Method for producing phosphorus compounds

Abstract

To provide a method for producing a phosphorus compound that, by further improving a method for purifying a phosphorus compound, can efficiently produce a high-purity phosphorus compound from a solid material containing a phosphorus compound and a silicon compound and having a specific element content.SOLUTION: A method for producing a phosphorus compound for producing a phosphorus compound from a solid material containing a phosphorus compound and a silicon compound and having a calcium element content of 20 mass% or less, comprises a dissolution treatment step of dissolution-treating the solid material using an acid to obtain a phosphorus compound solution. This makes it possible to efficiently obtain a high-purity phosphorus compound.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a phosphorus compound. More specifically, the present invention relates to a method for producing a phosphorus compound from a solid material derived from dephosphorization slag or the like. [Background technology]

[0002] Phosphorus is used not only in the agricultural field, but also in various fields such as the food field, high technology field, pharmaceutical and chemical fields, etc. Currently, phosphorus is mainly obtained from natural phosphate rock, which is mainly composed of calcium hydroxyapatite and calcium phosphate, but in recent years, there has been concern about the depletion of natural phosphate rock, and other methods for obtaining phosphorus resources are being sought.

[0003] Another method for obtaining phosphorus resources is to recover unused phosphorus resources from waste materials, etc. Examples of waste materials include dephosphorized slag obtained as waste from steelmaking, industrial waste, and wastewater.

[0004] For example, Patent Document 1 describes a method in which calcium is removed from dephosphorization slag, phosphorus is eluted from the residual slag using sulfuric acid, and the phosphorus eluate is neutralized with calcium hydroxide or a solution thereof to precipitate calcium-containing phosphates. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2020-018951 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with conventional methods, it has been difficult to efficiently remove other elements, such as silicon compounds, which are present in high concentrations in waste materials, during purification, making it difficult to improve the purity of the phosphorus compound.

[0007] Therefore, an object of the present invention is to provide a method for producing a phosphorus compound, which can efficiently produce a phosphorus compound of high purity from a solid material containing a phosphorus compound and a silicon compound and having a specific element content, by further improving the purification method of the phosphorus compound. [Means for solving the problem]

[0008] As a result of intensive research into the above-mentioned problems, the inventors have discovered that in the purification of phosphorus compounds, a phosphorus compound of high purity can be efficiently obtained by including a dissolution treatment step in which a solid material containing a phosphorus compound and a silicon compound and having a calcium element content of 20 mass% or less is dissolved using an acid to obtain a phosphorus compound solution, and have completed the present invention. That is, the method for producing a phosphorus compound is as follows.

[0009] [1] A method for producing a phosphorus compound, comprising the steps of: producing a phosphorus compound from a solid material containing a phosphorus compound and a silicon compound and having a calcium element content of 20 mass% or less, A method for producing a phosphorus compound, comprising a dissolution treatment step of dissolving the solid material with an acid to obtain a phosphorus compound solution. This makes it possible to efficiently obtain a phosphorus compound with high purity. [2] The method for preparing a phosphorus compound according to [1], characterized in that the acid used in the dissolution treatment step is nitric acid or hydrochloric acid. This makes it possible to more efficiently obtain a phosphorus compound with high purity. [3] The method for producing a phosphorus compound according to [1] or [2], further comprising a cation exchange step of treating the obtained phosphorus compound solution with a cation exchange resin. This makes it possible to obtain a phosphorus compound with even higher purity. [4] The method for producing a phosphorus compound according to any one of [1] to [3], wherein the solid is obtained by the following steps: (iA) Extracting phosphorus compounds from dephosphorization slag using an acid (ii) A step of adjusting the pH of the obtained phosphorus compound extract by adding an alkali to obtain a precipitate as a solid. This makes it possible to efficiently obtain a large amount of phosphorus compounds at low cost. [5] The method for producing a phosphorus compound according to any one of [1] to [3], wherein the solid is obtained by the following steps: (iB) A step of charging various substances containing phosphorus and iron elements into a melting furnace, charging and reducing auxiliary materials containing silicon as necessary, concentrating phosphorus as phosphorus element, and dissolving the artificial phosphate rock obtained by the reduction in acid to extract phosphorus compounds. (ii) A step of adjusting the pH of the obtained phosphorus compound extract by adding an alkali to obtain a precipitate as a solid. This makes it possible to efficiently obtain a larger amount of phosphorus compound at a lower cost. [6] The method for producing a phosphorus compound according to [4] or [5], characterized in that the acid used in the step (i) is nitric acid or hydrochloric acid. This makes it possible to increase the amount of phosphorus compounds in the phosphorus compound extract, and to obtain a larger amount of phosphorus compounds at a lower cost. [7] A method for producing a silicon compound, comprising the steps of: producing a silicon compound from a solid material containing a phosphorus compound and a silicon compound and having a calcium element content of 20 mass% or less, A method for producing a silicon compound, comprising an acid treatment step of treating the solid with an acid and then removing the supernatant to obtain the silicon compound as a solid. This makes it possible to efficiently obtain a silicon compound with high purity. Effect of the Invention

[0010] According to the present invention, by further improving the method for purifying a phosphorus compound, it is possible to provide a method for producing a phosphorus compound, which can efficiently produce a phosphorus compound of high purity from a solid material containing a phosphorus compound and a silicon compound and having a specific element content. [Brief description of the drawings]

[0011] [Figure 1] 1 is a flowchart showing an example of a method for producing a phosphorus compound using dephosphorization slag as a raw material. [Diagram 2] 4 shows the XRD pattern of dephosphorization slag. [Diagram 3] 4 shows the XRD pattern of the solid before the dissolution treatment step. [Figure 4] 4 shows the XRD pattern of the residue after the dissolution treatment step. [Diagram 5] The NMR spectrum of the solution obtained by cation exchange resin treatment and orthophosphoric acid is shown. [Figure 6] 4 shows the XRD patterns of the precipitate before and after calcination. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The production method described below is merely an example for explaining the production method according to the present invention, and is not limited thereto.

[0013] [Method of producing phosphorus compounds] The method for producing a phosphorus compound according to the present invention is a method for producing a phosphorus compound from a solid material containing a phosphorus compound and a silicon compound and having a calcium element content of 20 mass% or less, and is characterized in that it includes a dissolution treatment step of dissolving the solid material using an acid to obtain a phosphorus compound solution. In the production of phosphorus compounds, by including the above-mentioned dissolution treatment step, it is possible to efficiently obtain phosphorus compounds of high purity, such as orthophosphoric acid and calcium phosphate. In addition, since silicon compounds do not dissolve in the dissolution treatment step and remain in the residue, the silicon compounds can be removed by removing the solid, for example, by solid-liquid separation. Similarly, calcium element can be efficiently removed by the above-mentioned dissolution treatment step.

[0014] (Dissolution processing step) The dissolution treatment step is characterized in that a solid having a specific elemental composition is dissolved using an acid to obtain a phosphorus compound solution.

[0015] The solid material targeted in the dissolution treatment step is a solid material containing a phosphorus compound and a silicon compound, and having a specific element content in terms of the calcium element content. The calcium element content is, for example, 20 mass% or less, preferably 15 mass% or less, and more preferably 10 mass% or less. By setting the calcium element content within the above range, the method of the present invention can more efficiently obtain a phosphorus compound with high purity.

[0016] The elements and compounds in the solid or residue are analyzed using X-ray analysis, and elemental analysis can be performed by X-ray fluorescence analysis (XRF) and compound analysis by powder X-ray diffraction (XRD). The element or compound content of the phosphorus compound solution can be measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). In order to analyze the composition of a solid with low crystallinity or in an amorphous state, a solid with high crystallinity is usually calcined.

[0017] The solid to be treated in the dissolution step is not particularly limited, but preferably has low crystallinity and is preferably in an amorphous state. The low crystallinity or amorphous state can be confirmed by the fact that no clear peak is measured when the obtained solid is directly measured by XRD. By setting the crystallinity within the above numerical range, a phosphorus compound with high purity can be obtained more efficiently. The solid is, for example, a crude product after initial or intermediate purification, and from the viewpoint of obtaining a solid with low crystallinity, the solid is preferably formed by treatment at room temperature, for example, precipitation, reprecipitation, etc.

[0018] The acid used in the dissolution step is not particularly limited, and may be, for example, an inorganic acid or an organic acid. Examples of inorganic acids include nitric acid, hydrochloric acid, boric acid, and hydrofluoric acid. Examples of organic acids include citric acid, acetic acid, formic acid, and oxalic acid. Among these, from the viewpoint of increasing the yield and purity of the phosphorus compound, preferred are nitric acid and hydrochloric acid, and more preferred is nitric acid.

[0019] The pH of the acid used in the dissolution treatment step is not particularly limited and is, for example, not more than pH 4. From the viewpoint of production efficiency of the phosphorus compound, the upper limit is preferably not more than pH 3, more preferably not more than pH 2, and further preferably not more than pH 1.

[0020] The volume of the acid used in the dissolution step is not particularly limited, and is, for example, 5 to 2000 mL per 1 g of solid matter. The lower limit is preferably 10 mL or more, and more preferably 20 mL or more. The upper limit is 1000 mL or less, and 500 mL or less. By setting the volume of the acid within the above range, production efficiency can be improved.

[0021] The phosphorus element content in the phosphorus compound solution obtained by the dissolution treatment step is, for example, 5% or more, preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. The silicon element content in the phosphorus compound solution obtained is, for example, 20% by mass or less, preferably 10% by mass or less, and more preferably 5% by mass or less.

[0022] (Cation exchange step) The method for producing a phosphorus compound according to the present invention preferably includes a cation exchange step of treating the obtained phosphorus compound solution with a cation exchange resin. By including the cation exchange step in the method for producing a phosphorus compound, cations, particularly metal cations, can be efficiently removed. Examples of metal cations to be removed include iron ions, calcium ions, magnesium ions, and manganese ions. This step removes cations from the phosphorus compound solution, and the concentration of cations after the treatment is, for example, 40% or less, preferably 20% or less, more preferably 10%, and even more preferably 5% or less, of the concentration before the treatment.

[0023] The cation exchange resin is not particularly limited, and examples thereof include strong acid cation exchange resins and weak acid cation exchange resins. Strong acid cation exchange resins include those having a sulfo group as an exchange group. Weak acid cation exchange resins include those having a carboxyl group as an exchange group. Among these, strong acid cation exchange resins having a sulfo group as an exchange group are preferred, and specifically, Diaion (registered trademark) PK216LH (manufactured by Mitsubishi Chemical Corporation) and the like are included.

[0024] The solution resulting from the cation exchange step preferably contains orthophosphoric acid, the purity of which in the solution is, for example, 60% or more, preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0025] (Other steps) The method for producing a phosphorus compound according to the present invention may further include other steps, including, but not limited to, a calcium phosphate precipitation step, a calcination step, and the like.

[0026] The calcium phosphate precipitation step is a step in which a calcium salt is added to the solution containing orthophosphoric acid obtained by the above step to obtain a calcium phosphate precipitate. The calcium phosphate precipitation step preferably involves pH adjustment from the viewpoint of facilitating precipitation of solid matter. The pH targeted for pH adjustment in the calcium phosphate precipitation step is not particularly limited, but is pH 2 or higher. The lower limit is preferably 4 or higher, and more preferably 6 or higher. By adding an alkali to adjust the pH to within the above range, a solid matter can be effectively obtained as a precipitate.

[0027] The salt used in the calcium phosphate precipitation step is a calcium salt. Examples of such calcium salts include calcium nitrate, calcium hydroxide, calcium chloride, etc. Among these, calcium nitrate and calcium chloride are preferred, and calcium nitrate is more preferred, from the viewpoints of not significantly affecting pH and having high solubility.

[0028] The calcination step is a step of obtaining crystals of the phosphorus compound by calcining the obtained precipitate. It can be performed following a step of obtaining a solid phosphorus compound, such as a calcium phosphate precipitation step or a pH adjustment step. The calcination temperature is not particularly limited, but is, for example, 873 to 1223 K. The upper limit is preferably 1173 K or less, more preferably 1123 K or less. The lower limit is preferably 973 K or more, more preferably 1023 K or more.

[0029] In addition, the solid material used in the method for producing a phosphorus compound according to the present invention is preferably obtained by the following steps. (iA) Extracting phosphorus compounds from dephosphorization slag using an acid (ii) A step of adjusting the pH of the obtained phosphorus compound extract by adding an alkali to obtain a precipitate as a solid. By using the above solid matter as a raw material for producing a phosphorus compound, a large amount of the phosphorus compound can be efficiently obtained at low cost.

[0030] Since dephosphorization slag is a solid produced in the high-heat environment of the steelmaking process, it is highly crystalline and it is not appropriate to apply the dissolution treatment step of the present invention described above. However, the effects of the present invention can be obtained by producing a solid material through the above steps (i) and (ii) and then applying the dissolution treatment step.

[0031] Step (iA) is a step of extracting phosphorus compounds from the dephosphorization slag with an acid.

[0032] The acid used in step (iA) is not particularly limited, and for example, an inorganic acid or an organic acid is used. Examples of inorganic acids include nitric acid, hydrochloric acid, boric acid, and hydrofluoric acid. Examples of organic acids include citric acid, acetic acid, formic acid, and oxalic acid. Among these, from the viewpoint of increasing the yield and purity of the phosphorus compound, preferred are nitric acid and hydrochloric acid, and more preferred is nitric acid.

[0033] The acid concentration is not particularly limited, but is, for example, 0.01 M to 10 M. The upper limit is 5 M or less, and more preferably 2 M or less. The lower limit is preferably 0.05 M or more, and more preferably 0.1 M or more. By setting the acid concentration within the above range, phosphorus compounds can be more effectively extracted from the dephosphorization slag.

[0034] Step (ii) is a step of adjusting the pH of the obtained phosphorus compound extract by adding an alkali to obtain a precipitate as a solid. The pH to be adjusted is pH 3 or more from the viewpoint of facilitating obtaining a solid. The lower limit is more preferably pH 4 or more. The upper limit is preferably pH 7 or less, more preferably pH 5 or less. By adding an alkali to adjust the pH to within the above range, a solid can be effectively obtained as a precipitate.

[0035] The alkali used in step (ii) is not particularly limited, but an inorganic alkali can be used. Examples of inorganic alkali include ammonia water (NH4OH), sodium hydroxide, potassium hydroxide, magnesium hydroxide, etc. Among these, ammonia water, sodium hydroxide, and potassium hydroxide are preferred, and ammonia water is more preferred.

[0036] Instead of the above-mentioned dephosphorization slag, the solid material used in the present invention can also be produced using artificial phosphate rock as described in Japanese Patent No. 5907834. In this case, the solid material used in the method for producing a phosphorus compound is preferably obtained by the following steps. (iB) A step of charging a material containing phosphorus and iron elements into a melting furnace, charging and reducing an auxiliary material containing silicon as necessary, concentrating phosphorus as phosphorus element, and dissolving the artificial phosphate rock obtained by dissolving it in acid to extract phosphorus compounds obtained. (ii) A step of adjusting the pH of the obtained phosphorus compound extract by adding an alkali to obtain a precipitate as a solid. When artificial phosphate rock is used, the phosphorus concentration is much higher than that of dephosphorization slag, so phosphorus compounds can be obtained more efficiently and economically. The conditions in each step of the production of the solid can be the same as those in steps (iA) and (ii) in the case of dephosphorization slag described above.

[0037] The artificial phosphate rock is produced by charging various substances containing phosphorus and iron into a melting furnace, and optionally charging and reducing auxiliary materials containing silicon to concentrate phosphorus as elemental phosphorus, thereby producing phosphorus-containing iron, which can efficiently recover phosphorus contained in the phosphorus raw material. For example, since the phosphorus-containing iron has an increased content due to the concentration of phosphorus, it can be used as a substitute for natural phosphate rock, i.e., as artificial phosphate rock. By using dephosphorized slag or sewage sludge as the phosphorus raw material, it can contribute to the effective recycling of iron, manganese, and the like in addition to phosphorus.

[0038] The phosphorus raw material is an industrial waste or by-product containing phosphorus, and specifically, dephosphorized slag, sewage sludge, etc. can be used. As mentioned above, dephosphorized slag has a sufficient phosphorus content and is generated in large quantities, so it is preferable to use dephosphorized slag as the phosphorus raw material for artificial phosphorus phosphate ore from the viewpoint of ensuring a stable supply of phosphorus raw material. In addition, dephosphorized slag itself contains iron, so it can be said to be a more preferable raw material.

[0039] As the iron raw material, iron scrap or crude steel can be used, but from the viewpoint of reusing resources, it is preferable to use iron scrap, which is an industrial waste.

[0040] In order to adjust the basicity of the molten slag produced together with the molten iron, a silicon raw material or a calcium raw material is charged into the melting furnace as necessary. As the silicon raw material, for example, silica stone, silica sand, waste glass, silicon scraps, and SiC scraps can be used. Here, the silicon scraps are chips containing silicon, including sludge-like chips. Specifically, the chips include chips generated when processing silicon wafers for solar panels by chemical mechanical polishing or the like, and chips generated during the manufacture of liquid crystal displays and the processing of silicon wafers for semiconductor devices. SiC is used in devices such as transistors in harsh environments, and the chips generated during the production of these devices are SiC scraps. From the viewpoint of reusing industrial waste, it is preferable to use waste glass, silicon scraps, and SiC scraps as the silicon raw material.

[0041] The carbonaceous material is a solid material mainly composed of carbon, which reacts with the combustion-supporting gas. For example, coke, charcoal, biomass, RDF, waste wood, waste pulp, and pulverized coal can be used as the carbonaceous material. Here, "RDF" is an abbreviation for "Refuse Derived Fuel" and means a carbonaceous material derived from waste. The carbonaceous material may contain a non-solid carbonaceous material, such as coal tar or pitch, or may contain coal, as long as it is usable in a melting furnace.

[0042] The phosphorus raw material, the iron raw material, the silicon raw material and the carbonaceous material may each be used alone or in combination of two or more kinds at a predetermined ratio.

[0043] Melting furnaces include shaft-type carbon packed bed type, kiln type, and electric furnace type.

[0044] In addition, commercially available iron phosphate can also be used as a raw material for the solid material, similar to the above-mentioned artificial phosphate rock and dephosphorization slag. In this case, the iron phosphate can be dissolved in acid to extract phosphorus compounds, and then the solid material can be produced by carrying out the above-mentioned step (ii) treatment.

[0045] [Method of producing silicon compounds] The method for producing a silicon compound according to the present invention is a method for producing a silicon compound from a solid material containing a phosphorus compound and a silicon compound and having a calcium element content of 20 mass% or less, and is characterized in that it includes an acid treatment step in which the solid material is treated with an acid and then the supernatant is removed to obtain the silicon compound as a solid. This makes it possible to efficiently produce a silicon compound with high purity. The method for producing a silicon compound can be carried out using the same acid and under the same conditions as in the dissolution treatment step of the method for producing a phosphorus compound described above.

[0046] The silicon compound obtained by the present production method includes, for example, amorphous silica, etc. The purity of the silicon compound obtained by the present production method is, for example, 60% or more, preferably 80% or more, more preferably 90% or more, and further preferably 95% or more. EXAMPLES

[0047] The present invention will be described in more detail below with reference to examples. However, these are merely illustrative and the present invention is not limited to these descriptions.

[0048] (1) Purification of phosphorus compounds from dephosphorization slag The following is an example of an experiment in which a solid was obtained using dephosphorization slag as a raw material, and orthophosphoric acid and calcium phosphate were obtained through manufacturing steps such as a dissolution treatment step and a cation exchange step. Figure 1 shows the overall image of the experiment.

[0049] (Preparation of solids) The raw material used was dephosphorization slag with the elemental composition shown in Table 1 and the XRD pattern shown in Figure 1. First, the dephosphorization slag was ground and sieved to 355 μm or less. Next, 100 mL of 0.5 M nitric acid was prepared in a 200 mL Erlenmeyer flask, and 1.00 g of the sieved dephosphorization slag was added to extract phosphorus compounds. The extraction was performed at 293 K and 130 rpm for 0.2 hours. After the extraction of phosphorus compounds, the solution was filtered to separate the eluate (100 mL) from the residue. The eluate was analyzed by ICP-AES, and the residue was analyzed by XRF. The results of the ICP-AES analysis of the eluate and the XRF analysis of the residue are shown in Table 2 and Table 3, respectively. The phosphorus extraction rate from the dephosphorization slag was 86%, as compared to the phosphorus content (0.68 nmol / g-slag) of the dephosphorization slag measured by dissolving the dephosphorization slag in aqua regia and HF.

[0050] [Table 1]

[0051] [Table 2]

[0052] [Table 3]

[0053] Next, ammonia water was added to the eluate to adjust the pH to 4, thereby forming a precipitate. The precipitate was formed by stirring at 200 rpm for 30 minutes at room temperature, followed by leaving it to stand for 30 minutes. The precipitate and the filtrate were then separated by filtration, and dried at 353 K for 24 hours to obtain 0.363 g of precipitate (solid matter) containing phosphorus compounds. The results of the XRF analysis of the solid matter are shown in Table 4, and the XRD patterns of the solid matter before and after calcination are shown in Figure 3. Figure 3 shows that the solid matter before calcination had no clear peaks, indicating that it was in an amorphous state.

[0054] [Table 4]

[0055] (Solid matter dissolution treatment) The solid produced by the above procedure was dissolved in 100 mL of 0.5 M nitric acid. Dissolution was performed by stirring at 200 rpm at room temperature for 1 hour. After stirring, the mixture was filtered to separate 95 mL of acid eluate (phosphorus compound solution) and 0.118 g of residue. The results of ICP-AES analysis of the acid eluate are shown in Table 5, and the results of XRD analysis of the residue are shown in Figure 4.

[0056] [Table 5]

[0057] [Table 6]

[0058] It was confirmed from Table 6 that silicon compounds could be largely removed by dissolution treatment with acid. Since silicon compounds cannot be detected by ICP-AES analysis, it is difficult to quantify the amount of silicon compounds in the acid eluate, but it can also be confirmed from the composition in Table 9 that silicon compounds could be largely removed in this step. XRD confirmed that the residual silicon compound was amorphous silica.

[0059] (cation exchange treatment) The eluate obtained by the dissolution treatment was further treated with a cation exchange resin. A burette was filled with glass wool and 5.00 g of a strong acid cation exchange resin (PK216LH, manufactured by Mitsubishi Chemical Corporation), and the eluate was introduced into the burette at a flow rate of 2.5 mL / min using a pump. 95 mL of the solution was collected 2 minutes after the introduction. The collected solution was analyzed by ICP-AES and 31 The results of the ICP-AES analysis after the cation exchange treatment are shown in Table 7, the NMR spectrum is shown in the upper panel of Figure 5, and the NMR spectrum of orthophosphoric acid is shown in the lower panel of Figure 5.

[0060] [Table 7]

[0061] [Table 8]

[0062] As shown in Table 7, the cation exchange treatment resulted in the production of phosphorus compounds of very high purity. Furthermore, when the NMR spectrum of the eluate was compared with that of orthophosphoric acid, no other peaks were detected, confirming that the eluate was orthophosphoric acid (H3PO4) of high purity. Furthermore, as shown in Table 8, the production of phosphorus compounds, i.e., orthophosphoric acid, by the method of this example had a high recovery rate of about 78% compared to the stage of the dephosphorization slag extract. By the method of this example, 47 mg of orthophosphoric acid could be purified from 1.00 g of dephosphorization slag.

[0063] (Calcium phosphate production) 0.236 g of calcium nitrate tetrahydrate was added as a calcium source to 50 mL of the solution after the cation exchange treatment to neutralize it, and then the pH of the solution was adjusted to 7 using ammonia water to generate a precipitate. The precipitate was generated by stirring at 200 rpm for 30 minutes at room temperature and then leaving it to stand for 30 minutes. The precipitate was then collected by filtration and dried at 353 K for 24 hours. After drying, the precipitate was calcined at 1073 K for 5 hours to increase the crystallinity, and calcium phosphate crystals were obtained. The results of the XRF analysis of the obtained calcium phosphate crystal precipitate are shown in Table 9, and the XRD patterns before and after calcination are shown in Figure 6.

[0064] [Table 9]

[0065] From the XRD pattern in Figure 6, the main component of the precipitate before firing is calcium hydroxyapatite (Ca 10 It was confirmed that the calcium phosphate crystals (Ca3(PO4)2) were formed after firing. In addition, it was confirmed from FIG. 6 and Table 9 that calcium phosphate with a high purity of 95% or more was obtained.

[0066] (2) Refining phosphorus compounds from artificial phosphate rock The following is an example of an experiment in which artificial phosphate rock is produced, a solid is obtained using the artificial phosphate rock as a raw material, and orthophosphoric acid is obtained through production steps such as a dissolution treatment step and a cation exchange step.

[0067] (Manufacturing of artificial phosphate rock) The iron raw material was charged together with the phosphorus raw material, silicon raw material, and carbonaceous material, and melted. The molten iron with concentrated phosphorus was discharged to obtain phosphorus-containing iron (artificial phosphate rock). The iron raw material was charged into a melting furnace along with the phosphorus raw material, silicon raw material and carbonaceous material and melted. Dephosphorization slag was used as the phosphorus raw material, with a typical composition by mass of CaO: 50%, SiO2: 18%, T.Fe: 10%, P2O5: 7% (P: 3%). Waste glass was used as the silicon raw material, with a typical composition by mass of SiO2: 80%, B2O5: 10%, Al2O3: 3%. Coke and pulverized coal were used as the carbonaceous materials, with the chemical compositions of the coke and pulverized coal being shown in Table 2. Iron scrap was used as the iron raw material, with an iron purity of 99% by mass and a bulk density of 3,500 kg / m 3 , with a maximum dimension of 0.4m.

[0068] The mixture of raw materials charged was 500 kg of iron scrap, 70 kg of coke, 85 kg of RDF, 600 kg of waste glass, and 3,850 kg of dephosphorized slag per ton of molten iron obtained. The oxygen blown in as a combustion supporting gas from the primary and secondary tuyeres was 362 Nm3 per ton of molten iron obtained. 3 Pulverized coal was supplied together with oxygen from the primary tuyeres at a rate of 250 kg per ton of molten iron obtained. Under these conditions, the iron scraps were heated for about 108 minutes for each charge, producing about 1.07 t of molten iron at about 1400°C and about 4.1 t of slag in the furnace. The molten iron was discharged from the tap hole and granulated with water to obtain phosphorus-containing iron. The chemical composition of the phosphorus-containing iron was, by mass%, 2% C and 10% P, with the remainder being Fe and impurities.

[0069] (Preparation of solids) The raw material used was the artificial phosphate rock produced above. First, the artificial phosphate rock was ground and sieved to 355 μm or less. Next, 100 mL of 0.5 M nitric acid was prepared in a 200 mL Erlenmeyer flask, and 1.00 g of the sieved artificial phosphate rock was added to extract the phosphorus compounds. The extraction was carried out at a temperature of 293 K and stirring at 130 rpm for 0.2 hours. After the phosphorus compounds were extracted, filtration was performed to separate the eluate (100 mL) from the residue.

[0070] Next, ammonia water was added to the eluate to adjust the pH to 4, thereby forming a precipitate. The precipitate was formed by stirring at 200 rpm for 30 minutes at room temperature, and then leaving it to stand for 30 minutes. The precipitate and the filtrate were then separated by filtration, and dried at 353 K for 24 hours to obtain a precipitate (solid matter) containing phosphorus compounds.

[0071] (Solid matter dissolution treatment) The solid produced by the above procedure was dissolved in 100 mL of 0.5 M nitric acid. Dissolution was performed by stirring at 200 rpm at room temperature for 1 hour. After stirring, the acid eluate (phosphorus compound solution) was separated from the residue by filtration.

[0072] (cation exchange treatment) The eluate obtained by the dissolution treatment was further treated with a cation exchange resin. A burette was filled with glass wool and 5.00 g of a strong acid cation exchange resin (PK216LH, manufactured by Mitsubishi Chemical Corporation), and the eluate was introduced into the burette at a flow rate of 2.5 mL / min using a pump. The solution was collected 2 minutes after the introduction.

[0073] As a result of the cation exchange process, high-purity orthophosphoric acid (H3PO4) was obtained. When artificial phosphate rock was used as the raw material, a high phosphorus purity was confirmed, especially in the stage of treating the artificial phosphate rock with acid, and the purification of phosphorus compounds could be carried out more efficiently. [Industrial Applicability]

[0074] The method for producing a phosphorus compound according to the present invention can efficiently produce a phosphorus compound with high purity, and is therefore useful for obtaining phosphorus compounds for use in various fields such as agriculture, food, high technology, and pharmaceutical and chemical fields.

Claims

1. A method for producing a phosphoric acid compound from a solid material containing phosphorus and silicon elements and having a calcium element content of 20 mass% or less, comprising the steps of: A dissolution step of dissolving the solid material with an acid to obtain a phosphoric acid compound solution, The method for producing a phosphoric acid compound, characterized in that the solid is obtained by the following steps: (i-A) Step of extracting phosphate compounds from dephosphorization slag using acid (ii) A step of adjusting the pH of the obtained phosphoric acid compound extract by adding an alkali to obtain a precipitate as a solid.

2. A method for producing a phosphoric acid compound from a solid material containing phosphorus and silicon elements and having a calcium element content of 20 mass% or less, comprising the steps of: A dissolution step of dissolving the solid material with an acid to obtain a phosphoric acid compound solution, The method for producing a phosphoric acid compound, characterized in that the solid is obtained by the following steps: (i-B) A step of charging raw materials containing phosphorus and iron elements and auxiliary materials containing silicon elements into a melting furnace, reducing them, concentrating phosphorus as phosphorus elements, and dissolving the artificial phosphate rock obtained in acid to extract a phosphoric acid compound. (ii) A step of adjusting the pH of the obtained phosphoric acid compound extract by adding an alkali to obtain a precipitate as a solid.

3. 3. The method for producing a phosphoric acid compound according to claim 1 or 2, wherein the acid used in the dissolution treatment step and / or the acid used in the step (i) is nitric acid or hydrochloric acid.

4. The method for producing a phosphoric acid compound according to any one of claims 1 to 3, further comprising a cation exchange step of treating the obtained phosphoric acid compound solution with a cation exchange resin.

5. A method for producing amorphous silica from a solid material containing phosphorus and silicon elements and having a calcium content of 20 mass% or less, comprising the steps of: The solid material is treated with an acid, and the supernatant is removed to obtain amorphous silica as a solid. and an acid treatment step to obtain A method for producing amorphous silica, characterized in that the solid is obtained by the following steps: (i-A) Step of extracting phosphate compounds from dephosphorization slag using acid (ii) A step of adjusting the pH of the obtained phosphoric acid compound extract by adding an alkali to obtain a precipitate as a solid.

6. A method for producing amorphous silica from a solid material containing phosphorus and silicon elements and having a calcium content of 20 mass% or less, comprising the steps of: The solid material is treated with an acid, and the supernatant is removed to obtain amorphous silica as a solid. and an acid treatment step to obtain A method for producing amorphous silica, characterized in that the solid is obtained by the following steps: (i-B) A step of charging raw materials containing phosphorus and iron elements and auxiliary materials containing silicon elements into a melting furnace, reducing them, concentrating phosphorus as phosphorus elements, and dissolving the artificial phosphate rock obtained in acid to extract a phosphoric acid compound. (ii) A step of adjusting the pH of the obtained phosphoric acid compound extract by adding an alkali to obtain a precipitate as a solid.

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