JP2020163374A - Sulfur-containing compound and production method thereof, cement composition and production method thereof, and production device of sulfur-containing compound - Google Patents

Abstract

To provide a production method of a sulfur-containing compound allowing low-cost production of a sulfur-containing compound effective for reducing elution of hexavalent chromium.SOLUTION: A production method of a sulfur-containing compound has: a heating step for heating a sulfur-containing wastes to obtain sulfurous acid gas; and a reaction step of reacting sulfurous acid gas with an alkali source including at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds to obtain a sulfur-containing compound including sulfite.SELECTED DRAWING: None

Description

The present disclosure relates to a sulfur-containing compound and a method for producing the same, a cement composition and a method for producing the same, and an apparatus for producing the sulfur-containing compound.

Cement clinker is produced using limestone, clay, silica stone, iron oxide and the like as main raw materials. In the production of cement clinker, in addition to these main raw materials, various industrial by-products and industrial wastes are effectively used as raw materials and fuels. However, depending on the selection of raw materials, heavy metals such as cadmium, chromium, and lead derived from various raw materials may be mixed in the cement clinker in a very small amount.

Among heavy metals, hexavalent chromium, unlike other heavy metals, present in the form of a stable oxo anions such chromate ions (CrO 4 ^_2-), even at high pH conditions hardly soluble Does not form hydroxides. Therefore, when the ground is solidified using a cement-based ground improvement material, there is a concern that hexavalent chromium may elute depending on the conditions of use such as soil quality, amount of addition, and strength development. Many studies have been conducted on methods for suppressing the elution of hexavalent chromium from solidified soil using a cement-based solidifying material. For example, Patent Documents 1 to 3 propose a method of reducing the elution of hexavalent chromium from solidified soil by adding a reducing agent such as sulfite to cement (see Patent Documents 1 to 3). Further, it has been proposed to produce a sulfur-based compound such as calcium sulfite by reacting sulfurous acid gas with slaked lime or sodium sulfite with slaked lime in a liquid phase (see Patent Document 4).

JP-A-2010-222795 Japanese Unexamined Patent Publication No. 2016-121047 Japanese Unexamined Patent Publication No. 2016-216548 JP-A-7-215718A

Since commercially available sulfites such as calcium sulfite are expensive, the manufacturing cost of cement compositions and cement-based ground improvement materials increases when commercially available products are used. Therefore, the present disclosure provides a method for producing a sulfur-containing compound and a cement composition, which can produce a sulfur-containing compound and a cement composition effective for reducing the elution of hexavalent chromium at a low production cost. Further, a sulfur-containing compound and a cement composition which can be produced at a low production cost and are effective in reducing elution of hexavalent chromium are provided. Further, the present invention provides an apparatus for producing a sulfur-containing compound capable of producing a sulfur-containing compound effective for reducing the elution of hexavalent chromium at a low production cost.

The method for producing a cement composition according to one aspect of the present disclosure is selected from a heating step of heating sulfur-containing waste to obtain sulfurous acid gas, a group consisting of sulfurous acid gas, an alkali metal compound and an alkaline earth metal compound. It has a reaction step of reacting with an alkali source containing at least one kind to obtain a sulfur-containing compound containing a sulfite.

In this production method, a sulfur-containing compound is produced using sulfur-containing waste. Since this sulfur-containing compound contains sulfites, it is effective in suppressing the elution of hexavalent chromium. Therefore, a sulfur-containing compound effective for suppressing the elution of hexavalent chromium can be produced at a low production cost. Examples of the sulfur-containing waste include waste gypsum board, desulfurized sludge, slag, and other sulfur-containing waste and by-products such as gypsum and sulfide.

In the heating step, it is preferable to heat a carbon source containing at least one selected from the group consisting of paper, waste plastic, carbon fiber, biomass, coal and petroleum together with sulfur-containing waste. As a result, the carbon source reacts with oxygen contained in the sulfur-containing waste, promotes the decomposition of the sulfur-containing waste, and can efficiently generate sulfurous acid gas and hydrogen sulfide at a low temperature.

In the heating step, it is preferable to heat 10 to 1000 parts by mass of the carbon source together with 100 parts by mass of the sulfur-containing waste. Thereby, a gas containing sulfurous acid gas at a suitable concentration can be smoothly obtained.

It is preferable to have a pulverization step of pulverizing the sulfur-containing waste before the heating step, and the sulfur-containing waste contains at least one selected from the group consisting of sulfates, sulfides and sulfur. Thereby, a gas containing sulfurous acid gas at a suitable concentration can be smoothly obtained.

In the heating step, it is preferable to obtain a gas containing sulfurous acid gas at a concentration of 100 ppm to 5%, and in the reaction step, it is preferable to bring the gas into contact with an alkaline source. Thereby, the sulfur-containing compound can be smoothly produced.

The sulfite preferably contains at least one selected from the group consisting of calcium sulfite, sodium sulfite, magnesium sulfite, calcium sulfite, sodium bisulfite and magnesium sulfite. This makes it possible to produce a sulfur-containing compound that is more effective in suppressing the elution of hexavalent chromium.

In the heating step, it is preferable to heat and react the sulfur-containing waste and the sulfur-containing sulfur source different from the sulfur-containing waste. As a result, sulfur can react with oxygen contained in sulfur-containing waste to efficiently generate sulfite gas. It should be noted that a sulfur combustion step of burning a sulfur source containing sulfur may be provided before the heating step. In this case, the high-temperature combustion gas from the sulfur combustion step may be used as a heat source for decomposing the sulfur-containing waste in the heating step.

In the heating step, it is preferable to heat and react the silicon source containing the silicate compound and / or the aluminum source containing aluminum oxide together with the sulfur-containing waste. As a result, calcium contained in gypsum or the like contained in the sulfur-containing waste in the heating step produces a calcium silicate compound or calcium aluminate, and the decomposition of the sulfur-containing waste is promoted. By heating under such conditions, sulfurous acid gas can be generated in a low temperature region, and the production cost of the sulfur-containing compound can be further reduced.

In the heating step, it is preferable to obtain an ash containing sulfide. The ash containing sulfide can be suitably used as a reducing agent in, for example, cement production, together with a sulfurous acid compound produced by reacting sulfurous acid gas contained in the gas phase. In the heating step, sulfide can be generated in the ash by reducing the oxygen concentration in the heating gas as much as possible.

When the alkali source contains an alkali metal compound, the alkali metal compound is at least selected from the group consisting of sodium carbonate, sodium hydrogen carbonate, sodium hydroxide, sodium citrate, sodium formate, potassium carbonate, potassium hydrogen carbonate and potassium hydroxide. It is preferable to include one kind. When the alkaline source contains an alkaline earth metal compound, the alkaline earth metal compound preferably contains at least one selected from the group consisting of calcium carbonate, calcium hydrogen carbonate, slaked lime, calcium oxide, and calcium chloride. As a result, the sulfur-containing compound can be produced at a lower cost.

As an alkali source, fine particle powder containing calcium carbonate as a main component generated when the raw material of cement clinker is crushed, dust particles of a calcium compound extracted from a chlorine bypass part, water-washed dust particles obtained by washing the dust particles with water, and cement. It is preferable to use at least one selected from the group consisting of sludge containing at least one of cement hydrate and ash generated in the heating step. By using the product (by-product) in the cement clinker production facility in the reaction step, it becomes possible to produce a sulfur-based compound at a lower cost.

The above-mentioned production method includes a slurry preparation step of preparing a raw material slurry containing an alkali source and water, and it is preferable to use the raw material slurry as an alkali source in the reaction step. By using the raw material slurry, the reaction between the sulfur dioxide gas and the alkaline source can be efficiently promoted. Further, the sulfur-containing compound obtained in the reaction step can be made into a slurry and can be suitably used for producing a cement composition.

The ratio of the solid content in the raw material slurry is preferably 0.1 to 90% by mass. As a result, the handleability of the raw material slurry can be maintained well.

It is preferable to have an introduction step of blowing the exhaust gas generated in the reaction step into the kiln for producing the cement clinker or the magnesia clinker. Since the exhaust gas from the reaction process may contain a trace amount of sulfur dioxide gas and hydrogen sulfide, it is possible to effectively utilize the resources by using these as raw materials for cement clinker. The blow to the kiln may be put into the kiln secondary air, or may be blown into the cyclone preheater.

The apparatus for producing a sulfur-containing compound according to one aspect of the present invention is selected from the group consisting of a heating unit for heating sulfur-containing waste to obtain sulfurous acid gas, sulfurous acid gas, an alkali metal compound and an alkaline earth metal compound. It is provided with a reaction section for reacting with an alkali source containing at least one kind to obtain a sulfur-containing compound containing a sulfite.

In this production apparatus, a sulfur-containing compound is produced using sulfur-containing waste. Since this sulfur-containing compound contains sulfites, it is effective in suppressing the elution of hexavalent chromium. Therefore, a sulfur-containing compound effective for suppressing the elution of hexavalent chromium can be produced at a low production cost.

It is preferable to use a kiln for producing cement clinker or magnesia clinker as the heating part. By using a kiln as a heating part of a device for producing a sulfur-containing compound, a sulfur-containing compound containing a sulfite can be produced at a low production cost.

The sulfur-containing compound according to one aspect of the present disclosure can be obtained by any of the above-mentioned production methods. Since sulfur-containing waste is used in this production method, a sulfur-containing compound containing a sulfite, which is effective in suppressing the elution of hexavalent chromium, can be produced at a low production cost.

The method for producing a cement composition according to one aspect of the present disclosure includes a step of obtaining a cement composition using a sulfur-containing compound obtained by any of the above-mentioned production methods and a cement clinker. According to this production method, a cement composition effective for suppressing the elution of hexavalent chromium can be produced at a low production cost.

The method for producing a cement composition according to another aspect of the present disclosure includes one or both of a sulfur-containing compound obtained by the production method described in any of the above and an ash obtained in the heating step, a cement clinker, and gypsum. And have a step of obtaining a cement composition using. According to this production method, a cement composition effective for suppressing the elution of hexavalent chromium can be produced at a low production cost.

The cement composition according to one aspect of the present disclosure can be obtained by either of the above-mentioned production methods. This cement composition is effective in suppressing the elution of hexavalent chromium, and since it is produced by using the above-mentioned sulfur-containing compound, it can be produced at a low production cost.

According to the present disclosure, it is possible to provide a method for producing a sulfur-containing compound and a cement composition, which can produce a sulfur-containing compound and a cement composition effective for reducing the elution of hexavalent chromium at a low production cost. Further, it is possible to provide a sulfur-containing compound and a cement composition which can be produced at a low production cost and are effective in reducing the elution of hexavalent chromium. Further, it is possible to provide an apparatus for producing a sulfur-containing compound capable of producing a sulfur-containing compound effective for reducing the elution of hexavalent chromium at a low production cost.

FIG. 1 is a diagram showing the results of thermodynamic equilibrium calculation. FIG. 1A is the result of thermodynamic equilibrium calculation in the case of 1 mol of gypsum. FIG. 1B shows the result of thermodynamic equilibrium calculation when 0.4 mol of carbon was added to 1 mol of gypsum. FIG. 1C shows the result of thermodynamic equilibrium calculation when 0.8 mol of carbon was added to 1 mol of gypsum. It is a figure which shows the result of thermodynamic equilibrium calculation. FIG. 2A shows the result of thermodynamic equilibrium calculation when 0.4 mol of sulfur was added to 1 mol of gypsum. FIG. 2B shows the result of thermodynamic equilibrium calculation when 0.8 mol of sulfur was added to 1 mol of gypsum. FIG. 2C shows the results of thermodynamic equilibrium calculation when 0.4 mol of sulfur and 0.4 mol of carbon were added to 1 mol of gypsum. FIG. 3 shows the results of thermodynamic equilibrium calculation when 0.4 mol of sulfur, 0.4 mol of carbon, 0.4 mol of silicon and 0.4 mol of aluminum were added to 1 mol of gypsum. FIG. 4 is a diagram showing an example of an apparatus for producing a sulfur-containing compound and a cement composition. FIG. 5 is a diagram showing another embodiment of an apparatus for producing a sulfur-containing compound and a cement composition. FIG. 6 is a diagram showing still another embodiment of an apparatus for producing a sulfur-containing compound and a cement composition. FIG. 7 is a diagram showing still another embodiment of an apparatus for producing a sulfur-containing compound and a cement composition. FIG. 8 is a diagram showing still another embodiment of an apparatus for producing a sulfur-containing compound and a cement composition.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings in some cases. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and duplicate description may be omitted in some cases.

The method for producing a sulfur-containing compound according to an embodiment of the present disclosure is selected from a heating step of heating sulfur-containing waste to obtain sulfurous acid gas, a group consisting of sulfurous acid gas, an alkali metal compound and an alkaline earth metal compound. It has a reaction step of reacting with an alkali source containing at least one of these to obtain a sulfur-containing compound containing a sulfite.

Sulfur-containing wastes include those containing at least one selected from waste gypsum board, waste tires, desulfurized slag, gypsum, and cokes. In addition, in this embodiment, the waste gypsum board may contain the paper component adhering to the surface of the gypsum board.

In the heating step, the sulfur-containing waste is heated to 500 to 1500 ° C., preferably 700 to 1400 ° C., more preferably 700 to 1200 ° C., still more preferably 700 to 1000 ° C. to generate sulfurous acid gas. The heating atmosphere may be a reducing atmosphere having an oxygen concentration lower than that of the atmosphere. The oxygen concentration in the heated atmosphere is, for example, 18% by volume or less, preferably 15% by volume or less, more preferably 10% by volume or less, and most preferably 5% by volume or less. By heating under such conditions, sulfurous acid gas and hydrogen sulfide can be efficiently generated. The sulfur dioxide gas obtained in the heating step may be obtained in a state of being contained in the exhaust gas containing other components.

The concentration of sulfur dioxide gas obtained in the heating step is preferably 100 ppm to 10%, more preferably 500 ppm to 5%, still more preferably 1000 ppm to 2%. If the concentration of sulfurous acid gas is less than 100 ppm, the production amount of the sulfur-containing compound tends to decrease and the production cost tends to increase. On the other hand, when the concentration of sulfur dioxide gas exceeds 5%, the reaction efficiency between the sulfur dioxide gas and the alkaline source tends to decrease.

When the sulfur-containing waste contains gypsum and carbon, the reaction represented by the following reaction formula (1) proceeds in the heating step, for example. In the heating step, a carbon source may be added to the sulfur-containing compound for heating in order to promote the generation of SO ₂ . Examples of carbon sources include those containing at least one selected from the group consisting of paper, waste plastics, carbon fibers, biomass, coal and petroleum.
2CaSO ₄ + C → 2CaO + 2SO ₂ + CO ₂ (1)

FIG. 1 is a diagram showing the results of thermodynamic equilibrium calculation. FIG. 1A is the result of thermodynamic equilibrium calculation in the case of 1 mol of gypsum. FIG. 1B shows the result of thermodynamic equilibrium calculation when 0.4 mol of carbon was added to 1 mol of gypsum. FIG. 1C shows the result of thermodynamic equilibrium calculation when 0.8 mol of carbon was added to 1 mol of gypsum. As shown in FIG. 1, by heating gypsum with carbon and by increasing the ratio of carbon to gypsum, the decomposition of gypsum is promoted, the amount of sulfur dioxide gas generated is increased, or the heating temperature is reduced. can do. Therefore, if the sulfur-containing waste contains gypsum and a carbon source such as paper, such as waste gypsum board, sulfurous acid gas is smoothly generated. Further, when the sulfur-containing waste does not contain a carbon source or the content of the carbon source is low, it is preferable to heat the sulfur-containing waste together with the carbon source.

In the heating step, the carbon source is blended in a proportion of preferably 10 to 1000 parts by mass, more preferably 20 to 500 parts by mass, and further preferably 80 to 200 parts by mass with respect to 100 parts by mass of the sulfur-containing waste. May be heated. If the ratio of the carbon source is less than 10 parts by mass, the sulfur-containing waste tends to be sufficiently difficult to react. On the other hand, when the ratio of the carbon source exceeds 1000 parts by mass, the efficiency of generating sulfurous acid gas tends to decrease due to the combustion of excess carbon.

In the heating step, it is preferable to heat the sulfur-containing waste together with a sulfur-containing sulfur source. When gypsum is heated together with sulfur, the reaction represented by the following reaction formula (2) proceeds in the heating step, for example.
2CaSO ₄ + 2S → 2CaO + 3SO ₂ (2)

Further, sulfur may be burned in another furnace to generate a high-temperature gas containing a high concentration of SO ₂ and a low oxygen concentration, and the gas temperature may be used to cause decomposition of gypsum. The temperature of this gas is, for example, 800 to 1500 ° C, preferably 1000 to 1500 ° C, more preferably 1200 to 1500 ° C.

FIG. 2 is a diagram showing the results of thermodynamic equilibrium calculation. FIG. 2A shows the result of thermodynamic equilibrium calculation when 0.4 mol of sulfur was added to 1 mol of gypsum. FIG. 2B shows the result of thermodynamic equilibrium calculation when 0.8 mol of sulfur was added to 1 mol of gypsum. As shown in FIGS. 1 (A), 2 (A) and 2 (B), the decomposition of gypsum is promoted by heating sulfur with gypsum and by increasing the ratio of sulfur to gypsum. The amount of sulfur dioxide gas generated can be increased or the heating temperature can be reduced.

FIG. 2C shows the results of thermodynamic equilibrium calculation when 0.4 mol of sulfur and 0.4 mol of carbon were added to 1 mol of gypsum. As shown in FIG. 2C, by heating both sulfur and carbon together with gypsum, the decomposition of gypsum is further promoted, and the amount of sulfur dioxide gas generated can be further increased.

In the heating step, it is preferable to heat the sulfur-containing waste together with the carbon source and the silicon source. When calcium sulfate is heated together with a carbon source and a silicon source (silicate compound), the reaction represented by the following reaction formula (3) proceeds in the heating step, for example. Further, in addition to the silicon source, an aluminum source (aluminum oxide or the like) may be heated together. As the silicon source and the aluminum source, wastes and by-products containing mullite, silicate glass, aluminosilicate glass and the like may be used. For example, coal ash, municipal waste incineration ash, construction-generated soil, biomass ash, etc. can be used.
2CaSO ₄ + C + silicon source (silicate compound) →
Calcium silicate-based oxide + 2SO ₂ + CO ₂ (3)

The ash produced in the heating step preferably contains sulfide. The ash containing this sulfide can be put into a pulverization step for producing a cement composition and pulverized together with cement clinker or gypsum to produce a cement composition capable of reducing the amount of hexavalent chromium eluted. it can. The ash containing sulfide may be mixed with the slurry containing sulfite and added in the pulverization step.

The content of sulfur in ash contained as sulfide (sulfur content in sulfide form) is determined by analyzing the diffraction pattern obtained by powder X-ray diffraction measurement by the Rietbelt method and quantifying the amount of sulfur contained. From the value, it can be calculated by the following formula. When a plurality of types of sulfides are contained, the sulfur content of each sulfide form can be determined and then added up.
Sulfide content / Molecular weight of sulfide x Molecular weight of sulfur = Sulfur content in sulfide form

The sulfur content in the sulfide form may be determined in accordance with the method for quantifying sulfur sulfide in JIS R 5202 “Chemical analysis method for cement”.

The content of sulfur in the sulfide form in the ash is preferably 0.1 to 44% by mass, more preferably 1-42% by mass, and even more preferably 5 to 40% by mass. If the sulfur content in the sulfide form in the ash is less than 0.1% by mass, it tends to be difficult to sufficiently reduce the elution of hexavalent chromium. On the other hand, if the content of sulfur in the sulfide form in the ash exceeds 44% by mass, the production efficiency of sulfite gas deteriorates, and the production cost of the sulfur-containing compound tends to increase.

FIG. 3 shows the results of thermodynamic equilibrium calculation when 0.4 mol of sulfur, 0.4 mol of carbon, 0.4 mol of silicon and 0.4 mol of aluminum were added to 1 mol of gypsum. As shown in FIG. 3, by heating sulfur, carbon, silicon and aluminum together with gypsum, the decomposition of gypsum is further promoted, the amount of sulfur dioxide gas generated is further increased, or the heating temperature is reduced. Can be done.

1 to 3 show the results of thermodynamic equilibrium calculation when the sulfur-containing waste contains gypsum, but the present invention is not limited to this. That is, it is not essential that the sulfur-containing waste contains gypsum, and sulfur-containing waste that generates sulfurous acid gas in the heating step can be appropriately used.

In the reaction step, for example, as shown in the reaction formula (4), the sulfurous acid gas obtained in the heating step is reacted with an alkali source to obtain a sulfur-containing compound containing a sulfite. In the formula (4), M represents any of Na ₂ , K ₂ , Ca or Mg.
MO + SO ₂ → MSO ₃ (4)

The alkali source may contain either an alkali metal compound or an alkaline earth metal compound, or may contain both. The alkali metal compound used as an alkali source contains at least one selected from the group consisting of sodium carbonate, sodium hydrogen carbonate, sodium hydroxide, sodium citrate, sodium formate, potassium carbonate, potassium hydrogen carbonate and potassium hydroxide. Is preferable. This makes it possible to generate sulfites in a sufficiently high yield in the reaction step.

The alkaline earth metal compound used as an alkali source preferably contains at least one selected from the group consisting of calcium carbonate, calcium hydrogen carbonate, slaked lime, calcium oxide, and calcium chloride. This makes it possible to generate sulfites in a sufficiently high yield in the reaction step.

Further, as an alkali source, fine particle powder containing calcium carbonate as a main component generated when the raw material of cement clinker is crushed, dust particles of a calcium compound extracted from a chlorine bypass portion, and water-washed dust particles obtained by washing the dust particles with water. , Cement and sludge containing at least one of cement hydrates, and at least one selected from the group consisting of ash generated in the heating step. As a result, sulfites can be produced at a lower cost.

The sulfur-containing compound obtained in the reaction step contains a sulfite (sulfite compound). Sulfites include at least one selected from the group consisting of calcium sulfite (eg, hemihydrate), sodium sulfite, magnesium sulfite, calcium sulfite (Ca (HSO ₂ ) ₂ ), sodium bisulfite and magnesium sulfite. Is preferable. A double salt of calcium sulfite and calcium sulfate is also included in the above sulfites. As a result, a sulfur-containing compound that is more effective in suppressing the elution of hexavalent chromium can be produced. The sulfur-containing compound may contain a sulfide such as calcium sulfide. Such a sulfur-containing compound can be more preferably used as a reducing agent in, for example, cement production.

When the gas generated in the heating step contains hydrogen sulfide, in the reaction step, salts such as calcium sulfide, sodium sulfide, and magnesium sulfide are also produced in addition to sulfites. In this case, the sulfur-containing compound contains salts such as calcium sulfide, sodium sulfide, and magnesium sulfide in addition to sulfites.

The sulfite compound may be in the form of a slurry (hereinafter, referred to as “sulfur-containing compound slurry”). The content of the sulfite compound (anhydrous equivalent) in the sulfur-containing compound slurry is preferably 5% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, based on the total solid content. , Particularly preferably 70% by mass or more, and most preferably 90% by mass or more.

The sulfur-containing compound slurry may contain components other than the sulfite compound. Examples of such a component include calcium hydroxide, calcium carbonate, magnesium hydroxide, calcium sulfate and the like. It may contain at least one of these components. Calcium sulfate may contain any of dihydrate (dihydrate gypsum), hemihydrate (hemihydrate gypsum), and anhydrous (anhydrous gypsum).

The method for producing a sulfur-containing compound of the present embodiment preferably includes a raw material slurry preparation step of mixing the above-mentioned alkali source and water to prepare a raw material slurry. If this raw material slurry is used as an alkali source in the heating step, the reaction between the sulfur dioxide gas and the alkali source can proceed efficiently. The raw material slurry preferably contains a calcium compound. Further, it may contain an ash containing CaO obtained in the heating step. Examples of the calcium compound include calcium carbonate and lime (slaked lime and quick lime). As the calcium compound, those produced in the heating step can be used.

It is more preferable that the raw material slurry contains 10 to 98% by mass of the calcium compound as CaO with respect to the entire inorganic powder. The proportion of the solid content in the raw material slurry is preferably 0.1 to 90% by mass, more preferably 1 to 85% by mass, and 5 to 80% by mass from the viewpoint of improving handleability. It is more preferable to have.

The raw material slurry may be prepared by recovering the inorganic compound generated in the cement clinker manufacturing process. Examples of such an inorganic compound include fine particle powder containing CaCO ₃ as a main component generated when crushing a clinker raw material, dust particles containing CaO and / or Ca (OH) ₂ generated in a chlorine bypass portion, and the dust. Examples thereof include water-washed dust particles obtained by washing the particles with water. The raw material slurry may be prepared by blending sludge containing cement and / or cement hydrate. Examples of sludge include raw cons sludge obtained at a ready-mixed factory.

The sulfite compound does not have to be in the form of a slurry as described above. In a modified example, a powdery sulfurous acid compound may be obtained by spray-drying the raw material slurry by spraying it into sulfurous acid gas or an exhaust gas containing the raw material slurry in the reaction step. Further, in another modification, the reaction step may be carried out by contacting the components contained in the above-mentioned raw material slurry with sulfur dioxide gas as they are in the solid state (powder form) without performing the raw material slurry preparation step. In this case, the reaction step can be carried out using, for example, a fluidized layer containing an alkali source, a calcium compound, ash or the like as solid particles. In this case as well, a powdery sulfurous acid compound can be obtained.

It is preferable to have an introduction step of blowing the exhaust gas obtained in the reaction step into the kiln for producing the cement clinker or the magnesia clinker. As a result, a trace amount of sulfur-based gas contained in the exhaust gas can be effectively used as a raw material for clinker. In addition, the treatment cost of harmful exhaust gas can be reduced.

In the method for producing a sulfur-containing compound of the present embodiment, cement clinker may be produced as a heating step. Sulfur dioxide-containing compound slurry may be obtained by reacting sulfur dioxide gas contained in the exhaust gas generated during the production of cement clinker with the raw material slurry. The cement composition may be obtained by blending the sulfur-containing compound slurry with a cement clinker. In this case, the production method of the present embodiment also corresponds to the production method of the cement composition. According to this manufacturing method, it is possible to easily manufacture a cement composition capable of reducing the elution of hexavalent chromium without installing a large-scale new facility. The sulfur-containing compound slurry also contributes to desulfurization of exhaust gas, and since the sulfite is used as it is without drying, it is possible to simplify a series of processes of desulfurization and production of a cement composition. Further, since the sulfur-containing compound slurry can be used instead of water injection at the time of crushing the cement composition and the cement composition is in the form of a slurry, the mixture of the sulfite compound and the cement clinker is improved, and the manufacturing process of the cement composition is shortened. In addition to simplifying the equipment, there is an advantage that the production cost of a cement composition effective for reducing the elution of hexavalent chromium can be significantly reduced.

FIG. 4 is a diagram showing an embodiment of a manufacturing apparatus for manufacturing a sulfur-containing compound and a cement composition. The manufacturing apparatus 100 includes a heating unit 70, a raw material slurry preparation unit 34, and a reaction unit 30. In the heating unit 70, the heating step can be performed based on the above description. Exhaust gas containing sulfurous acid gas or sulfurous acid gas is generated in the heating unit 70 (in the figure, it is indicated as "SO ₂ " for convenience). The reaction unit 30 is, for example, a bubbling tank, and the reaction step can be performed based on the above description. The raw material slurry preparation unit 34 can perform the raw material slurry preparation step based on the above-mentioned contents.

The manufacturing apparatus 100 includes a slurry concentration adjusting unit 36, a compounding unit 51, and a cement mill 52 on the downstream side of the reaction unit 30. The sulfur-containing compound slurry (sulfur-containing compound) obtained in the reaction section 30 may be used in the production of a cement composition as a reducing agent, for example, as described below. At least a part of the exhaust gas discharged from the reaction unit 30 may be introduced into, for example, the heating unit 70 or another cement kiln. As a result, when the exhaust gas contains sulfite gas, the sulfite gas can be effectively utilized.

The slurry concentration adjusting unit 36 performs a slurry concentration adjusting step. The slurry concentration adjusting unit 36 adjusts the solid content concentration in the sulfur-containing compound slurry by drying, dehydrating or adding water. For example, the slurry concentration adjusting unit 36 may have a dehydrating unit and a drying unit. The solid content concentration of the sulfur-containing compound slurry is adjusted by blending the sulfur-containing compound slurry dehydrated in the dehydrated part, the solid content obtained by drying in the dried part, and the non-dehydrated sulfur-containing compound slurry. May be good. The solid content concentration in the sulfur-containing compound slurry after adjusting the slurry concentration may be 0.1 to 95% by mass. The proportion of the solid content in the sulfur-containing compound slurry is preferably 1 to 70% by mass, more preferably 3 to 50% by mass, and further preferably 5 to 40% by mass. Within such a range, the mixture of the sulfur-containing compound slurry and the cement composition can be sufficiently made uniform while maintaining a high level of handleability of the sulfur-containing compound slurry.

The content of sulfites (in terms of anhydride) in the sulfur-containing compound slurry with respect to the total solid content is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, still more preferable. Is 20% by mass or more. The sulfur-containing compound slurry thus obtained in the slurry concentration adjusting step may be obtained as a sulfur-containing compound containing a sulfite.

In the compounding section 51, a compounding step of blending the sulfur-containing compound slurry whose slurry concentration has been adjusted by the slurry concentration adjusting section 36 and the cement clinker is performed. When the obtained cement composition is 100 parts by mass, the cement clinker is used, and the sulfur-containing compound slurry is preferably 0.1 to 20 parts by mass in terms of anhydrous sulfate (or anhydrous calcium sulfite). It is preferably blended in an amount of 0.15 to 15 parts by mass, more preferably 0.2 to 10 parts by mass, and particularly preferably 0.25 to 5 parts by mass. Thereby, the compound can be smoothly pulverized while maintaining the content of sulfite in the obtained cement composition. When the sulfur-containing compound slurry contains a double salt of calcium sulfite and calcium sulfate, calcium sulfite in the double salt may be contained in the above-mentioned mass ratio.

In the compounding section 51, gypsum may be compounded if necessary. The gypsum to be blended may be in any form of dihydrate gypsum, semi-hydrated gypsum and anhydrous gypsum. Each form of gypsum may be blended alone or in combination of two or more. The order of blending the cement clinker, the sulfur-containing compound slurry and the gypsum is not particularly limited, and two of these may be blended first and then the remaining one may be blended, or three of them may be blended at the same time. May be good. The blending amount of gypsum may be about 3 to 10% by mass in terms of SO _{3 with} respect to the cement clinker. The gypsum may be prepared by oxidizing and dehydrating a part of the sulfur-containing compound slurry. The mixing ratio of gypsum to cement clinker 100 parts by weight may be about 1.5 to 20 parts by weight converted to SO _3.

In the cement mill 52, a pulverization step of pulverizing a cement clinker, a sulfur-containing compound slurry and, if necessary, a compound containing gypsum is performed. The cement mill 52 may be a ball mill or a vertical mill. In this way, the cement composition is obtained. That is, the manufacturing apparatus 100 also corresponds to a cement composition manufacturing apparatus that performs a method for producing a cement composition.

Since the cement composition thus obtained contains a sulfur-containing compound containing a sulfite, the elution amount of hexavalent chromium can be reduced. Moreover, since the sulfur-containing compound is derived from sulfur-containing waste, the cement composition can be produced at a low production cost. The compounding portion 51 and the cement mill 52 may be integrated to perform compounding and pulverization at the same time. In this case, a cement clinker, a sulfur-containing compound slurry, gypsum, a pulverizing aid, and the like are introduced into the cement mill 52 and mixed while being pulverized to produce a cement composition.

The cement composition produced in this manner can be made into Portland cement specified in JIS R 5210 "Portland cement". Examples of such Portland cement include ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, and low heat Portland cement. Further, at least one selected from blast furnace slag, fly ash and siliceous material may be added to these Portland cements to make mixed cements.

Since the cement composition contains sulfites, the content of hexavalent chromium in the cement composition can be reduced. The content of sulfite in the cement composition is, for example, preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 1 to 5% by mass.

The brain specific surface area of the cement composition is preferably 2500 to 6000 cm ² / g, and more preferably 3000 to 5000 cm ² / g. When the brain specific surface area is 2500 cm ² / g or more, it becomes easy to achieve excellent strength development. On the other hand, when the brain specific surface area is 6000 cm ² / g or less, it is easy to control the viscosity when used as a concrete or solidifying material slurry within a suitable range.

The form of gypsum contained in the cement composition is preferably dihydrate gypsum or anhydrous gypsum (type II). The proportion of hemihydrate gypsum in the gypsum contained in the cement composition may be 98% by mass or less, preferably 0.1 to 95% by mass, based on the total amount of dihydrate gypsum and anhydrous gypsum. It is more preferably 5 to 85% by mass, and even more preferably 10 to 30% by mass.

When ash containing a calcium compound (for example, CaO) is generated in the heating unit 70, it may be introduced into the raw material slurry preparation unit 34. Thereby, the calcium compound and the ash can be effectively utilized. When ash containing sulfide (for example, CaS) is generated in the heating unit 70, it may be added to the cement composition in the compounding unit 51, for example. Thereby, a cement composition capable of further reducing the elution of hexavalent chromium can be obtained.

FIG. 5 is a diagram showing another embodiment of an apparatus for producing a sulfur-containing compound and a cement composition. The manufacturing apparatus 101 of FIG. 5 is different from the manufacturing apparatus 100 of FIG. 4 in that the reaction unit 30A obtains a powdery sulfur-containing compound by spray drying and does not include the slurry concentration adjusting unit 36. Other configurations of the manufacturing apparatus 101 are the same as those of the manufacturing apparatus 100 of FIG.

In the reaction unit 30A, the raw material slurry prepared by the raw material slurry preparation unit 34 is sprayed into sulfurous acid gas and dried. As a result, a particulate sulfite compound is obtained. The sulfite compound obtained in the reaction section 30A is introduced into the compounding section 51 and blended with cement clinker and, if necessary, gypsum. After blending, a cement composition is produced by a pulverization step in the cement mill 52.

FIG. 6 is a diagram showing still another embodiment of an apparatus for producing a sulfur-containing compound and a cement composition. In the manufacturing apparatus 102 of FIG. 6, the reaction unit 30B is a fluidized bed, the alkali source, CaO, and ash remain solid and come into contact with sulfurous acid gas, and the raw material slurry preparation unit 34 is not provided. It is different from the manufacturing apparatus 101. Other configurations of the manufacturing apparatus 102 are the same as those of the manufacturing apparatus 101 of FIG.

With the production apparatus 102, a sulfur-containing compound containing a sulfite can be obtained in the form of powder. When calcium compounds (for example, CaO) and ash are generated in the heating unit 70, these may be introduced into the reaction unit 30B. Thereby, the calcium compound and the ash can be effectively utilized. The alkaline source may also be introduced directly into the reaction section 30B in the form of powder.

FIG. 7 is a diagram showing still another embodiment of an apparatus for producing a sulfur-containing compound and a cement composition. The manufacturing apparatus 104 includes two heating units 70 and 71, which perform heating steps, respectively. The heating unit 71 is a cement clinker firing unit. The heating unit 70 may be another cement clinker firing unit, or may be a heating unit different from the cement clinker firing unit. The heating step is performed in the heating unit 70 and the heating unit 71.

The manufacturing apparatus 104 includes a cement kiln section 10 for producing cement clinker by firing sulfur-containing raw materials and clinker raw materials, a bypass section 12 for extracting exhaust gas, and a heating section 71 including a preheater section 16 having one or more cyclones. , The desulfurization unit 60, which absorbs the sulfur dioxide gas contained in the exhaust gas from the heating unit 71 into the raw material slurry to obtain a sulfur-containing compound slurry containing calcium sulfite, and the compound containing the cement clinker and the sulfur-containing compound slurry are pulverized. A crushing section 50 for obtaining a cement composition is provided.

The preheater section 16 brings the raw material into contact with the exhaust gas from the cement kiln section 10 to preheat the raw material. The bypass section 12 extracts exhaust gas containing sulfurous acid gas from between the kiln bottom 10a of the cement kiln section 10 and the bottom cyclone (the cyclone at the bottom) or the calcining furnace (not shown) of the preheater section 16. The bypass portion 12 may be a chlorine bypass portion. The cement clinker produced in the cement kiln section 10 is cooled to 40 to 220 ° C. in the cooling section 11 and introduced into the silo 18.

The desulfurization unit 60 cools the exhaust gas extracted from the bypass unit 12 and the exhaust gas extracted from the kiln tail 10a to, for example, 400 ° C. or lower, preferably 100 to 200 ° C. to generate dust particles containing a chlorine compound that aggregates. Sulfurous acid compound by contacting the cooling unit 17 to remove at least a part of the dust particles contained in the exhaust gas to obtain the exhaust gas containing sulfurous acid gas, and the raw material slurry containing the exhaust gas and the calcium compound. A reaction unit 30 for obtaining a sulfur-containing compound slurry containing calcium sulfite and a raw material slurry preparation unit 34 for preparing the raw material slurry are provided. The reaction step and the raw material slurry preparation step are performed in the reaction unit 30 and the raw material slurry preparation unit 34.

In the cement kiln portion 10, coal, petroleum coke, and the like are burned and the raw materials react to generate exhaust gas containing sulfurous acid gas. The gas extracted from the bleeding pipe forming the bypass portion 12 is recovered as exhaust gas between the kiln tail 10a of the cement kiln portion 10 and the preheater portion 16. The concentration of sulfur dioxide gas in the exhaust gas from the bypass portion 12 may be, for example, about 100 to 5000 ppm on a volume basis (standard state). The concentration of sulfur dioxide gas in the present disclosure is a volume-based (standard state) concentration unless otherwise specified.

The exhaust gas may be extracted from the kiln bottom 10a. The temperature of the exhaust gas extracted from the kiln tail 10a is, for example, 700 to 1200 ° C., and the concentration of sulfur dioxide gas may be 500 to 10000 ppm. The exhaust gas extracted from the kiln tail 10a and the exhaust gas from the bypass unit 12 are merged or individually introduced into the cooling unit 17 and cooled to, for example, about 100 to 200 ° C. (cooling step). The cooling in the cooling unit 17 may be performed by mixing the exhaust gas with outside air (air) or the like, or may be performed by a cooler using heat with cooling water or air or the like.

By cooling the exhaust gas, volatile chlorine compounds and the like aggregate on the surface of the dust particles originally contained in the exhaust gas. At least a part of such dust particles is removed by the dust collecting unit 19 (dust collecting step). The dust collector 19 has, for example, a bug filter. If the exhaust gas may contain dust particles, the exhaust gas may bypass the dust collecting unit 19 and be introduced directly into the reaction unit 30.

The dust particles collected by the dust collecting unit 19 are washed with water by the water washing unit 31 to reduce the salt content. The water-washed dust particles whose salt content is reduced in the water-washed portion 31 contain, for example, CaO and / or Ca (OH) ₂ . These water-washed dust particles are introduced into the raw material slurry preparation unit 34 and are effectively utilized not only for desulfurization of exhaust gas but also as a raw material for calcium sulfite. The dust particles collected by the dust collecting unit 19 may be directly introduced into the raw material slurry preparing unit 34 without being washed with water.

The exhaust gas from which at least a part of the dust particles has been removed in the dust collecting unit 19 is introduced into the reaction unit 30. In the reaction section 30, the raw material slurry and the exhaust gas containing sulfurous acid gas are brought into contact with each other. As a result, the sulfurous acid gas is incorporated into the raw material slurry to obtain a sulfur-containing compound slurry. In addition, it is possible to effectively utilize sulfur dioxide gas whose release into the atmosphere is restricted. In this way, the reaction unit 30 also functions as a flue gas desulfurization unit. The means of contacting the raw material slurry and the exhaust gas is not limited to bubbling, and a method of spraying the raw material slurry (spray drying) may be used.

Sulfurous acid gas from the heating unit 70 or an exhaust gas containing the sulfur dioxide gas from the heating unit 70 is also introduced into the reaction unit 30. The sulfite gas (exhaust gas) from the heating unit 70 and the exhaust gas from the dust collecting unit 19 may be introduced into the reaction unit 30 after merging, or may be individually introduced into the reaction unit 30. It is not essential to include the heating unit 70, and the sulfur-containing compound slurry and the cement composition may be produced using only the sulfur dioxide gas generated by the heating unit 71.

Air may be introduced into the reaction section 30. Thereby, a part of calcium sulfite may be oxidized to obtain a dihydrate of calcium sulfate. Thereby, a sulfur-containing compound slurry containing calcium sulfite and a dihydrate of calcium sulfate can be obtained. The sulfur-containing compound slurry thus obtained may be used for producing a cement composition, or may be used for other purposes. When used in the production of a cement composition, the amount of gypsum compounded in the compounding section 51 can be reduced or eliminated by containing the dihydrate of calcium sulfate in the sulfur-containing compound slurry.

The raw material slurry is continuously or intermittently supplied to the reaction unit 30 from the raw material slurry preparation unit 34. The raw material slurry preparation unit 34 is supplied with fine particle powder containing CaCO ₃ as a main component generated in the crushing unit 82 that pulverizes water and a clinker raw material (for example, limestone). In addition to this, CaO and ash generated in the heating unit 70 may be supplied to the raw material slurry preparation unit 34. Further, sludge containing cement or cement hydrate may be introduced into the raw material slurry preparation unit 34 in addition to the above-mentioned dust particles and washing dust particles. Examples of sludge include raw cons sludge obtained at a ready-mixed factory.

The exhaust gas desulfurized in the reaction section 30 is introduced into the cooling section 11 and flows through a flow path that exchanges heat with the cement clinker, and is introduced into the cement kiln section 10. As a result, the sulfur dioxide gas remaining in the exhaust gas can be effectively utilized. Further, when the exhaust gas contains NOx, it is possible to suppress the release of NOx into the atmosphere. The introduction route is not limited to this, and may be introduced into the cement kiln via a preheater unit, a calcining furnace, or the like. Further, a part of the exhaust gas in which the dust particles are reduced in the dust collecting section 19 may be introduced into the cement kiln section 10 by a flow path passing through the cooling section 11 by bypassing the reaction section 30.

At least a part of the sulfur-containing compound slurry prepared in the reaction unit 30 is introduced into the slurry concentration adjusting unit 36. Another part of the sulfur-containing compound slurry prepared in the reaction unit 30 may be oxidized in the oxidation treatment unit 42. The oxidation treatment is performed, for example, by bubbling air. In this way, a gypsum slurry containing gypsum can be obtained from the sulfur-containing compound slurry containing calcium sulfite. The gypsum slurry is dehydrated in the dehydration section 44 to obtain gypsum. The gypsum thus obtained is introduced into the compounding section 51.

The solid content concentration in the sulfur-containing compound slurry in the slurry concentration adjusting unit 36 is based on the temperature Tr of the cement clinker, the temperature Tm of the cement composition derived from the cement mill 52, and the ignition loss Ig of the cement composition. It is controlled by the concentration range. Specifically, the measured values of the temperature Tr of the cement clinker, the temperature Tm of the cement composition, and the ignition loss Ig of the cement composition are input to the control unit 38 as input signals. The control unit 38 selects one of the three input signals and outputs a control signal regarding the target value of the solid content concentration in the sulfur-containing compound slurry to the slurry concentration adjusting unit 36. The control unit 38 may select the signal that adjusts the solid content concentration most among the plurality of input signals. The slurry concentration adjusting unit 36 adjusts the solid content concentration in the sulfur-containing compound slurry based on the control signal from the control unit 38. The control unit 38 may have table data showing the relationship between the above-mentioned three measured values and the solid content concentration of the sulfur-containing compound slurry, or may have correlation type data.

It is not essential that the reaction unit 30 and the slurry concentration adjusting unit 36 are provided separately. In the modified example, the solid content concentration of the sulfur-containing compound slurry may be adjusted in the reaction section 30. In this case, the control signal from the control unit 38 may be input to the reaction unit 30. The measured value input to the control unit 38 is any one selected from the temperature Tr of the cement clinker, the temperature Tm of the cement composition derived from the cement mill 52, and the ignition loss Ig of the cement composition. There may be two or two.

The sulfur-containing compound slurry whose solid content concentration has been adjusted and the cement clinker stored in the silo 18 are introduced into the compounding section 51 in the crushing section 50. The cement clinker may be introduced after being temporarily stored in the silo 18, or may be introduced directly from the cooling unit 11. The temperature Tr of the cement clinker introduced into the compounding section 51 is, for example, 40 to 220 ° C.

In the compounding section 51, gypsum may be compounded if necessary. The sulfur-containing compound slurry contains at least one sulfite compound selected from the group consisting of a hemihydrate of calcium sulfite, calcium heavy sulfite (Ca (HSO ₂ ) ₂ ), and a double salt of calcium sulfite and calcium sulfate. It is preferable to do so. In this case, when the cement composition is 100 parts by mass, the cement clinker is preferably charged with 0.1 to 20 parts by mass of the sulfur-containing compound slurry in terms of the above sulfite compound in terms of anhydride (or calcium sulfite in terms of anhydride). , More preferably 0.15 to 15 parts by mass, still more preferably 0.2 to 10 parts by mass, and particularly preferably 0.25 to 5 parts by mass. Thereby, the compound can be smoothly pulverized while maintaining the content of the sulfurous acid compound in the obtained cement composition. When a double salt of calcium sulfite and calcium sulfate is contained, calcium sulfite in the double salt may be contained in the above-mentioned mass ratio. The mixing ratio of gypsum to cement clinker 100 parts by weight may be about 1.5 to 20 parts by weight converted to SO _3.

Formulations containing cement clinker, sulfur-containing compound slurry and optionally gypsum are introduced into the cement mill 52. The cement mill 52 may be a ball mill or a vertical mill. The temperature of the cement mill 52 tends to rise due to frictional heat during pulverization. Water is sprinkled into the cement mill 52 so that the temperature inside the cement mill 52 does not rise excessively. Therefore, when the sulfur-containing compound slurry contains an appropriate amount of water, it is possible to suppress an excessive temperature rise in the cement mill 52. Therefore, blending the sulfurous acid compound in the form of a slurry also contributes to reducing the amount of water sprinkled into the cement mill 52.

The temperature Tm of the cement composition at the outlet of the cement mill 52 may be 20 ° C. to 180 ° C., preferably 40 ° C. to 150 ° C., more preferably 50 ° C. to 140 ° C., and further preferably 60 to 60 ° C. It is 95 ° C. If the temperature Tm becomes too low, the water content of the sulfur-containing compound slurry tends to cause a hydration reaction with the cement composition. On the other hand, when the temperature Tm becomes too high, calcium sulfite tends to be oxidized and changed to calcium sulfate. That is, by setting the temperature Tm to the above-mentioned temperature range, the drying of the formulation proceeds at a sufficient rate while suppressing the oxidation of calcium sulfite. In addition, cement clinker, calcium sulfite and gypsum can be mixed sufficiently uniformly.

The cement composition thus obtained capable of reducing the elution amount of hexavalent chromium is housed in the silo 54. The ignition loss Ig (ig. Loss) of the cement composition may be, for example, 1.0 to 8.0% by mass.

Downstream of the particulate collection portion 19, a measuring instrument for measuring the SO ₂ concentration Sg of the exhaust gas may be installed. Moreover, the kiln inlet 10a, measuring device for measuring the SO ₃ concentration Sp in the dust may be installed. The SO ₂ concentration Sg may be controlled to 500 to 10,000 ppm by adjusting the sulfur content of the raw material supplied to the heating unit 71. The sulfur content of the raw material may be adjusted by changing the supply amount of the sulfur-containing raw material, or by changing the sulfur concentration in the sulfur-containing raw material.

In the present embodiment, the crushing section 50 includes a compounding section 51 and a cement mill 52, but is not limited thereto. For example, in the modified example, the cement clinker, the sulfur-containing compound slurry and the gypsum to be blended as needed may be directly introduced into the cement mill 52 and blended and pulverized in the cement mill 52. Further, the cement clinker and gypsum are blended in the compounding section 51, and the sulfur-containing compound slurry is sprayed on the compounding portion on a belt conveyor for transporting the compounding obtained from the compounding section 51 to the cement mill 52, and the cement mill 52 is used. Grinding may be performed.

In another modification, a control unit may be provided that adjusts the blending ratio of the sulfur-containing compound slurry to the cement clinker according to the chromium content of the cement clinker derived from the cement kiln unit 10. The chromium content of the cement clinker may be measured by sampling from the silo 18 at a predetermined frequency, or may be calculated from the chromium content contained in the raw material introduced into the heating unit 71.

The control unit calculates the amount of the sulfur-containing compound slurry to be blended in the cement clinker based on the input value of the chromium content of the cement clinker obtained as described above. The control unit may have table data showing the relationship between the cement chromium content and the blending amount of the sulfur-containing compound slurry, or may have correlation equation data between the two. The control unit calculates the blending amount of the sulfur-containing compound slurry using such data. Based on the calculation result, the control unit controls, for example, a flow rate control valve that adjusts the flow rate of the sulfur-containing compound slurry. In this way, the compounding ratio of the sulfur-containing compound slurry to the cement clinker can be adjusted. Since such a control is a slurry having fluidity, it can be carried out with a simple facility.

The method for producing the cement composition of the present disclosure may be carried out using any of the above-mentioned production devices 100, 101, 102 and 104. The method for producing a cement composition according to one embodiment includes a cement clinker manufacturing process in which a raw material containing sulfur is calcined to produce a cement clinker, and sulfite gas or an exhaust gas containing the same is absorbed by a raw material slurry to produce a sulfite. It has a reaction step of obtaining a sulfur-containing compound (sulfur-containing compound slurry) and a crushing step of pulverizing a compound containing a cement clinker and a sulfur-containing compound (sulfur-containing compound slurry) to obtain a cement composition.

The type of cement clinker obtained in the cement clinker manufacturing process is not particularly limited, and may be any of various Portland cements specified in JIS R 5210: 2003 “Portland cement”. According to the cement composition of the present embodiment, the elution of hexavalent chromium can be sufficiently suppressed. The total amount of chromium in the cement clinker may be, for example, 20 mg / kg to 250 mg / kg, 80 mg / kg to 200 mg / kg, or 100 to 150 mg / kg. The amount of water-soluble hexavalent chromium of the cement clinker measured according to the method described in the Cement Association Standard Test Method JCAS I-53-2018 may be, for example, 3 to 40 mg / kg, and may be 10 to 40 mg / kg. It may be kg or 20 to 30 mg / kg.

As an example, in the pulverization step, a cement clinker, a sulfur-containing compound slurry, and gypsum may be blended, and then the formulation containing these may be pulverized to obtain a cement composition. As another example, in the pulverization step, the cement clinker, the sulfur-containing compound slurry, and gypsum may be blended and pulverized at the same time. As yet another example, in the pulverization step, the cement clinker may be pulverized to some extent, then the sulfur-containing compound slurry and gypsum may be blended, and the obtained formulation may be further pulverized.

Examples of raw materials used in the cement clinker manufacturing process include sulfur-containing raw materials and clinker raw materials. However, it is not essential to use a sulfur-containing raw material, and the fuel may contain sulfur. Exhaust gas containing sulfurous acid gas is generated from the cement clinker manufacturing process in which cement clinker is manufactured using raw fuel containing sulfur. By bringing this exhaust gas into contact with the raw material slurry, a sulfur-containing compound slurry can be efficiently produced. In particular, since the gas between the kiln end of the cement kiln and the calciner contains a large amount of sulfur oxides, if the exhaust gas during this period is used, the sulfur-containing compound slurry containing a large amount of sulfites can be produced with sufficiently high efficiency. Can be manufactured. In the present disclosure, "between the kiln butt and the calcining furnace" includes the kiln butt, the calcining furnace, and the space between them.

When the chlorine bypass section is installed as a facility for extracting the exhaust gas from the kiln end of the cement kiln section to the calcining furnace, the gas may be extracted from the chlorine bypass section to obtain the exhaust gas. Further, the exhaust gas may be extracted from the kiln butt of the cement kiln. Since such exhaust gas has a high temperature (for example, 700 to 1200 ° C.), it may have a cooling step for cooling the exhaust gas to 400 ° C. or lower. By bringing such exhaust gas into contact with the raw material slurry, a sulfur-containing compound slurry can be efficiently prepared. A sulfur-containing compound slurry may be obtained by a lime method using a raw material slurry containing lime.

The manufacturing apparatus 100, 101, 102, 104 may be used based on the contents of the above-mentioned method for manufacturing a cement composition. Therefore, the contents described in the method for producing a cement composition can also be applied to an apparatus for producing a cement composition. Further, the description of the manufacturing apparatus 100, 101, 102, 104 and its modifications can be applied to the above-mentioned method for producing a sulfur-containing compound and the method for producing a cement composition. The cement composition manufacturing apparatus of the present disclosure can simultaneously manufacture a sulfur-containing compound slurry and desulfurize exhaust gas, and can also be provided with a slurry dehydration facility or the like for a solid matter after dehydration. It is no longer necessary to install a dedicated tank, weighing machine, or transportation equipment. Therefore, the introduction cost and the operation cost of the equipment can be sufficiently reduced. However, this disclosure does not exclude those equipped with such equipment.

FIG. 8 is a diagram showing still another embodiment of a manufacturing apparatus for manufacturing a sulfur-containing compound and a cement composition. In this embodiment, the equipment 105 for producing the cement composition has a first reaction unit 30C and a first reaction unit 30C for preparing an aqueous solution or slurry containing magnesium sulfite instead of the reaction unit 30 for preparing a sulfur-containing compound slurry containing calcium sulfite. It differs from the manufacturing apparatus 101 in that it includes a second reaction unit 32 for preparing a sulfur-containing compound slurry containing calcium sulfite by mixing an aqueous solution or slurry containing magnesium sulfite prepared in the reaction unit 30C with a calcium compound. .. Since the other elements are the same as those of the manufacturing apparatus 104 of FIG. 7, the differences from the manufacturing apparatus 104 will be described.

In the first reaction unit 30C, the exhaust gas containing sulfurous acid gas is absorbed by the aqueous solution containing magnesium hydroxide. As a result, an aqueous solution or slurry containing magnesium sulfite is obtained. Magnesium sulfite has a higher solubility in water than calcium sulfite, so that clogging of solids in the first reaction section 30C can be suppressed. To the aqueous solution or slurry prepared by the first reaction unit 30C, the raw material slurry is added from the raw material slurry preparation unit 34 in the second reaction unit 32 provided on the downstream side of the first reaction unit 30C. The raw material slurry is, for example, washed with water of fine particle powder containing CaCO ₃ as a main component, dust particles containing CaO and / or Ca (OH) ₂ generated in a chlorine bypass portion, which are generated when crushing a clinker raw material. Includes at least one selected from the group consisting of the washed dust particles thus obtained and sludge containing cement and / or cement hydrate. As a result, the second reaction unit 32 can obtain a sulfur-containing compound slurry containing calcium sulfite.

The first reaction unit 30C needs to maintain a certain degree of airtightness in order to suppress the exhaust gas from being released to the outside. Therefore, it is preferable to reduce the maintenance frequency. In the present embodiment, magnesium sulfite, which has a higher solubility in water than calcium sulfite, is first produced in the sulfite, and then a sulfur-containing compound slurry containing calcium sulfite is prepared in the second reaction unit 32. Therefore, it is possible to reduce the maintenance frequency of the first reaction unit 30C by scaling calcium sulfite and improve the stability of the process.

In the present embodiment, magnesium hydroxide is used in the first reaction section 30C, but the present invention is not limited to this, and a salt capable of producing a sulfurous acid compound having a higher solubility in water than calcium sulfite can be used. it can. As such a salt, an alkaline earth metal or a salt of an alkali metal different from Ca and Mg can be used, and examples thereof include potassium hydroxide and calcium hydroxide.

Although some embodiments have been described above, the present disclosure is not limited to the above-described embodiments. For example, the manufacturing apparatus 104 of FIG. 7 includes a reaction unit 30 similar to that of FIG. 4, but is not limited thereto. For example, instead of the reaction unit 30, a reaction unit 30A for obtaining a granular sulfur-containing compound by a spray-drying method as shown in FIG. 5 may be provided. Further, the reaction unit 30B for obtaining the granular sulfur-containing compound by the fluidized bed method as shown in FIG. 6 may be provided. In these cases, the slurry concentration adjusting unit 36 of FIG. 7 may not be provided, or the powdery sulfur-containing compound may be replaced with a sulfur-containing compound slurry preparation unit that slurries.

The heating process of the present disclosure will be described below with reference to some specific examples. However, the present disclosure is not limited to the following experimental examples.

Using a tube furnace and a rotary kiln, the heating process was performed as follows to evaluate the product.

[Baking in a tube furnace]
The following raw materials were prepared.
(1) Crushed waste gypsum board (2) Waste plastic (RPF)

150 parts by mass of waste plastic (RPF) was mixed with 100 parts by mass of crushed waste gypsum board and mixed to prepare a raw material. 10 g of this raw material is placed in an alumina ship-shaped crucible, and a tube furnace (manufactured by Koyo Thermos System Co., Ltd .: KTF434-S) is used for 60 minutes at the temperature shown in Table 1 under a distribution atmosphere of nitrogen gas 2 L / min. It was heated.

The composition of the product (ash) remaining in the crucible was analyzed by the XRD-Rietveld method. An X-ray diffractometer (manufactured by Bruker AXS Co., Ltd., accelerating voltage: 30 kV, current 10 mA, tube: Cu) was used for the composition analysis. The Rietveld analysis of the obtained powder X-ray diffraction pattern was performed, and the amounts of gypsum (CaSO ₄ ), calcium sulfide (CaS), calcium oxide (CaO) and quartz (SiO ₂ ) were measured. Analysis software (Topas, manufactured by Bruker Ax Co., Ltd.) was used for the Rietveld analysis.

The results of the composition analysis obtained by the XRD-Rietveld method are as shown in Table 1. The content of sulfur in the form of sulfide, that is, sulfur contained as sulfide, was determined by the following formula using the amount of CaS measured by the XRD-Rietveld method. The results are as shown in Table 1.
[Molecular weight of CaS] / [Molecular weight of CaS: 72] x [Molecular weight of S: 32] = [Sulfur content in sulfide form]

As shown in Experimental Examples 1 to 3, gypsum reacted in each case to produce CaS or CaO. CaO is a residue after CaSO ₄ reacts with the above reaction formula (1) to generate sulfurous acid gas. The gas generated during the reaction contained sulfite gas. In addition, from the results in Table 1, it was confirmed that the higher the heating temperature, the more the decomposition of the plaster tends to proceed.

[Burning with rotary kiln]
The following raw materials were prepared.
(1) Crushed waste gypsum board (2) Sawdust (glulam)

A mixture of 100 parts by mass of crushed waste gypsum board and sawdust in the ratio shown in Table 2 was used as a raw material. Using a screw feeder, the raw material was put into a rotary kiln furnace (manufactured by Chuo Kakoki Co., Ltd.) and heated at 950 ° C. in a flow atmosphere of 30 L / min of air. The rotation speed of the rotary kiln was 3 rpm, and the inclination angle was 5%. The composition of the product after heating was analyzed by the same method as in Experimental Examples 1 to 3, and the content of each component and the content of sulfur in the form of sulfide were determined.

In Experimental Examples 4 to 6, gypsum (CaSO ₄ ) reacted to generate CaS or CaO, and the higher the proportion of sawdust, the more the gypsum reaction tended to proceed. In the case of Experimental Example 7 in which sawdust was not added, gypsum did not react under the above-mentioned firing conditions. CaO is a residue after CaSO ₄ reacts with the above reaction formula (1) to generate sulfurous acid gas. In Experimental Example 4 to Experimental Example 6, a gas having a sulfur dioxide gas concentration of 5000 ppm could be obtained.

According to the present disclosure, there is provided a method for producing a sulfur-containing compound and a cement composition, which can produce a sulfur-containing compound and a cement composition effective for reducing the elution of hexavalent chromium at low cost. Further, a sulfur-containing compound and a cement composition which can be produced at a low production cost and are effective in reducing the elution of hexavalent chromium are provided. Further, an apparatus for producing a sulfur-containing compound capable of producing a sulfur-containing compound effective for reducing the elution of hexavalent chromium at a low production cost is provided.

10 ... Cement kiln part, 10a ... Kiln butt, 11 ... Cooling part, 12 ... Bypass part, 16 ... Preheater part, 17 ... Cooling part, 18 ... Silo, 19 ... Dust collecting part, 30, 30A, 30B ... Reaction part, 30C ... 1st reaction unit, 31 ... Washing unit, 32 ... 2nd reaction unit, 34 ... Raw material slurry preparation unit, 36 ... Slurry concentration adjustment unit, 38 ... Control unit, 42 ... Oxidation treatment unit, 44 ... Dehydration unit, 50 ... Crushing part, 51 ... Mixing part, 52 ... Cement mill, 54 ... Silo, 60 ... Desulfurizing part, 70, 71 ... Heating part, 82 ... Crushing part, 100, 101, 102, 104, 105 ... Manufacturing equipment.

Claims (21)

A heating process that heats sulfur-containing waste to obtain sulfurous acid gas,
Sulfur, which comprises a reaction step of reacting the sulfurous acid gas with an alkali source containing at least one selected from the group consisting of an alkali metal compound and an alkaline earth metal compound to obtain a sulfur-containing compound containing a sulfite. Method for producing contained compound. The method for producing a sulfur-containing compound according to claim 1, wherein an ash containing sulfide is obtained in the heating step. The method for producing a sulfur-containing compound according to claim 2, wherein the sulfur content of the ash contained as the sulfide is 1 to 44% by mass. In the heating step, any one of claims 1 to 3 in which a carbon source containing at least one selected from the group consisting of paper, waste plastic, carbon fiber, biomass, coal and petroleum is heated together with the sulfur-containing waste. The method for producing a sulfur-containing compound according to the section. The method for producing a sulfur-containing compound according to any one of claims 1 to 4, wherein in the heating step, a carbon source of 10 to 1000 parts by mass is heated together with 100 parts by mass of the sulfur-containing waste. It has a waste crushing step of crushing the sulfur-containing waste before the heating step.
The method for producing a sulfur-containing compound according to any one of claims 1 to 5, wherein the sulfur-containing waste contains at least one selected from the group consisting of sulfate, sulfide and sulfur. In the heating step, a gas containing the sulfur dioxide gas at a concentration of 100 ppm to 5% was obtained.
The method for producing a sulfur-containing compound according to any one of claims 1 to 6, wherein in the reaction step, the gas is brought into contact with the alkaline source. The sulfur-containing compound according to any one of claims 1 to 7, wherein the sulfite contains at least one selected from the group consisting of calcium sulfite, sodium sulfite, magnesium sulfite, calcium sulfite, sodium bisulfite and magnesium sulfite. Manufacturing method. The method for producing a sulfur-containing compound according to any one of claims 1 to 8, wherein in the heating step, a sulfur-containing waste different from the sulfur-containing waste is heated together with the sulfur-containing waste. The sulfur according to any one of claims 1 to 9, wherein in the heating step, a silicon source containing a silicate compound and / or an aluminum source containing aluminum oxide is heated and reacted together with the sulfur-containing waste. Method for producing contained compound. When the alkali source contains the alkali metal compound,
The alkali metal compound is sodium carbonate, sodium hydrogen carbonate, sodium hydroxide,
Includes at least one selected from the group consisting of sodium citrate, sodium formate, potassium carbonate, potassium hydrogen carbonate and potassium hydroxide.
When the alkaline source contains the alkaline earth metal compound,
The sulfur-containing compound according to any one of claims 1 to 10, wherein the alkaline earth metal compound contains at least one selected from the group consisting of calcium carbonate, calcium hydrogen carbonate, slaked lime, calcium oxide, and calcium chloride. Manufacturing method. As the alkali source, fine particle powder containing calcium carbonate as a main component generated when the raw material of cement clinker is crushed, dust particles of a calcium compound extracted from a chlorine bypass portion, and water-washed dust particles obtained by washing the dust particles with water. The sulfur-containing compound according to any one of claims 1 to 11, which utilizes at least one selected from the group consisting of sludge containing at least one of cement and cement hydrate, and ash generated in the heating step. Production method. It has a slurry preparation step for preparing a raw material slurry containing the alkali source and water.
The method for producing a sulfur-containing compound according to any one of claims 1 to 12, wherein the raw material slurry is used as the alkali source in the reaction step. The method for producing a sulfur-containing compound according to claim 13, wherein the ratio of the solid content in the raw material slurry is 0.1 to 90% by mass. The method for producing a sulfur-containing compound according to any one of claims 1 to 14, further comprising an introduction step of blowing the exhaust gas generated in the reaction step into a kiln for producing cement clinker or magnesia clinker. A heating unit that heats sulfur-containing waste to obtain sulfurous acid gas,
Sulfur, which comprises a reaction section for reacting the sulfurous acid gas with an alkali source containing at least one selected from the group consisting of an alkali metal compound and an alkaline earth metal compound to obtain a sulfur-containing compound containing a sulfite. Equipment for producing contained compounds. The apparatus for producing a sulfur-containing compound according to claim 16, wherein a kiln for producing cement clinker or magnesia clinker is used as the heating unit. A sulfur-containing compound obtained by the production method according to any one of claims 1 to 15. A method for producing a cement composition, comprising a step of obtaining a cement composition using the sulfur-containing compound obtained by the production method according to any one of claims 1 to 15 and a cement clinker. A cement composition is obtained by using one or both of the sulfur-containing compound obtained by the production method according to any one of claims 1 to 15 and the ash obtained in the heating step, cement clinker, and gypsum. A method for producing a cement composition having a step. A cement composition obtained by the production method according to claim 19 or 20.