KR100416518B1 - Manufacturing method of refining phospho-gypsum for cement - Google Patents

Abstract

The present invention is a method for preparing a phosphate tablet gypsum for cement by refining gypsum by-produced in the process of wet phosphate gypsum.

In the conventional method of preparing phosphate refined gypsum for cement, since Busan gypsum, which is a raw material, was produced in the wet phosphate manufacturing process of Isu Gypsum, there are a lot of impurities in Busan gypsum. (Washing Briquetting Proces).

However, a few years ago, wet phosphate plants were converted to half-water and half-water processes to improve the yield and process function of phosphoric acid, which drastically reduced impurities in Busan gypsum. The meaning of public methods has disappeared.

That is, the phosphate refined gypsum for cement can be produced efficiently and economically by the neutralization, high pressure steam method or the neutralization method of the present invention.

Description

Manufacturing method of phosphate refined gypsum for cement {MANUFACTURING METHOD OF REFINING PHOSPHO-GYPSUM FOR CEMENT}

The present invention relates to a method for preparing phosphate gypsum for cement, and more particularly, to a method for preparing phosphate gypsum for cement by refining gypsum by-produced in the wet phosphate manufacturing process of half-water, dihydrate gypsum.

In general, gypsum is one of the essential raw materials for cement, which is used for the purpose of improving the cement coagulation delay and initial strength, reducing expansion shrinkage, and resistance to sulfates.

Previously, only natural gypsum was used to make cement, but since the mid-1960s, the wet and gypsum phosphoric acid plant was built and operated, resulting in the production of gypsum from the phosphoric acid manufacturing process (hereinafter referred to as "phosphate gypsum"). This phosphate gypsum is of high quality (more than 90% of CaSO ₄ · 2H ₂ O), which is inevitably used as a gypsum for cement, but contains a small amount of impurities (phosphate, hydrofluoric acid, organic matter, etc.) that are not suitable for direct use The purification method was needed.

In Japan, the ONODA RefiningGranulation process was developed and commercialized in 1957, and the Washing Briquetting process was developed in Europe. There is a significant difference between the two methods in terms of refining technology (treatment of impurities, manufacturing facilities), but the quality of each other's refined product cannot be recognized. Table 1 below shows the main purification techniques of the two existing methods.

However, the above-described firing, granulation method, washing method, and molding method have very uneconomical problems in terms of refining facilities and energy consumption. In addition, the firing and granulation process removes dicalcium phosphate sandwiched between crystal lattice of gypsum. In order to purify, it is necessary to consume the firing equipment and fuel, and the cleaning and molding method has to overcome the difficulties of the various stages of the cleaning equipment and wastewater treatment. Therefore, the object of the present invention is to solve the above problems. , Sintering, assembly, cleaning, and shaping methods are very economical in terms of refinery and energy consumption, as well as fuel consumption and sintering in sintering and assembly processes, and The present invention provides a method for producing a phosphate refined gypsum for cement that can overcome the difficulties. In order to realize the above object, the present invention provides a semi-finished gypsum. Alkaline materials are added to the phosphate phosphate gypsum produced in the process of phosphoric acid production to neutralize the hydrogen ion concentration of phosphate gypsum from neutral to alkaline, and then the vapor pressure of 3-5Kg / ㎠ and the saturation temperature of the steam pressure 140 It is characterized in that it is made to elute the poorly soluble phosphoric acid to be ℃ ℃ purified by tricalcium phosphate in an insoluble state.

The present invention is a method for producing a phosphate refined gypsum for cement by refining gypsum rule produced in the wet phosphate manufacturing process of half-water and Isu gypsum. Several years ago, a domestic phosphate plant was developed to improve the yield and process function of phosphoric acid. The dihydrate gypsum process was divided into half and dihydrate gypsum processes, and the impurities of gypsum produced therefrom were significantly reduced as shown in Table 2 below. Water-soluble phosphate (water soluble P ₂ O ₅ ) and some of poorly soluble phosphate (CaH ₄ (PO _{4) 2} H ₂ O) and water-soluble fluorine (HF, H ₂ SiF ₆₎ ) Can be purified only by neutralization of alkali addition. Therefore, the process and equipment for refining gypsum produced by the half-water and dihydrate gypsum method can be greatly simplified. Water soluble phosphate, a part of poorly soluble phosphate, and water soluble fluorine are refined, and dicalcium phosphate (CaHPO ₄ · 2H ₂ O) sandwiched between gypsum crystal lattice is decomposed by instantaneous high-pressure steam thermal shock. Purification with tricalcium phosphate (Ca ₃ (PO ₄ ) ₂ ), and the neutralization method is a method of refining a part of water-soluble impurities and poorly soluble impurities with tricalcium phosphate in an insoluble state only by adding neutralization of alkali materials. The amount of dicalcite phosphate sandwiched between the crystal lattice of gypsum remaining after neutralization is very small (0.15% or less), and the effect of cement delaying condensation is very small. This is also demonstrated in the experiment of "Example". Moreover, since the purpose of adding gypsum to cement is to delay the coagulation of cement, the residual amount of phosphoric acid may be advantageous to control the coagulation of cement. The manufacturing process is shown in Figure 1. Figure 1. Manufacturing process diagram of phosphate refined gypsum for cement Table 3 below shows the method for refining phosphate gypsum for cement based on the gypsum produced by phosphate in the process of half-water and Isu gypsum. Chemical composition of phosphate tablets for cement prepared by the above two methods are shown in Table 4 below. All of the water-soluble phosphate (water soluble P ₂ O ₅ ) and the poorly soluble phosphate (CaH ₄ (PO ₄ ) ₂ · H ₂ O) that affect the coagulation delay of the cement are added to the It can be seen that it was changed to tricalcium phosphate (Ca ₃ (PO ₄ ) ₂ ) in an insoluble state which does not affect the condensation of. 3. Example 1 Gypsum used in the Examples of Gypsum and Gypsum Phosphate Gypsum produced by the neutralization and high-pressure steam method of gypsum produced in the process of phosphate production of half-water and gypsum Three kinds of gypsum were prepared by the neutralization method, phosphate refined gypsum (N) for cement, and phosphate gypsum (O) for cement produced by the firing and assembly process. Their chemical composition is shown in Table 5 below, and their X-ray diffraction analysis is shown in Figure 2. NS: Phosphate refined gypsum for cement produced by the neutralization and high pressure steam method of the present invention N: The neutralization method of the present invention Phosphate refined gypsum for cement O: Phosphate refined gypsum for cement manufactured by conventional firing / assembly process Figure 2. XRD of Gypsum ② Cement Clinker The cement clinker used in the examples is ordinary cement clinker and its chemical composition, mineral composition and X-ray diffraction analysis are shown in Table 6 and Figure 3. Figure 3. XRD of the clinker 2) Test Cement 1) -② Gypsum of 1) -① was added and pulverized in the cement clinker of Clause 1) -② to make the test cement. The powder and SO ₃ contents of the test cement are shown in Table 7. 3) Physical Performance of Cement Table 8 below shows the physical performance of experimental cement (Table 7). Settling time The settling time of cement using three different types of gypsum is delayed as the amount of added gypsum increases, but the difference according to the type of gypsum is unacceptable and the management range of these cements is stable. Compressive strength The compressive strength of cement using three different types of gypsum is unacceptable and all cements meet the KS. Regardless of the type and amount of gypsum, the stability of cement has little difference. All cements have an expansion rate of 0.10% or less, which is much lower than the Korean Industrial Standard (KS) upper limit of 0.80%. 4) Cement Hydration Reaction ① Hydration Product Hydration products according to the hydration reaction of cement were examined by X-ray diffraction analysis (XRD). The hydration products and the timing of their formation are the same for all cements, regardless of the gypsum used. Shortly after hydration, the amount of aluminate mineral and gypsum was small, but ethrinzite (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) was produced. Calcium silicate was also formed as the hydration progressed. Gel hydrate and calcium hydroxide (Ca (OH ₂ ) are produced. Hydration products according to hydration of cement are x-ray diffraction as shown in Figure 4 (NS), Figure 5 (N) and Figure 6 (O) below. Figure 4. Hydration products of cement (NS-35) Figure 5. Hydration Product of Cement (N-35) Figure 6. Hydration Product of Cement (O-35) ② The heat of hydration reaction The difference between the curve of the heat of hydration and the rate of heat of hydration of cement using three different gypsum cannot be recognized. Figure 7 below shows the hydration curves of cement using three different types of gypsum. As shown in the above physical performance experiment, it was confirmed that the phosphate refined gypsum for cement produced by the method of the present invention has the same quality as that of the cement phosphate refined gypsum prepared by the conventional firing and assembling method.

As shown in the above physical performance experiment, it was confirmed that the phosphate refined gypsum for cement produced by the method of the present invention has the same quality as that of the cement phosphate refined gypsum prepared by the conventional firing and assembling method.

Claims (2)

Alkaline material is added to Busan phosphate gypsum, which is produced in the half-water and gypsum phosphate manufacturing process, to neutralize the hydrogen ion concentration of phosphate gypsum from neutral to alkaline, and then the vapor pressure of 3-5 kg / ㎠ and the vapor pressure A method for producing a phosphate tablet for cement, characterized in that the soluble phosphate content is eluted to a saturation temperature of 140 ° C. and purified by three times insoluble phosphate. delete