KR100316589B1 - The Manufacturing Method of Silicic Acid Potassium Fertilizer utilizing Sewage Sludge - Google Patents

Abstract

The present invention relates to potassium oxide (K ₂ ) with respect to 100 parts by weight of sewage sludge (the same as building standards) in order to recycle sewage sludge produced in a sewage terminal treatment plant as a main raw material for the production of potassium silicate fertilizer. 13 to 17 parts by weight in terms of O) and 3 to 4 parts by weight of magnesium (Mg) compound in terms of magnesium oxide, or to promote solubilization of silicic acid and solubilization of potassium and to reduce the solubility of potassium. As an additive, 0.1-5 parts by weight of aluminum (Al) and calcium (Ca) components in the form of the respective oxides (Al ₂ O ₃ and CaO) (hereinafter identical) to 100 parts by weight of sewage sludge are added alone or in combination. By mixing the mixture in a temperature range of 900 to 1100 ° C. and a firing time of 10 to 25 minutes, the organic component of the sludge is combusted and the combustor (inorganic component) is added to the additive elements such as potassium. Potassium silicate fertilizer is prepared by the method of phase-transferring to potassium feldspar by solid phase reaction.

Description

Manufacture method of potassium silicate fertilizer using sewage sludge {The Manufacturing Method of Silicic Acid Potassium Fertilizer utilizing Sewage Sludge}

In the present invention, an organic sludge generated in a sewage terminal treatment plant is mixed with an appropriate amount of potassium compound and other functional aids, which are one of the main fertilizers, and the mixture is directly calcined to burn the organic material in the sludge and at the same time, the silicon contained in the sludge The present invention relates to the disposal and recycling of sewage sludge, which reacts with added potassium to phase change to potassium feldspar, thereby allowing the residue to be directly recycled as potassium silicate fertilizer.

In general, all the sewage sludge generated from sewage treatment plants in the whole country is 1,276,000 tons, 76% of which are disposed of in landfills, 20.3% of which are disposed of in the sea, and only 3.5% are recycled by compost.

However, the landfill method is expected to be banned after 2001 due to the difficulty of securing landfills and the possibility of causing secondary environmental pollution, which is not appropriate as a disposal method. Therefore, it is urgent to develop alternative treatment technologies. .

Currently, the alternative technique of fluidized bed incineration has been widely considered, but this method also has the advantages of stabilization and reduction of sewage sludge as an intermediate treatment method, but it requires expensive facility and treatment costs and requires the disposal of incineration ash. There is this.

On the other hand, potassium silicate fertilizer was developed in 1978 as a recycling method for coal ash in Japan, but currently commercialized, but only registered as a fertilizer in Korea, which has not yet been produced.

In Japan, the method of manufacturing potassium silicate fertilizer, which uses coal ash as the main raw material, also maintains the quality of the manufacturing process and products consistently because the chemical composition and physical properties of coal ash are greatly changed depending on the type of raw coal and operating conditions of thermal power plants. Not only are there limitations in application such as difficulty, but most coal ashes contain a large amount of heavy metals, which may cause secondary pollution.

The purpose of the present invention is to solve the limitations and problems of coal ash as a main raw material of the conventional sewage sludge disposal technology and potassium silicate fertilizer, and to burn and inorganicize and stabilize the organic components contained in the sewage sludge at high temperature. The phase change of the inorganic material (incineration ash) to potassium feldspar makes it possible to directly recycle it as a value-added potassium silicate fertilizer.

1 is a process chart for explaining the manufacturing method of the present invention.

The present invention converts the potassium (K) compound to the potassium oxide (K ₂ O) basis (hereinafter equal to) based on 100 parts by weight of sewage sludge (the same as the building basis), and 13 to 17 parts by weight of magnesium (Mg) compound. 3-4 parts by weight of magnesium oxide, based on magnesium oxide, was granulated to a particle diameter of about 2 mm while drying with a rotary drum dryer, and then calcined at 900 to 1100 ° C. for 10 to 25 minutes using a calcination furnace to obtain organic components of the sludge. It is composed of producing potassium silicate fertilizer by burning the solid and reacting the combustion material (inorganic component) with additional elemental components such as potassium and phase-transferring to potassium feldspar.

However, when the calcined product has a chemical composition of Al ₂ O ₃ and CaO content of less than 15% by weight and less than 7% by weight, respectively, the aluminum (Al) and calcium (Ca) components may be formed in the respective oxide forms (Al ₂ O ₃ and 0.1-5 parts by weight can be added singly or in combination with respect to 100 parts by weight of sewage sludge in terms of CaO). That is, at least one component selected from aluminum and calcium may be added at 0.1-5 parts by weight based on 100 parts by weight of sewage sludge.

Hereinafter, the present invention will be described in detail.

The present invention is to inorganicize organic sewage sludge in a one step process called firing process, unlike the existing disposal method, which can be completely disposed only after reducing or stabilizing waste, or after incineration ash disposal. / Stabilization and functionality at the same time allows the disposal of sewage sludge completely by allowing the product to be directly recycled as a value-added resource without reprocessing.

Sewage sludge is a combustible material that contains more than 40% of organic matter and can generate calorific value of about 2500kcal / kg · DS, so it can be used as an auxiliary energy source in the production of potassium silicate fertilizer, which needs to be calcined at high temperature to phase transition temperature. In addition to reducing the firing energy, it is possible to produce more uniform potassium silicate fertilizer because the spatio-temporal content distribution of inorganic elements (particularly silicon and aluminum) contained in these sludges is much more stable than coal ash. can do.

The main role of the sewage sludge used as the main raw material in the present invention is to supply the silicic acid in the potassium silicate fertilizer component of the object of the present invention, there is no need to specifically limit their properties in applying the present invention, but the effective aspect and In view of meeting the fertilizer process specification (25% or more of S-SiO2), the chemical composition of the incineration residue is 40% or more by weight of SiO ₂ , 17% by weight or more of Al ₂ O ₃ , and 20% by weight or less of CaO. desirable.

The potassium compound used as the main additive in the present invention acts as a reactive agent to potassium feldspar by combining with Si or Al components in sewage sludge. Examples of the potassium compounds that can be used include potassium hydroxide (KOH) and potassium carbonate (K _2). CO ₃ ), potassium chloride (KCl), and the like, which are potassium-containing materials, which are mixed so that the chemical composition of the calcined residue is 30% by weight of SiO ₂ and the content of potassium is 23% by weight or more as K ₂ O. Any substance containing potassium to the extent possible can be used.

The magnesium component used as another main additive in the present invention is selectively added only when the magnesium content in the sewage sludge inorganic component, which is the main raw material, is less than 8% by weight in terms of magnesium oxide, and its main role is fertilizer process standard (C -MgO 3% or more) to reinforce the goto components of the product, and incidentally unreacted part of the potassium remaining in water solubility, an example of the magnesium compound that can be used is talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ), serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ), magnesium oxide (MgO), magnesium hydroxide (Mg (OH) ₂ ), magnesium carbonate (MgCO ₃ ), and the like. Among them, the use of talc is most preferable in view of economics and ease of handling.

Further adjuvants of the aluminum and calcium components and firing residues Al ₂ O ₃ and CaO content is 15% by weight, 7% by weight is less than when the end-soluble (S-SiO ₂₎ and obtain insoluble (CK ₂ O of the article for sale the addition of each C-MgO) increases and decreases the water solubility (WK ₂ O), it can be added alone or in combination, preferred materials are aluminum hydroxide powder or aluminum oxide powder for aluminum, shell or limestone for calcium Calcium carbonate series.

1 is a process chart for achieving a method for recycling sewage sludge as a raw material for producing potassium silicate fertilizer of the present invention, wherein the main materials in the manufacturing process are sewage sludge, potassium compounds and magnesium compounds, and aluminum compounds and Calcium compounds may be added.

Each mixing ratio is 13 to 17 parts by weight of potassium compound as potassium oxide, and other auxiliaries may be added alone or in combination of 0.1 to 5 parts by weight based on 100 parts by weight of dry sludge.

The oxide composition of the final baked product in the mixing ratio range is _{50%> SiO 2 ≥30%,} K 2 O≥23%, preferably _{25%> Al 2 O 3 ≥13} % than MgO≥5% (, 10 %> CaO≥5%), take each material appropriately and mix it homogeneously with a blender, and dry it by granulating with a rotary drum type dryer to a particle diameter of about 2mm.

The dried mixture is put into a firing furnace having a firing temperature of 900 to 1100 ° C. to prepare potassium silicate fertilizer by firing for 10 to 25 minutes.

Embodiments of the present invention are as follows.

<Example 1>

Gwangju sewage sludge (Gloss: 39.3%, SiO ₂ 51.97%, Al ₂ O ₃ 24.25%, MgO 2.06%, CaO 2.99%, K ₂ O 2.70%) 16 parts by weight of potassium hydroxide (based on potassium oxide, hereinafter identical), 4 parts by weight of talc (based on magnesium oxide, hereinafter identical) and 1.5 parts by weight of aluminum oxide (Al ₂ O ₃ ) were added and mixed homogeneously. The mixture was granulated to around 2 mm, dried, put into a kiln, and fired at a temperature of 950 ° C. for 10 minutes.

As a result of analyzing the fertilizer components of the calcined product is shown in Table 1 (hereinafter the same).

<Example 2>

16 parts by weight of potassium hydroxide, 4 parts by weight of talc and 3 parts by weight of calcium carbonate (CaCO ₃ ) were added to the 100 parts by weight of sewage sludge of Example 1, mixed homogeneously, and calcined in the same manner as in <Example 1>.

<Example 3>

Aluminum oxide (Al ₂ O ₃ ) was further added to 100 parts by weight of sewage sludge in the same mixing composition as in Example 2, mixed homogeneously, and calcined in the same manner as in <Example 1>.

<Example 4>

In the mixing composition of Example 2, the amount of potassium hydroxide was reduced from 16 parts by weight to 14 parts by weight and calcined in the same manner as in the other Example 1.

<Comparative Example 1>

The same procedure as in Example 1 was performed except that aluminum oxide was not added.

<Comparative Example 2>

The same procedure as in Example 1 was performed except that aluminum oxide and talc were not added.

From the above results, in order to make potassium silicate fertilizer for the rainy season Gwangju sewage sludge (containing the largest amount of inorganic matters per year), 4 parts by weight of high soil component with magnesium oxide, 3 parts by weight of calcium component with calcium oxide and potassium component per 100 parts by weight of dry sewage It was found that potassium oxide should be added at least 14 parts by weight up to 17 parts by weight.

The calcium component reduced potassium solubility (unreacted rate) and increased solubilization rate of silicic acid, and the solubilization rate was reduced and solubilized by adding 1.5 parts by weight of aluminum oxide instead of calcium or in combination with calcium. The rate was increased, but the effect was less than that of adding calcium alone.

Since more than 90% of the total silicic acid content was eluted into soluble silicic acid under the mixing conditions of <Example 2>, even if the amount of potassium was further increased, the effect was small, but remained unreacted to increase the amount of water-soluble potassium. Only results were ineffective, both economically and in terms of fertilizer performance.

<Example 5>

Potassium hydroxide (KOH) in the adjuvant of Example 2 was replaced with potassium chloride (KCl) and mixed and calcined in the same mixing composition and method as in Example 2.

As a result of analyzing the fertilizer components of the calcined product is shown in Table 2 (the same).

<Example 6>

Potassium hydroxide (KOH) in the adjuvant of Example 2 was replaced with potassium carbonate (K ₂ CO ₃ ) and mixed and calcined in the same mixing ratio and method as in Example 2.

The above examples show that KOH is the most reactive among KOH, K ₂ CO ₃ , and KCl as the potassium compound, and KCl showed the smallest reactivity, but potassium silicate fertilizer of sewage sludge can be used.

However, considering the ease of handling, K ₂ CO ₃ is preferred.

<Example 7>

Gwangju sewage sludge generated during sewage treatment during dry season (Gross Loss: 53.0%, Inorganic material after loss of ignition SiO ₂ 46.81, Al ₂ O ₃ 22.56, MgO 2.57, CaO 4.95, K ₂ O 2.55) 13 parts by weight of potassium carbonate (based on potassium oxide), 3 parts by weight of talc (based on magnesium oxide) and 2.5 parts by weight of calcium carbonate (based on calcium oxide) were added and fired in the same manner as in Example 1.

As a result of analyzing the fertilizer components of the calcined product is shown in Table 3 (the same).

<Example 8>

Naju sewage sludge produced during sewage treatment during the rainy season (loss on ignition: 36.7%, after inorganic loss of SiO ₂ 51.76%, Al ₂ O ₃ 24.04%, MgO 2.22%, CaO 3.25%, K ₂ O 2.70%) Mixing and baking were carried out in the same manner as in Example 2.

<Example 9>

Naju sewage sludge generated during sewage treatment in dry season (Gloss loss: 56.4%, after loss of minerals, SiO ₂ 50.77%, Al ₂ O ₃ 19.82%, MgO 2.31%, CaO 5.20%, K ₂ O 3.23%) Mixing and baking were carried out in the same manner as in Example 7.

<Example 10>

Jeonju Sewage Sludge generated during Sewage Treatment during Rainy Season (Gloss Loss: 41.3%, after Loss of Inorganic Minerals SiO ₂ 54.18%, Al ₂ O ₃ 19.18%, MgO 1.93%, CaO 7.14%, K ₂ O 2.87%) Mixing and baking were carried out in the same manner as in Example 2.

<Example 11>

100 wt% of Jeonju Sewage Sludge produced from sewage treatment during dry season (Gloss loss: 58.4%, after inorganic loss of SiO ₂ 42.96%, Al ₂ O ₃ 21.19%, MgO 2.34%, CaO 8.37%, K ₂ O 2.62%) 13 parts by weight of potassium carbonate (based on potassium oxide) and 3 parts by weight of talc (based on magnesium oxide) were added to the parts (based on the building) and fired in the same manner as in Example 1.

<Comparative Example 3>

Sewage sludge (without potassium carbonate and talc) of Example 11 was mixed and calcined in the same manner as in Example 7.

The above examples show that in the production of potassium silicate fertilizer using sewage sludge, the addition rate of the potassium component and the clay soil component is controlled by the loss of ignition, that is, the organic matter content, which varies according to the generation time and place of the sewage sludge.

The difference of elemental chemical composition in sewage sludge inorganic solids, except for calcium, has no significant effect on the performance of potassium silicate fertilizer using sewage sludge. It is shown that the sewage sludge potassium silicate fertilization technology of the present invention can be applied to all sewage sludges by controlling and administering the addition amount of potassium and high soil components in proportion to the change range (about 20 wt%).

However, the calcium content of sewage sludge varies significantly depending on the sewage terminal treatment plant (particularly, the content varies more than 10% by weight depending on the type of flocculant used, whether polymer or lime). It is necessary to add it.

That is, when the calcium content in the inorganic solids of sewage sludge exceeds 8% by weight of calcium oxide, as shown in <Example 11> and <Comparative Example 3>, the addition of the calcium component is rather the performance of the prepared potassium silicate fertilizer Resulted in lowering.

The present invention has the same principle as the conventional incineration method in that it incinerates and stabilizes organic components of sewage sludge, but has a fertilizer accelerator such as calcium and aluminum, and a material having a fertilizer function such as potassium and goto components in sewage sludge. By adding and mixing, firing at high temperature, burning organic matter, and reacting inorganic residues and additives remaining in the combustion process, the final residue is converted into potassium silicate fertilizer having a slow-acting fertilizer function rather than an incineration material for secondary treatment. It has the effect of allowing direct recycling without a process.

In addition, as can be seen through the above embodiment, the manufacturing method of the present invention can be utilized as a raw material for the production of potassium silicate fertilizer regardless of the place time of sewage sludge, so that the object to be treated as waste causing environmental pollution Wastewater sludge can be recycled as a raw material of eco-friendly agricultural materials, namely, slow-fertilizer fertilizers that can improve the agricultural productivity and economic efficiency due to long-term inefficiency. It has the effect of diversifying and adding value to the environmental and agricultural benefits of sewage sludge, as well as the added value of the sewage sludge, while utilizing the heat of combustion of sewage sludge as an auxiliary energy source for the manufacture of slow-release fertilizer. It is effective in reducing costs.

In addition, the present invention can be widely applied to other waste materials containing a large amount of organic matter, such as sewage sludge, that is, a recycling technology such as paper sludge.

Claims (3)

13 to 17 parts by weight of potassium compound based on potassium oxide (K ₂ O) and 3 to 4 parts by weight of magnesium compound based on magnesium oxide were added to 100 parts by weight of sewage sludge to form a mixture, followed by molding and drying. And a method for producing potassium silicate fertilizer using sewage sludge, which is fired at a temperature of 900 to 1100 ° C. for 10 to 25 minutes. The method for producing potassium silicate fertilizer using sewage sludge according to claim 1, wherein the potassium compound is one selected from potassium carbonate, potassium chloride and potassium hydroxide. According to claim 1, wherein when the calcined product has a chemical composition of Al ₂ O ₃ and CaO containing less than 15% by weight and 7% by weight of romium, respectively, at least one selected from the aluminum and onium components of sewage based on the respective oxide A method for producing an onium silicate fertilizer using sewage sludge, which is added in an amount of 0.1-5 dourom with respect to 100 dimethyl part of sludge.