magnesium chloride, magnesium nitrate, zinc nitrate, iron nitrate, aluminum chloride, hydrazine hydrochloride, hydrazine sulfate and the like can be mentioned.

It is preferable to adjust the concentration of the extract (an aqueous solution containing a salt of a weak base and a strong acid) within the range of 1.0 to 10 N before use. This is because if the concentration of the extract is less than 1.0 N, the elution amount of slag-containing calcium may be low, while if it exceeds 10 N, the elution rate of slag-containing calcium is saturated and the cost is high due to the excessive amount of drug input. There is a risk of becoming. The mixing time of the raw material and the extract (an aqueous solution containing a salt of a weak base and a strong acid) is arbitrarily determined according to the concentration of the extract.

The mixing ratio of the salt, water and the alkaline earth metal-containing substance is preferably 1:15: 1 in mass ratio. This is because if the ratio of salt and water is higher than the above ratio, it becomes economically disadvantageous due to the increase in the amount of chemicals used, and if the mixing ratio of the alkaline earth metal-containing substance is increased, the calcium leached out is saturated in the liquid. This is because the calcium leaching rate has reached a plateau.

The temperature of the above-mentioned aqueous salt solution (extract) is usually about room temperature to 100 ° C, preferably about 60 to 80 ° C. In such a relatively low temperature range, the temperature of the extract can be controlled by utilizing, for example, inexpensive low-grade waste heat in a steel mill. Since the temperature of carbon dioxide-containing exhaust gas discharged from a factory (for example, a steel mill) used in step C described later is usually about 100 to 200 ° C., the extract is heated by using such exhaust gas. Can be done.

In this step A, in the next step B, the residue 1 for obtaining the iron recovered product is recovered and the alkaline earth metal is extracted. The particle size of the raw material applied to the step A does not need to be particularly limited, but is usually 6 mm or less, more preferably 500 μm or less.
For example, a mixture of DEA (diethanolamine) and HCl is used as the salt in the extract used in this step A, and steelmaking slag (2CaO · SiO ₂ or 3CaO as the main component) is used as a substance containing alkaline earth metal and iron. -When SiO ₂ ) is used, it is considered that the reaction represented by the following equation (i) is occurring.
2CaO ・ SiO ₂ + 4 (DEA + HCl) → 4 (DEA) + SiO ₂ ↓ + 2CaCl ₂ + 2H ₂ O… (i)

The proportion of iron contained in the residue 2 recovered in the next step B is proportional to the concentration of the alkaline earth contained in the alkaline earth metal extract used in the later step C in the solution. However, by adjusting the acid leaching conditions in this step A, it is possible to adjust the iron ratio and alkaline earth concentration according to the purpose.

[Step B]
In step B, the residual organic matter is recovered from the solid residue 1 after extracting the alkaline earth metal in step A. For example, in the case of steel slag, the solid residue 1 may contain valuable resources such as magnesium, silicon, aluminum, manganese, phosphorus, chromium, cadmium, lead, boron and arsenic, in addition to iron. .. For example, iron can be precipitated and recovered as iron hydroxide by dissolving it with an acid and then performing solid-liquid separation and adjusting the pH and redox potential.

Compounds such as magnesium, aluminum, manganese, chromium, cadmium, and lead can be recovered by a similar method. For example, manganese can be recovered even at a low pH by increasing the redox potential with ozone, hypochlorous acid, or the like. Chromium can be efficiently recovered by reducing it to trivalent using a reducing agent. Further, phosphorus can be recovered as iron phosphate by adjusting the pH if iron coexists. Similarly, arsenic can be recovered by iron. Boron can be recovered by coagulation precipitation using aluminum and calcium, an adsorption resin, or the like.

When multiple elements are recovered at the same time and the purity of the recovered material (valuable resource) becomes low, the recovered product (valuable resource) is separated from the solvent by a general method such as solvent extraction in a dissolved state, and then the recovery operation is performed. It is possible to increase the purity and recover by performing the above.

On the contrary, it is also possible to recover the valuable resources as a solid by dissolving only unnecessary components and leaving the valuable resources to be recovered in the solid residue 2. For example, in the case of iron, by changing the concentration of the acid to act on and selectively dissolving only the components other than iron and leaving the iron component on the solid side, the iron content in the solid is increased and the recovered product is recovered. The value can be improved.

The method of leaving the valuable resources to be recovered in the solid residue 2 will be described in detail with reference to FIG. Note that FIG. 2 shows the details of step B, and step A and step C described later are the same as those in FIG.
That is, it is a method of subjecting the residue 1 recovered in the above step A to acid leaching to recover the residue 2 as an iron recovered product and the washing liquid. Here, the extract used for acid leaching is an aqueous solution containing a salt of a strong acid. As the salt used in the present invention, any salt formed from a strong acid can be used. For example, hydrochloric acid, sulfuric acid, nitric acid, chromium acid, permanganic acid, hydrogen iodide acid, hydrobromic acid and the like can be mentioned.

It is preferable to adjust the concentration of the extract in the range of 1.0-10N before use. This is because if the concentration of the extract is less than 1.0 N, the elution amount of slag-containing calcium may be low, while if it exceeds 10 N, the elution rate of slag-containing calcium is saturated and the cost is high due to the excessive amount of drug input. There is a risk of becoming. Further, the mixing time between the raw material and the extract is arbitrarily determined according to the concentration of the extract.

In this way, by adjusting the concentration of the aqueous solution obtained from the salt of the strong acid that comes into contact with the iron contained in the residue in the range of 1.0 to 10 N, the iron content is adjusted in the region exceeding the concentration of the residue as originally produced. It can be adjusted arbitrarily. That is, the ratio of iron contained in the residue can be adjusted to a desired range. Therefore, for example, in a steel mill, residual iron that has normally been treated as slag can be used as a new iron source for refining, which is an environmentally and economically useful effect.

In this step B, the residue 1 recovered in the above step A is subjected to acid leaching, and the residue 2 as an iron recovered product and the washing liquid can be recovered. It is important that the proportion of iron contained in the residue 2 is relatively increased with respect to the proportion of iron contained in the residue 1. Therefore, it is necessary to preferentially leach the alkaline earth metal component, which is a component other than the iron component, by contacting the residue 1 with an aqueous solution (extract) containing a salt of a strong acid. The extract used in this step can be recirculated in the acid leaching of the residue 1 after being solid-liquid separated by acid leaching to obtain the residue 2.

The residue 2 is preferably dehydrated and heat-dried to remove the water adhering to the residue, and the iron to be recovered is preferably in the form of dry powder. That is, by recovering iron as a dry powder, post-treatment with a high degree of freedom, such as using the recovered material for sintering and recycling, becomes possible.

Here, when, for example, steelmaking slag is used as the raw material (substance containing alkaline earth metal and iron) in step A, HCl and HF are used as strong acids to dissolve CaO and SiO ₂ remaining in the residue 1. It is preferable to contact and dissolve the mixed solution of (hydrogen fluoride). At that time, SiO ₂ is generated, but since this SiO ₂ is insoluble in the HCl solution, it is dissolved by the reaction as shown in the following formula (ii).
SiO ₂ + 6HF → H ₂ SiF ₆ + 2H ₂ O… (ii)

[Second Embodiment]
The second embodiment according to the present invention includes the above-mentioned steps A and B as shown in FIG. 1 or FIG. 2, and further carbonates the alkaline earth metal extract separated from the raw material in the step A. It has a step (step C) of recovering the carbonate and the washing liquid by solid-liquid separation after precipitating the carbonate by introducing a gas and bringing them into contact with each other. This step C will be described below.

[Process C]
In this step C, carbonate is brought into contact with the alkaline earth metal extract extracted in step A to precipitate and precipitate the carbonate, and then the carbonate and the washing liquid are separated into solid and liquid to form a carbonate. To collect. The washing liquid generated in this step C can be recycled for acid leaching in step A after solid-liquid separation. The gas containing carbon dioxide gas applied in the present invention is not particularly limited as long as it contains carbon dioxide gas, and includes carbon dioxide gas-containing exhaust gas discharged from various manufacturing facilities.

For example, a mixture of DEA (diethanolamine) and HCl is used as a salt in the extract used in step A, and steelmaking slag (2CaO · SiO ₂ or 3CaO · as a main component) as a substance containing an alkaline earth metal and iron. When SiO ₂ ) is used, it is considered that the reaction as shown in the following formula (iii) occurs in this step C in which carbon dioxide gas is brought into contact with the alkaline earth metal extract extracted in this step A. In this way, CaCO ₃ can be generated and carbon dioxide gas can be immobilized. DEA + HCl is recycled as an extract of alkaline earth metal in step A and used repeatedly.
4 (DEA) + 2H _2O + 2CaCl ₂ + 2CO ₂ → 4 (DEA + HCl) + 2CaCO ₃ … (iii)

CaCO ₃ (calcium carbonate) and SiO ₂ produced by immobilizing carbon dioxide gas in this step C are harmless and stable substances, and are expected to be used in various ways. Specific examples of the use of CaCO ₃ include auxiliary raw materials for iron making, raw materials for cement, refractory raw materials, fertilizers, and the like. On the other hand, examples of the use of SiO ₂ include paints, inks, cosmetics, fillers for toothpaste and the like. When steelmaking slag is used as a raw material, CaCO ₃ obtained in the present invention and SiO ₂ produced as a by-product can be effectively used in various industrial fields.

Further, in the present step C, when the carbon dioxide gas in the exhaust gas is immobilized by using the exhaust gas containing a harmful substance such as SOx, NOx as the gas containing the carbon dioxide gas, the SOx, NOx acts as an acid together with HCl, contributing to the promotion of the dissolution reaction of alkaline earth metal-containing substances, and at the same time, SOx is immobilized as CaSO ₄ (gypsum) and detoxified.

As described above, FIGS. 1 and 2 are schematic flow charts from the extraction of the alkaline earth metal of the present invention to the recovery of iron and the immobilization of carbonate. Here, a verification test was conducted on a laboratory scale according to the process flow of FIG. This verification test will be described by classifying it into each of step A, step B, and step C, which are elements constituting the flow.

[Step A]
First, the examination results for step A will be described.
In step A, an alkaline earth metal extraction operation was carried out. That is, in order to examine the optimum conditions for the extraction operation of alkaline earth metal, four operations of (a) the regulation degree of the amine-hydrochloric acid mixed aqueous solution, (b) the amount of the extract, (c) the extraction temperature, and (d) the extraction time. A parameter test was conducted with the contents shown in Table 1 for the effect of variables on the extraction behavior. The substance containing alkaline earth metal and valuable material (iron) used in the test was steelmaking slag, and its particle size was less than 425 μm. The test apparatus for the extraction operation has the configuration shown in FIG.

Here, the composition of the steelmaking slag was identified by analyzing the metal elements contained by ICP emission spectroscopic analysis. Regarding the composition analysis results of decarburized slag converted to oxides with respect to the weight ratio of each obtained composition, the main components are shown in Table 2, and among the other elements contained in Table 2, the ministerial ordinance that sets the wastewater standard ( The elements listed in Appendix 1 of the Ministry of the Environment Ordinance No. 15 of the first year of Reiwa are shown in Table 3 as trace components. The balance of substance weight is calculated using only the main components and does not include trace components.

The operation procedures 1 to 7 of the alkaline earth metal extraction operation are shown below.
1. As the extract, 35 mass% HCl (manufactured by Wako Pure Chemical Industries, Ltd .: Code No. 089-07555) and DEA (manufactured by Tokyo Kasei Co., Ltd .: product code I0008) are mixed at a molar ratio of 1: 1 and 1 liter (1 l) in a volumetric flask. Dilute to liter) to prepare an amine-hydrochloric acid mixed aqueous solution containing HCl and DEA according to their respective specifications (N).
2. The extract bml was poured into a three-necked flask (13 in FIG. 3) having a capacity of 200 ml, stirred with a magnetic stirrer at 800 rpm, and the temperature of the water bath 14 was set to c ° C.
3. After the temperature of the water bath 14 reached the set temperature, a sample of 5.25 g of steel slag was put into a three-necked flask and plugged. A straight tube type cooling tube (11 in Fig. 3) with a length of 15 cm is attached to the side opening of the three-necked flask, and tap water is circulated through the cooling tube to cool it, thereby refluxing the components volatilized from the extract. rice field. The temperature of the water bath 14 was constantly checked with a thermometer.
4. After d minutes, the entire suspension in the three-necked flask is taken out, filtered through a membrane filter having a pore size of 1.0 μm, and the filtrate (corresponding to the alkaline earth metal extract in FIG. 2) and the residue 1 (in FIG. 2). (Corresponding to residue 1) was obtained.
5. The slag residue was dried in a constant temperature bath at 60 ° C. and analyzed by ICP.
6. The volume of 10 ml of the above filtrate was adjusted to 50 ml with a 5% aqueous nitric acid solution and analyzed by ICP.

In the above alkaline earth metal extraction operation, the basic conditions for Ca extraction under the conditions of No. 4 in Table 1 {(a) 1.02N, (b) 90 ml, (c) 80 ° C, (d) 30 min}. And said.

The residue 1 and the alkaline earth metal extract produced under the conditions of No. 4 in Table 1 were used in the following steps B and C to carry out the subsequent tests.

[Step B]
Next, the examination result for step B will be described.
In step B, a study was conducted to obtain an iron recovered product (residue 2: corresponding to the residue 2 in FIG. 2) as a valuable resource from the above residue 1. That is, a method of dissolving an unnecessary component from the residue 1 and leaving the iron component on the solid side to increase the purity was investigated. After drying the residue 1 in a constant temperature bath at 60 ° C, the main components of the results analyzed by ICP are shown in Table 4, and among the other elements contained in Table 4, the ministerial ordinance (Reiwa) that sets the wastewater standard. 1st year Ministry of the Environment Ordinance No. 15) The elements listed in Attached Table 1 are shown in Table 5 as trace components.
The test apparatus for the extraction operation here has the configuration shown in FIG. In this step, the relationship between the recovered Fe-containing Fe concentration and the extraction time when the pH of the extract is different shows the behavior as shown in FIG.

The work procedures 1 to 6 for recovering the iron recovered product (residue 2) from the residue 1 are shown below.
1. For the extract, mix 35 mass% HCl (Wako Pure Chemical Industries, Ltd., 089-07555) and HF at a molar ratio of 1: 1 and dilute to 1 liter (liter) in a volumetric flask to add 1.02 of each of HCl and HF. A mixed aqueous solution containing (N) was prepared.
2. 90 ml of the extract was poured into a three-necked flask (13 in FIG. 3) having a capacity of 200 ml, stirred with a magnetic stirrer at 800 rpm, and the temperature of the water bath 14 was set to 80 ° C.
3. After the temperature of the water bath 14 reached the set temperature, 3.74 g of a steel slag sample was put into a three-necked flask and plugged. A straight tube type cooling tube (11 in Fig. 3) with a length of 15 cm is attached to the side opening of the three-necked flask, and tap water is circulated through the cooling tube to cool it, thereby refluxing the components volatilized from the extract. rice field. The temperature of the water bath 14 was constantly checked with a thermometer.
After 4.d minutes, the entire suspension in the three-necked flask was taken out and filtered through a membrane filter having a pore size of 1.0 μm to obtain a filtrate and a residue 2.
5. The above residue 2 was dried in a constant temperature bath at 60 ° C. and then analyzed by ICP. Regarding the results of this analysis, the main components are shown in Table 6, and among the elements contained in the others in Table 6, the elements listed in Appendix 1 of the Ministerial Ordinance (Reiwa 1st Year Environment Ministry Ordinance No. 15) that establishes wastewater standards. , Are shown in Table 7 as trace components.
6. The volume of 10 ml of the above filtrate was adjusted to 50 ml with a 5% aqueous nitric acid solution and analyzed by ICP.

As shown in Tables 6 and 7 of the above analysis results of the residue 2, it was confirmed that about 80 mass% of iron oxide can be recovered by converting the iron component contained in the residue 2 into an oxide. This indicates that the weight ratio of iron oxide contained in the residue 1 is increased by about 50 mass%. Incidentally, in order to improve the ratio of iron, a method such as increasing the concentration of the solvent and the solid-liquid ratio can be considered.

[Process C]
Further, the examination result for the process C will be described.
Regarding step C, a study was conducted to recover the alkaline earth metal carbonate by contacting the alkaline earth metal extract recovered in the above step A with carbon dioxide gas. Using the test apparatus shown in FIG. 5, the filtrate (alkaline earth metal extract) obtained in the alkaline earth metal extraction operation of step A is used as a CO ₂ absorbing solution (mixed aqueous solution of CaCl ₂ and DEA). Then, the alkaline earth metal carbonate was crystallized by contacting the CO ₂ absorbing solution with CO ₂ (a gas containing carbon dioxide gas). This crystallization operation was carried out in steps 1 to 4 below.

1. Pour 70 ml of CO ₂ absorbent into a three-necked flask with a capacity of 200 ml (13 in Fig. 5), place it in a water bath adjusted to 40 ° C (14 in Fig. 5), and place it in a magnetic stirrer (in Fig. 5). It was stirred at 800 rpm according to 15). A straight tube type cooling tube (11 in Fig. 5) with a length of 15 cm is attached to the side opening of the three-necked flask, and tap water is circulated through the cooling tube to cool it, thereby refluxing the components volatilized from the extract. rice field. The temperature of the water bath 14 was constantly checked with a thermometer.
2. After the temperature of the water bath 14 reached the set temperature, CO ₂ (99.999%) gas was blown from the gas blowing pipe (16 in FIG. 5) at a flow rate of 90 ml / min to react with the CO ₂ absorbing liquid. The reaction time was 60 minutes. 3. After 60 minutes, the gas injection was stopped, and the entire amount of the obtained suspension was filtered off by a membrane filter (pore size 1.0 μm) to obtain crystallized cake (CaCO ₃ ) and a filtrate.
4. The crystallization cake was dried in an electric furnace at 60 ° C., and then weighed to determine the amount of CO ₂ absorbed and the amount of precipitated alkaline earth metal (Ca). Regarding the results, the main components are shown in Table 8, and among the elements contained in the others in Table 8, the elements listed in Appendix 1 of the Ministerial Ordinance (Reiwa 1st Year Environment Ministry Ordinance No. 15) that establishes wastewater standards It is shown in Table 9 as a trace component.

In analyzing the composition of the crystallization cake obtained according to the above by ICP emission spectroscopic analysis, the mixed acid aqueous solution was used as an acid solvent as a pretreatment, and the crystallization cake was completely processed using a microwave heating device (MARS6 manufactured by CEM). Dissolved. The samples obtained by total dissolution were analyzed by ICP emission spectroscopic analysis using Agilent 5110 ICP-OES and Agilent SPS4 Autosampler. The total dissolution operation and analysis were performed in steps 1-7 below.

1. 0.25 g of crystallization cake was added to a reaction cell made of fluororesin, and 12 ml of a mixed acid aqueous solution prepared by mixing 8 ml of a 35 mass% HCl aqueous solution and 4 ml of an HNO ₃ 70 mass% aqueous solution was added as an acid solvent. ..
2. The reaction cell was tightly sealed and set in a microwave heating device.
3. The temperature was raised to 230 ° C. in 10 minutes, held for 2 hours, and then cooled to about room temperature.
4. The solution in the reaction cell was transferred to a 25 mL volumetric flask and the volume was adjusted with a 5 mass% nitric acid aqueous solution. This was used as the stock solution for the analysis sample.
5. 1 ml of the stock solution of the analytical sample was taken and added to a 100 ml volumetric flask, and the volume was adjusted with a 5 mass% nitric acid aqueous solution.
6. The stock solution of the analysis sample was separated by 10 ml, added to a 100 ml volumetric flask, and the volume was adjusted with a 5 mass% nitric acid aqueous solution.
7. The above analysis sample stock solution and diluted solution were analyzed by ICP emission spectroscopic analysis.

As the results of the above analysis are shown in Tables 8 and 9, the composition ratio of CaCO ₃ was 97.2 mass%, and there was almost no contamination with trace metals. Further, FIG. 6 shows the results of observing the generated CaCO ₃ with a scanning electron microscope (SEM), and FIG. 7 shows the results of analyzing the composition by an X-ray diffraction method (XRD). As shown in these figures, it was confirmed that the produced CaCO ₃ is the most stable hexagonal calcite.

From the above results, it can be seen that by applying the present invention to, for example, a steel mill, it becomes possible to make valuable use as a new iron source by relatively increasing the proportion of iron components contained in slag. Furthermore, it was confirmed that the immobilization of carbon dioxide gas discharged from various factories and various processes of steelworks as a carbonate can be easily realized.

1 Residue 2 Residue 11 Cooling tube 12 PH electrode 13 Three-necked flask 14 Water bath 15 Stirrer 16 Gas inlet

Claims (11)

A substance containing an alkaline earth metal and a valuable substance is brought into contact with an aqueous solution containing a salt of a weak base and a strong acid to form an alkaline earth metal extract and a residue, and the alkaline earth metal extract and the residue are separated. And the process to do
Alkaline earth metals and valuables, comprising contacting the residue with an aqueous solution containing a salt of a strong acid to leach components other than valuables into the aqueous solution to increase the proportion of iron in the residue. A method for treating a substance containing. A substance containing an alkaline earth metal and a valuable substance is brought into contact with an aqueous solution containing a weak base and a salt of a strong acid to form an alkaline earth metal extract and a residue, which are separated into an alkaline earth metal extract and a residue. And the process to do
A step of contacting a gas containing carbon dioxide with the alkaline earth metal extract to generate a carbonate,
Alkaline earth metals and valuables, comprising contacting the residue with an aqueous solution containing a salt of a strong acid to leach components other than valuables into the aqueous solution to increase the proportion of valuables in the residue. A method for treating substances containing substances. The method for treating a substance containing an alkaline earth metal and a valuable resource according to claim 2, wherein the gas containing carbon dioxide is an exhaust gas discharged from a manufacturing facility. The method for treating a substance containing an alkaline earth metal and a valuable resource according to claim 2, wherein the gas containing carbon dioxide gas contains NOx or SOx. The alkaline earth metal according to any one of claims 1 to 4, wherein the substance containing the alkaline earth metal and valuable resources is at least one of natural minerals, waste materials, and by-products discharged in the manufacturing process. And how to treat substances containing valuables. 13. A method for treating substances containing alkaline earth metals and valuable resources. The substance containing the alkaline earth metal and the valuable material according to any one of claims 1 to 4, wherein the substance containing the alkaline earth metal and the valuable material is a steel slag discharged in the steelmaking process or the steelmaking process. Processing method. The alkaline earth metal and valuables according to any one of claims 1 to 7, wherein the valuables are at least one of iron, magnesium, silicon, aluminum, manganese, phosphorus, cadmium, lead, boron and arsenic. A method for treating a substance containing. A substance containing an alkaline earth metal and a valuable substance is brought into contact with an aqueous solution containing a weak base and a salt of a strong acid to form an alkaline earth metal extract and a residue, which are separated into an alkaline earth metal extract and a residue. And the process to do
A step of bringing the residue into contact with an aqueous solution containing a salt of a strong acid, leaching components other than valuables into the aqueous solution, and recovering the residue from which the components other than the valuables have been removed as valuables.
A method for recovering valuable resources from substances containing alkaline earth metals and valuable resources. The alkaline earth metal according to claim 9, wherein the substance containing the alkaline earth metal and the valuable material is at least one of pyroxene, amphibole, ankerite, pomegranate stone, green brick stone and fluffy stone. A method for recovering valuable resources from substances containing iron. The alkaline earth metal and valuables according to claim 9 or 10, wherein the valuables are at least one of iron, magnesium, silicon, aluminum, manganese, phosphorus, cadmium, lead, boron and arsenic. How to recover valuables from substances.

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