KR101161755B1 - Method enhancing the grade of limestone - Google Patents

Abstract

PURPOSE: A dignity improvement method of low dignity limestone and the limestone are provided to manufacture cement raw material and fat lime stone through a series of processes including fracturing/crushing, calcinations, crushing, classification, disintegration, refinement etc. CONSTITUTION: A dignity improvement method of low dignity limestone comprises the following steps: pulverizing raw limestone into particle sizes of 200 mesh which is for enhancing calcination speed; manufacturing quick lime by calcinating the pulverized limestone; liberating useful material(CaO) from insoluble materials(SiO2, Al2O3) by pulverizing the calcinated material of limestone step by step; enhancing dignity of quick lime(CaO) by dry classifying the separated calcinated materials; manufacturing slaked lime and other hydrate by reacting tailing which is created in a dry classification step with water; liberating slaked lime and impurities which are contained in the hydrates; and increasing dignity of slaked lime by wet classifying and wet screening the disintegrated materials.

Description

Quality improvement method of low grade limestone and its limestone {METHOD ENHANCING THE GRADE OF LIMESTONE}

Limestone generally refers to the form of limestone with a high content of carbonate minerals. Limestone is a non-cracked sedimentary rock formed in the sedimentary basin, usually containing more than 50% of carbonate deposits of biological origin. Carbonate deposits are solidified and transferred to limestone due to the effects of the catalysis that is inevitably encountered during the sedimentation process. Thus, limestone is produced in the form of limestone and surrogate that can be developed by hatching, phase transition, and recrystallization due to the effects of secondary property alteration, hydrothermal alteration, and metamorphism.

Pure limestone (CaCO ₃ ) is theoretically present in three isoforms of calcite, aragonite, and vaterite, with 56% calcium oxide (CaO) and 44% CO ₂ . Although the chemical formulas of these limestones are very simple, chemical analysis shows that they contain significant trace elements, and differ in the type and amount of elements substituted for each mineral. In addition to the impurities contained in the calcite crystals, limestone also contains quartz, magnetite, pyrite, wollastonite, amphibole group, apatite, dolomite, dolomite, Limestone is not only CaO but also contains Al ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ , K ₂ O, Na ₂ O because it is accompanied by various insoluble minerals such as feldspar, muscovite and chlorite. It can only contain impurities.

   In the past, limestone has been used primarily for building materials and lime. However, in recent years, as the steel, cement, chemical, and environmental industries are developed, the use of limestone is diversified, and its use is increasing, which is increasing in importance, and the consumption of limestone is used as a measure of the industrial scale of the country.

Limestone is buried about 10 billion tons in Korea and is the most abundant mineral among domestic nonmetal minerals. Limestone production in 2009 is 8,163 million tons, of which 6,278 million tons are used as cement raw materials, accounting for 77% of domestic limestone consumption. In particular, limestone has excellent crushability and powder property, and is widely used in the form of finely pulverized calcium carbonate. Also, limestone calcined quicklime (CaO) and calcined calcined calcined [Ca (OH) ₂ ] steel It is widely used in chemicals, construction, agriculture and environment.

   Domestic limestone has been selectively mined mainly in high-grade limestone in the open air until recently, and the reserves of high-grade limestone have decreased, and as the mining of limestone ore moves from the outcrop to the deeper, the content of impurity minerals and colored minerals increases, which lowers the quality of limestone. It is a situation. As some cement companies are unable to match the composition of cement raw materials with only low-grade limestone, high-quality limestone is separately mined or purchased and mixed with low-grade limestone to secure the quality of cement clinker, thereby increasing the cost burden for cement raw materials. .

  Therefore, in the present invention, as the manufacturing industry has recently developed, it is intended to propose a method for improving the quality of limestone that can supply raw materials that meet various requirements of high-grade limestone and lime products.

Conventional Patent Application No. 1994-7350 (Publication No. 95-28821, Dry Purification Method of Calcite) is used to dry sieving after selectively crushing by using the difference of crushed strength of calcite and impurities contained in high-grade limestone ore. Patent has been registered to improve the quality of calcite by removing the impurities of granulation by the oil and magnetic lines, and by removing the impurity contained in the fine product among the sieve products by dry classification. This method simply crushes the limestone ore and selects it by the physical characteristics of the calcite (CaCO ₃ ) crystals and impurities (quartz and other coarse minerals) that make up the limestone.

However, the present invention is as shown in FIG. 5 and FIG. Precalcination of limestone ore to make calcite (CaCO ₃ ) crystals into quicklime (CaO) results in the formation of quicklime with a higher specific surface area than calcite crystals and lower hardness and strength than calcite at appropriate calcining temperatures and times. In addition, since the firing temperature is increased, the SiO ₂ component, which is an impurity, reacts with CaO to form a clinker compound, and thus the difference in the grindability between these quicklime (or clinker minerals) and impurity materials can be used.

In the present invention, a combination of a crusher such as a hammer mill, impact mill, jet mill, ball mill, and the like is separated by a single separation without excessive crushing, and then separated by a single substance. The use of a dry classifier (or sieving) can economically improve the quality of limestone in large quantities. The tailings of low CaO and high SiO ₂ content in the screening process are reacted with water (hydrated) to make hydrated lime [Ca (OH) ₂ ]. It is changed to a constant fine calcination. When the mixture of these slaked lime and impurities is separated into a wet pulverization method and then separated by wet sifting or wet classification using the particle size difference of the constituents, the quality of the slaked lime can be further enhanced.

   Therefore, the present invention is different from the existing invention in which only the limestone ore is purified in terms of enhancing the quality of the CaO component in the calcined product of the limestone and the hydrate of the calcined product.

Domestic limestone has recently been mining high-grade limestone mainly in the open air, and the reserves of high-grade limestone have decreased, and as the mining volume of limestone ore moves from the outcrop to the deeper, the content of impurities and colored minerals increases and the quality of the limestone is lowered. to be. Some domestic cement manufacturers are difficult to match the composition ratio of cement raw materials with only low-grade limestone, so the quality of cement clinker is secured by mining or purchasing high-grade limestone separately and mixing it with low-grade limestone. In the past, a combination of specific gravity screening, floating screening, and high-grade magnetic screening techniques were used to purify limestone. However, this method uses wet screening for limestone ore, which makes the screening process complex and expensive. low. Therefore, it is difficult to improve the quality of the limestone and the raw material of lime suitable for the use in accordance with the trend of high-grade limestone and lime products.

In the present invention, limestone is first calcined to change to quicklime. In addition, by using the difference in the crushability of the calcined materials, the useful materials and insoluble materials are separated by a combination of mills and then sorted dry. Low-quality screening products in dry selection react with water to change quicklime into hydrated lime, and then use limestone refining technology to take advantage of the physical, chemical, and physical and chemical properties of the materials produced in these dry and wet processes. to be. This method requires a separate sorting facility because limestone must be calcined into limestone and made into fine powder in order to use limestone as a cement raw material, but it does not consume large amounts of energy required for calcination and grinding when used as cement raw material. have.

In addition to calcite, domestic limestone includes quartz, feldspar, sericite, magnetite or pyrite, chlorite, wollastonite, amphibole group, Various impurities such as apatite and graphite are mixed. The coarse minerals of these limestones differ in specific gravity, hardness, magnetic responsiveness, color, and surface characteristics. Therefore, the classification, specific gravity screening, magnetic screening, refinement using the mineral, physical, and physicochemical properties of these limestone If the beneficiation technology such as flotation is applied, it can secure the quality suitable for cement raw materials and quicklime, slaked lime and hard calcium carbonate used as fine powder.

The present invention calcined limestone ore in advance for low-grade limestone, which cannot be used as a cement raw material, to make calcite crystals into quicklime (CaO) and to keep impurities in their original state contained in limestone coarse minerals. In addition, if unavoidable, the coarse minerals of limestone are made of some clinker compounds, and then separated by combining the grinders using the difference in the grindability between the quicklime and impurity materials. The separated material is separated into quicklime and impurities by dry sifting or dry classification. And the quicklime that cannot be separated is reacted with water again to make hydrated lime [Ca (OH) ₂ ] so it changes to fine hydrated regardless of the size of quicklime crystals. In the wet classification method, impurities are removed using particle size differences between slaked lime and impurities.

In general, when limestone is used as the raw material for Portland cement, that is, the limestone quality as shown in [Table 1] must be satisfied. In other words, the amount of CaO contained in limestone should be at least 44% and the amount of SiO ₂ should be at least 15.0%. The lime saturation (LSD), silicic acid rate (SM), iron ratio (IM) and activity coefficient of the raw materials of portland cement The values can be adjusted so that the manufactured cement clinker can be used as a portland cement.

Most preferably, the limestone gemstone is 25 to 52% by weight of CaO, 5 to 40% by weight of SiO ₂ , 0.01 to 20% by weight of MgO, Al ₂ O ₃ It is to improve the quality of limestone for low quality limestone ore which is difficult to use as Portland cement raw material containing 0.01 to 15% by weight and 0.01 to 5% by weight of total alkali (Na ₂ O + 0.658K ₂ O).

In general, in the case of steel, steel, alloy carbide, or glass limestone, which are used in the form of mass as can be seen in the specifications of limestone and lime products, the grinding operation can be performed to separate limestone and impurity minerals into a single unit. The quality of these products is limited by the quality of the limestone ore. However, in the case of limestone products used in the form of fine powders such as cement raw materials, quicklime, slaked lime and hard calcium carbonate, the calcite crystals and the impurity minerals can be separated into groups by fine powdering through grinding.

   Therefore, applying the screening technology using the difference in physical and physicochemical properties of the separated rock minerals can produce limestone suitable for the quality of cement raw materials.

On the other hand, when quick lime or slaked lime can be used in the form of fine powder, the quicklime and various clinker minerals are formed as fine crystals according to the change in the calcining conditions of the limestone, and these minerals react with water to produce various hydrates. Therefore, the application of beneficiation technology using the difference in the physical, chemical and physical and chemical properties of the calcined products and the hydration products can improve the quality of these lime products. In other words, calcined materials produced by calcination of low grade, low grade, high grade limestone or limestone can be pulverized by dry to separate the constituents into group separation, so that the quality of limestone and quicklime can be greatly improved by dry selection. Can be. In addition, when the quicklime is reacted with water to make hydrated lime, or when the slaked lime is reacted with carbon dioxide to synthesize hard coal, a series of chemical reactions form materials that are essentially different from those of the limestone. As a result, in the case of calcining limestone to produce quicklime, hydrated lime and hard calcium carbonate (CaCO ₃ ), the difference in the physical, chemical and physicochemical properties of hydrated lime, hard coal and impurities can be newly exploited, thus providing more extensive beneficiation than conventional beneficiation. New methods can be applied to improve the quality of these lime products.

The effect that can be obtained by purifying low-grade limestone is that it does not need to selectively mine high-grade limestone, which saves the mining cost, enables the development of poor minerals, and increases the production of limestone. It can be used for a separate purpose. In addition, the following benefits can also be obtained when manufacturing cement clinker. That is, prior to the final grinding of limestone, since the granulated materials such as quartz and mica, which are not easily crushed and sintered, are removed in advance, the grinding ratio and firing ratio of the raw materials and the grinding ratio of the clinker can be saved. In addition, the purchase cost and transportation cost of high-grade limestone mixed with low-grade limestone can be saved. As the limestone quality increases, various kinds of cements can be produced with a single ore, and the strength of the cement can be increased because the clinker reaction is easy in the cement kiln.

    In the future, as the production of low-grade limestone increases due to deep mining, and the amount of high-grade limestone is increased, the economic burden of mining, transporting and purchasing high-grade limestone is expected to increase. Therefore, it is necessary to develop a refining technology that improves the quality of limestone to the point that the limestone mined in the limestone mine owned by the cement company can be used as a cement raw material. If the mass purification technology of limestone is developed in connection with the process of manufacturing cement clinker of cement company, it is possible to produce high quality cement raw materials, and to apply high quality quicklime and slaked lime and heavy and hard calcium carbonate. do.

1 is a flow chart to improve the quality of low-grade limestone according to the present invention.
Figure 2 is a schematic diagram showing a range of particle size industrialization possible by general beneficiation technology.
3 is an XRD analysis of low-grade limestone ore used in the present invention.
4 is a photograph of the flakes by type of low-grade limestone ore,
5 is a schematic diagram showing the pyrolysis process of calcite crystals according to the calcination temperature of calcite crystal when calcining limestone,
Figure 6 is the result of XRD analysis of the classification product according to the classification conditions when pulverized limestone or classified by dry classifier.
7 is an XRD analysis result of calcination produced according to calcination temperature of limestone ore,
8 is a result of XRD analysis of the product separated into a sieve after grinding the limestone calcined by a grinder,
9 is a result of XRD analysis of the product obtained by pulverizing the limestone calcined product by a pulverizer after changing the separation conditions of the dry classifier,
FIG. 10 is an XRD analysis result of a product classified by a wet classifier after hydration of a classification product that is not suitable for cement raw material quality when dry classification of limestone calcined product.
FIG. 11 is an XRD analysis result of the product overflowed (O / F) when classified with a wet classifier. FIG. 12 is a particle size analysis result of the product flowed through the classification using a wet classifier. FIG. 13 is a wet classification system. XRD analysis results of the product under flow (U / F) when classified with a classifier, Figure 14 is a particle size analysis results of the product under flow (U / F) when classified with a wet classifier.

Table 2 shows the results of chemical analysis of low-grade limestone produced in Danyang, Korea. The amount of CaO contained in limestone is 41.03% and the amount of SiO ₂ is 16.48%, which makes it difficult to use as a cement raw material. Therefore, such limestone is not used because it does not satisfy the quality of the limestone used as a combination raw material of Portland cement, and is left untreated in limestone mines.

Lime stone CaO 25 ~ 52 wt%, SiO ₂ 5 ~ 40 wt%, MgO 0.01 ~ 20 _{wt%, Al 2 O 3 0.01 ~} 15 _{wt%, Total alkali (Na 2 O} + 0.658K 2 O) 0.01 ~ 5 It is desirable to improve the quality of limestone for low-grade limestone ore which is difficult to use as a Portland cement raw material containing weight%.

 3 is a result of XRD analysis of the sample to determine the constituent minerals of limestone, Figure 5 is a schematic diagram showing the pyrolysis process of calcite crystals according to the calcination temperature of calcite crystal when calcining limestone, 4] shows a photograph taken with a polarized microscope made of limestone flakes. Quartz, pyrite, dolomite, etc. are observed as impurity minerals, calcite and impurity minerals exist in various crystal shapes and sizes, and the accompanying states of these coarse minerals are also very diverse.

Limestone is classified into four types of high quality, medium quality, low and medium quality, low quality, and the results of limestone composition, whiteness, and crystal size are shown in [Table 3]. The lower the limestone quality, the larger the size of calcite crystals, the lower the whiteness, and the higher the content of colored minerals, alkali components, and MgO. Quartz, which is a representative impurity mineral, is generally thicker than high-grade limestone crystals and can be easily removed by applying a washing process. However, the lower the limestone quality, the larger the limestone crystals and the smaller the quartz crystals, the more difficult it is to physically select using the difference in the grindability of these limestone coarse minerals. In addition, iron, which is a colored component, may exist as a component of impurity minerals in coarse minerals, but may be finely distributed in limestone matrix, so that whiteness is important for heavy and hard coal use. Physical removal of iron is very difficult.

In general, in the case of steel, steel, alloy carbide, or glass limestone, which are used in the form of mass as can be seen in the specifications of limestone and lime products, the grinding operation can be performed to separate limestone and impurity minerals into a single unit. The quality of these products is limited by the quality of the limestone ore. However, in the case of limestone products used in the form of fine powder, such as cement raw materials, calcite crystals and impurity minerals can be separated into groups by fine powdering through grinding. Therefore, applying the screening technology using the difference in physical and physicochemical properties of the separated rock minerals can produce a lime-based material suitable for the quality of cement raw materials.

   On the other hand, when quick lime or hydrated lime can be used in the form of fine powder, according to the change in the calcination conditions of limestone, quicklime and various clinker minerals are generated as fine crystals according to the calcination temperature as shown in [Table 4]. Reacts with water to produce various hydrates. Therefore, the application of beneficiation technology using the difference in physical, chemical, and physical and chemical properties of calcination products and hydration reaction products can improve the quality of these lime products.

The calcined material produced by the calcination of low grade, low grade, high grade limestone ore and limestone can be pulverized by dry to separate the constituents into groups, so that the quality of limestone and quicklime can be improved by dry selection. In addition, when the quicklime is reacted with water to make hydrated lime, or when the slaked lime is reacted with carbon dioxide to synthesize hard coal, a series of chemical reactions form materials that are essentially different from those of the limestone. As a result, in the case of calcining limestone for making quicklime, slaked lime and hard coal, it is possible to newly apply differences in the physical, chemical and physicochemical properties of slaked lime, hard coal and impurities so that a wider range of beneficiation methods can be applied. Therefore, the quality of these lime products can be sufficiently improved.

  Hereinafter, a method of manufacturing a high-grade lime-based material for low-grade limestone according to the present invention will be described.

  1 is a high-grade limestone manufacturing method and production for low-grade limestone

It is a process chart showing the process of recovering the product quicklime and slaked lime.

   During the high-grade lime process according to the present invention, the step of crushing and crushing the limestone ore into a particle size suitable for increasing the calcination speed;

   A calcination step of making limestone produced through the crushing and grinding steps into quicklime;

The calcined material produced in the calcining step of the limestone is combined and ground by an impact mill (hammer mill, impact mill, jet mill, etc.) and a ball mill (ball mill), and useful materials (CaO) and insoluble materials (SiO ₂ , Al ₂ O Liberation of ₃ );

   A sorting step of classifying the pulverized calcined product by dry cyclone to improve the quality of quicklime to remove impurities;

   Reacting the tailings generated in the sorting step with water to form hydrated lime and other hydrates;

   A pulverizing step of separating the slaked lime and impurities contained in the hydrate generated in the step of forming the hydrate into a single body;

   Purifying method for improving the quality of the low-grade limestone characterized in that consisting of; a wet screening step of removing impurities by wet sieving or wet classification of the material separated in the crushing step and the substances generated in these dry and wet processes Portland cement raw materials and quicklime, characterized in that utilized for the use of slaked lime.

In the step of calcining the limestone, using a separate calcination kiln or using heat generated when manufacturing the clinker in the cement kiln to save energy and reduce the amount of CO ₂ (g) is supplied to the hot gas (hot gas) Limestone is to be deoxidized to quicklime by separately feeding through the apparatus and calcining the limestone ore at least 5 to 60 minutes in the temperature range of 900 to 1,300 ° C.

  When calcining the limestone gemstone below 900 ℃ deoxidation is not made normally, if the calcining at 1,300 ℃ or more deoxidation in a form that is not suitable for use is preferably carbonized at a temperature of 1,000 ℃, within 5 minutes If calcining for more than 60 minutes without being made normally, it is desirable to decalcify the limestone into quicklime by calcining for 30 minutes because it is not economical.

In the step of pulverizing the deoxidized calcined product, a combination of a hammer mill, an impact mill, a pin mill, a jet mill, a ball mill, and the like, which is a grinder mainly using an impact force to separate the useful materials and the insoluble materials contained in the calcined material, is optionally useful. Grind material and insoluble matter. If the separation is not sufficient, it is crushed again and classified with a dry classifier, and the fine product is concentrated and the coarse product is recovered to the tailings. At this time, the recovered fine product (concentrate) is used for quicklime or as a raw material for slaked lime and cement. Substances that are difficult to use as cement raw materials for dry ships are reacted with water to change quicklime to hydrated particles, and then pulverized again to increase the screening efficiency, and the wet sieving method uses wet cyclone. Separate. At this time, the recovered fine concentrate is used as a raw material for Portland Cement or as a cement admixture, slaked lime and hard calcium carbonate raw material which can be used at higher value.

  Hereinafter will be described in detail through a preferred embodiment of the present invention.

   [ Example  One]

Table 5 shows the chemical composition ratio of limestone ore. The limestone contains about 41.03% CaO and 16.48% SiO ₂ , which makes it difficult to match the modulus of cement raw materials. As can be seen from the XRD analysis of the limestone ore of FIG. 3, the main constituent mineral is composed of calcite, dolomite, and quartz, and contains trace amounts of mucovite. have. The content of MgO, Al ₂ O ₃ , and total aikali was satisfied with the quality standards of the raw material of limestone, and it was shown that the removal of mainly free-quartz could improve the quality of limestone.

   FIG. 7 is an XRD analysis result of a product pulverized in a dry classifier after grinding limestone calcined product in an impact grinder, and calcined the limestone gemstone at 800 to 1,300 ° C. for 1 hour for XRD analysis. One result.

In general, pyrolysis starts at 600 ° C when the partial pressure of CO ₂ (g) is very low. However, calcining limestone can raise the partial pressure of CO ₂ (g) up to 1 atm under atmospheric pressure. At this time, the temperature at which limestone is pyrolyzed is about 900 ℃. Therefore, in order to industrially decarbonate the limestone, it must be maintained at least 900 ° C. As can be seen in Figure 7, when calcined limestone, the limestone is partially decarbonated at 800 ° C. The main constituent minerals are composed of calcite, quicklime (CaO), quartz (quartz, SiO ₂ ), and the like. However, the higher the calcining temperature, the higher the decarboxylation rate of the limestone, the higher the amount of quicklime produced. The amount of quartz reacted with quicklime decreased, and the amount of calcium silicate compound, a cement clinker compound, increased. When the firing temperature is increased to 1,300 ° C. or higher, all SiO ₂ components contained in limestone are changed into cement clinker minerals. Therefore, in order to increase the content of quicklime (CaO) contained in the concentrate in the refining process, by controlling the firing time according to the particle size and the firing temperature of the limestone, the firing temperature of limestone is rapidly changed within the range of 900 ~ 1300 ℃. It is desirable to increase the amount of production. In addition, as can be seen from the calcination reaction diagram of the limestone of Figure 6, when the crushed to separate the limestone raw material to the crushed Mohs hardness of the calcite is 3 and the Mohs hardness of quartz is about 7 It is anticipated that the relatively weak calcite will be finely ground than the relatively strong quartz and will be screened by dry classification or specific gravity screening. However, as shown in FIG. 4, since limestone is closely bonded with calcite crystals and impurity quartz crystals, limestone must be excessively pulverized in order to separate and interface with each other. As a result, the particle size of these constituent minerals becomes so small that it is difficult to implement a dry classification and sorting method which is relatively economical and can be processed in large quantities. Therefore, these materials are screened by a wet method such as the floating screening method invented. This method is capable of increasing the quality of limestone to a quality suitable for use as a cement raw material. As a result, the selection cost is high. And dehydration and drying are expensive and must solve environmental problems. However, the calcining of limestone makes it possible to artificially change the type of mineral phase rather than simply improve the quality of the limestone ore, thereby making use of the physical, physicochemical and chemical properties of the synthesized minerals.

   When the limestone ore is calcined at 900-1100 ° C. as shown in FIG. 7, the quartz contained in the limestone is maintained in its original state, and only calcite can be selectively made into quicklime (less than Moss hardness 3). As well as quartz, the hardness is much lower than that of calcite, so when properly combined with crushers, the quartz is not crushed well and only the quicklime is selectively finely powdered. Can produce raw materials.

  ( Example  2)

   [Table 6] shows the chemical composition of each product in which limestone is calcined at 1,000 ° C. sequentially by hammer mills (or impact mills, jet mills) and ball mills, which are impact mills. The results of the analysis are shown in terms of limestone, and [Fig. 8] shows the XRD analysis results of the calcined products according to the inlets.

As can be seen from the table, the smaller the grain size, the higher the CaO content and the SiO ₂ content. And the content of the alkali component was lowered, the quality of the limestone showed a tendency to increase. Only 200-mesh sieves were able to match the CaO and SiO ₂ grades suitable for cement, and the yield was about 41.3%. However, as can be seen in the commercially available particle size range according to the screening technology of [2] there is a limit to classify as a dry constitution.

  ( Example  3)

   [Table 7] and [Table 8] show the classification conditions of the dry cyclone classifier of the product obtained by grinding the limestone calcined at 1000 ℃ with hammer hammer mill as the impact grinder and grinding step by step with the jet mill. The chemical composition of the product obtained by the change is shown in terms of limestone. Figure 9 shows the XRD analysis of the product according to the classification conditions.

As can be seen in FIG. 9, the higher the rotational speed of the dry cyclone (the more the finely pulverized material), the higher the content of CaO and SiO ₂ And the content of the alkali component was lowered, the quality of CaO was higher, and the quality of SiO ₂ was lowered. In case of 7,000O / F product (D ₉₀ : 7.9㎛), CaO quality was increased by 51.3% and SiO ₂ content was very low up to 3.7%. As a result of classification at 3,000 rpm ((D ₉₀ : 43.9㎛)), the product of 3,000O / F was 47.9% of CaO and 10% of SiO ₂ , accounting for 58% of the total product. It is analyzed that the alkali component is 0.5% or less, and it can be used as cement raw material. However, the 3,000 U / F product was found to be unusable as a cement raw material because of its low CaO content of less than 30.9% and the high content of SiO ₂ above 35.7%.

  ( Example  4)

Table 9 shows that 23,00U / F ((D ₉₀ : 43.9㎛) classification products with less than 30.9% of CaO and more than 35.7% of SiO ₂ cannot be used as cement raw materials. After the calcination to make a calcination and wet separated by a single separation, the chemical composition of the product classified as a cyclosizer, a kind of wet cyclone converted to limestone form [Figure 10] XRD analysis results of these wet classification products Indicated.

As can be seen from Table 9, as a result of classification with a wet cyclosizer, the CaO content of the overflowed product (d ₉₀ : 20㎛) was 49.13% or more and SiO ₂ content was 2.34% or more. As shown in FIG. 11, hydrated lime and hydrated lime were partially carbonized to exist as calcite. At this time, since there is no diffraction line of f-SiO ₂ , it is determined that the SiO ₂ component is present in the form of cement hydrate. And their particle size was shown to have a fine particle size of 100㎛ or less as shown in FIG. Therefore, they can be used as raw materials for cement and slaked lime or carbonized by carbonation.

XRD analysis results of wet classified products 1-5 stage (D ₉₀ : 51 μm) are shown in FIG. 13, and the results of particle size analysis are shown in FIG. 14. As a result of XRD analysis, the 1-5 stage products are mainly composed of cement clinker minerals 2CaO®SiO ₂ and melilinite and unreacted quartz (SiO ₂ ), so they are used as cement raw materials and admixtures, or belite (2CaO®SiO). ₂ ) It can be used as a raw material for cement production.

Claims (9)

Crushing and grinding the limestone ore into a particle size of 200mesh suitable for increasing the calcination speed;
Calcination step of making limestone produced through the crushing and grinding steps into quicklime;
Pulverizing the calcined material of the limestone stepwise to separate the useful materials (CaO) and insoluble materials (SiO ₂ , Al ₂ O ₃ ) into a single body;
A dry classification step of classifying the separated calcined products in a dry manner to remove impurities and increasing the quality of quicklime (CaO);
A hydration step of reacting the tailings generated in the dry classification step with water to form lime and other hydrates;
A disintegration step of separating the slaked lime and impurities contained in the hydrate generated in the hydration step into a single body;
The method for improving the quality of low-grade limestone, characterized in that consisting of; a wet screening step to increase the quality of the slaked lime by removing the impurities in the disintegration step by wet sieving and wet classification.
The method of claim 1, wherein the limestone gemstone is 25 to 52% by weight of CaO, 5 to 40% by weight of SiO ₂ , 0.01 to 20% by weight of MgO, Al ₂ O ₃ It is characterized by improving the quality of limestone for low-grade limestone ore that is difficult to use as a Portland cement raw material containing 0.01 to 15% by weight and 0.01 to 5% by weight of total alkali (Na ₂ O + 0.658K ₂ O). How to improve the quality of low-grade limestone. The method of claim 1, wherein the separate calcining kiln in the step of calcining limestone
In cement kilns to utilize or save energy and reduce CO ₂ (g) emissions.
The heat generated from the manufacture of the linker and insufficient heat source can be
The method for improving the quality of low-grade limestone, characterized in that the limestone gemstone is calcined for at least 5 to 60 minutes in the temperature range of 900 ~ 1,300 ℃. The method of claim 1, wherein the pulverizing step of separating into pieces is characterized in that the useful and insoluble materials are separated by combining a hammer mill, an impact mill, a pin mill, a jet mill, and a ball mill to prevent excessive pulverization of the calcined product of limestone. The elegance improvement method of the low grade limestone made with. 5. The method for improving the quality of low-grade limestone according to claim 4, wherein the product separated from each other is pulverized and classified by a dry classifier to improve the quality of the calcined material so that it can be used as a raw material for producing a Portland cement clinker. The low-grade limestone quality improvement method according to claim 4, wherein the quicklime and clinker compounds contained in the calcined product of the limestone are converted into hydrates. The low-grade limestone quality improvement method according to claim 6, wherein the hydrate of the calcined product is pulverized by wet separation. 7. The low-grade limestone quality improvement method according to claim 6, wherein the CaO quality of the hydrate is improved by wet classification of the separated hydrate. Limestone prepared according to any one of claims 1 to 8.

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