Discussion on production technology and application of perlite in China

First, the distribution of resources

Perlite is acidic when one kind of glassy volcanic lava under certain conditions, is a non-metallic minerals, the main ingredient is SO _2, AI ₂ O _3, CaO, and a content of the compound crystal water, after artificial pulverized, The ore sand granules of a certain particle size are formed by fractional processing. Under instantaneous high temperature, the crystallization water vaporization inside the ore sand produces an expansion force, and the perlite ore particles in the molten state are instantaneously expanded, and after cooling, porous white particles are formed, and the physical and chemical properties are very high. Stable, with good thermal insulation performance, it is a good inorganic lightweight insulation material, which can be widely used in industries such as industry, agriculture, chemical industry, building materials, food processing and filtration. The mineral resources are mainly distributed in Henan, Hebei, Inner Mongolia, Liaoning, Shanxi, Fujian, Guangdong, Lancang, Hunan, etc., with Henan Xinyang, Hebei Chengde, Inner Mongolia Chifeng, Liaoning Jianping, and Shanxi Lingqiu as the source of the ore. Well, at the same time, some areas are accompanied by symbiotic non-metallic minerals such as Heiyayan, rosinite , vermiculite , zeolite , bentonite, etc., which are rich in resources and are valuable assets of China's geology and mineral resources.

Second, mining and processing

Since the 1960s, China has developed and utilized perlite mineral resources. Mining resources have been in a relatively primitive and backward stage for decades. Most of them are labor-intensive mining, and the utilization rate of mineral resources is extremely low. The quality of the post-sand grade is poor (rather than the low grade of the ore), resulting in a large amount of non-renewable resources wasted. The products and applications in the later stage have been in a single state (including standard requirements) for decades, and the added value is very low. With the development of science and the demand of the market economy, it has improved in recent years, especially from the source management of mines and the comprehensive mining of mines. The degree of mechanization and the classification of ore sand have been greatly improved. At present, some places in China have implemented uniform standards. Mining and making full use of waste for comprehensive development. In particular, the entry of foreign-funded enterprises, the advanced technology and equipment into the mining and processing, greatly improved the utilization of mineral resources, while improving the grade of mineral sand, providing high-quality raw materials for post-processing, such as the foreign company Esby, after Drying and selecting subdivisions, the grade of ore sand is very high, which is conducive to deep processing of later products. The selection and classification of ore sand into finished ore sand will become the development trend of scientific and rational exploitation and utilization of pearlite minerals in China in the future. At present, several new mining sites have been selected, including the use of fine powder. It has been treated as waste material, and has been developed and utilized in fine-diameter granules such as expanded and expanded vitrified beads, abrasives, filter aids, and spherical closed-cell perlite, effectively improving resource utilization and added value of later products, and reducing integration. Cost, benefit the country and the people.

Third, the production process technology

The expansion technology of perlite has been plagued by two problems of high energy consumption and pollution in China for decades. In the traditional production process, the preheating dehydration process generally adopts two forms of external preheating or internal preheating. The furnace type is horizontal preheating. External preheater for preheating a combustion of coal in preheated cylinder block outside manual control, preheating in a preheating cylinder is used with an internal mechanical conveying coal combustion preheater, both have advantages and disadvantages, mostly not very stable Controlling the content of crystallization water inside the ore sand and affecting the later puffing is also an important process technology that is most neglected in our expanded perlite industry and should be paid attention to. The expansion furnace is mainly divided into two types: horizontal furnace and vertical furnace. The heating forms are gas, fuel, lump coal, coal powder, gas and electric energy, respectively. The various energy consumptions are closely related to the furnace structure. The relationship also has a direct impact on the quality and cost of the product. At present, the energy efficiency of the hyperbolic expansion furnace in China is relatively good. From the internal analysis of the furnace, the general furnace is 600-800mm, and the annual output can reach more than 100,000 cubic meters. Other furnaces The type also has an annual output of 30,000-60,000 cubic meters. Different furnace types have a certain relationship with energy utilization. Incomplete combustion and full combustion are the key to energy consumption. We have many furnace designs that are not scientific enough. The waste is too large, the process temperature is not easy to control, the labor intensity is large, the environment is poor, and the production cost is increased, and the product quality is unstable. At present, China's waste heat utilization is still relatively backward. Some manufacturers have used a part of it. The use of waste heat to supplement oxygen supply and preheating of ore sand can improve the sufficiency of fuel combustion. Manufacturers can test it, foreign fuel, gas and oxygen supply. The wind makes full use of the waste heat to warm up, and the energy saving effect is very good.

At present, China's expanded perlite encounters three major problems in the production process, one is the furnace, the second is dust pollution, and the third is the low expansion ratio. In essence, this is a system technology problem, due to many manufacturers of perlite. The physical and chemical properties and production process points are not very clear, and the process balance conversion is also less aware. Only the general operating experience is used to maintain the traditional production process, and the quality control points in the production process are not taken seriously, including metering and feeding. Furnace and dust pollution are normal, and the expansion ratio is determined by the ore. In fact, the furnace, dust, and expansion ratio are low. Although it is related to the ore and furnace structure and expansion temperature, the same furnace type, the same temperature, The same ore sand, some furnace phenomenon and dust is less, manufacturers often pin their hopes on the burner, from the preheating to the temperature zone of the puffing furnace, all by the naked eye, intuitive feeling, the actual temperature is not accurate, This is not comprehensive. Let us think about why the perlite ore will expand. What is its expansion force, expansion time, and expansion temperature depending on the particle size? According to the physical and chemical properties of China's perlite, the general preheating dehydration temperature of the ore is 380-470 ° C, the expansion temperature is 1050-1150 ° C, and the melting temperature is 1200-1300 ° C. Then there is one dehydration, expansion and melt dissolution in this temperature zone. With time requirements, this requires a process balance parameter. The expansion force of crystallization water is directly related to the puffing quality of the product. Therefore, many of our manufacturers only pay attention to the expansion furnace and ignore the preheating furnace, which is extremely incorrect. At the same time, the uniformity of the particle size of the ore sand also has a great influence. In the same furnace production process, the furnace is fouled, the dust is large, and the puffing is not good. The key factors are the uniformity of the particle size of the ore and the balance of the preheating dewatering amount. The use of ore sand is used to minimize the dust of the ore, to improve the uniformity of the ore particle size, and to pay attention to the balance of preheating and dehydration. It is necessary to improve the product yield, reduce the production cost, and improve the resource utilization rate. The expansion factor is a parameter conversion. The reference object can be divided into raw ore and ore. Many people think that foreign countries can expand more than 40 times, while the domestic can only puff up more than 20 times. The actual is the same. The foreign puffed reference object is the ore. The density of the ore is generally 2.2 to 2.4, the bulk density of the ore is generally 1.2 to 1.4, and the bulk density of the perlite after expansion is 60 kg/m ³ , and the volume change is 2400 ÷ 60 = 40 (times), 1200 ÷ 60 =20 (times), if the ratio is the same, that is, the ratio is the same, we usually think that the production process can reach 16 to 18 times (for the ore volume), that is, the bulk density of the expansion powder is 50-60 kg/m ³ , It has been fully expanded, and the ore in all parts of China is basically achievable. If the bulk density of 1 ton of mineral sand is 60kg/m ³ and only 15-16 cubic meters, this means that a large amount of dust and ore impurities are generated during the production process, which reduces the volume of the material after puffing. Why do we need to improve the balance of ore grade and preheating dehydration? It is also one of the internal factors that reduce the overall cost and improve the performance of the product during the production process. The main way to solve the micro-powder in the production process is to improve the uniformity and pre-production of the ore. The balance of thermal dehydration reduces the source of micropowder production. At the same time, the collection process is collected by the decompression chamber during the cyclone collection and discharge process, reducing the wind pressure flow and temperature, and the appropriate water shower and bag filter collection can be solved when emptying. With China's environmental protection requirements, this is also the obligation that manufacturers should pay attention to and be responsible for social environmental protection, and it is also an essential requirement for modern factory production.

Fourth, application discussion

Due to the long-term development of China, the expanded perlite has always been subject to the JC/T209-92 standard. The performance quality (including the ore standard) is measured by the index of bulk density, which has certain certain scientific progress, social development and market demand. The quality standard gap, from a single thermal insulation performance requirement, to the filling application of light orthopedics and the application of industrial, agricultural, building materials, chemical and other fields, regardless of the quality standards of bulk density and particle size, At the same time, higher requirements are placed on the strength and water absorption of the pellets. Light weight is no longer the only measure of the quality of the products. The development of new technologies for inorganic lightweight insulation materials and the innovation of production equipment technology are our research. Important subject. The expanded vitrified microbeads developed by Beijing Huaweijia Technology Co., Ltd. are inorganic vitreous mineral materials processed by special production technology, which are irregular spheroid particles, internal porous cavity structure and surface glass. It is closed, smooth in gloss, stable in physical and chemical properties, and has excellent properties such as light weight, heat insulation, fire resistance, high and low temperature resistance, anti-aging, and low water absorption. It can replace fly ash floating beads, glass beads, expanded perlite, polystyrene. The application of many traditional lightweight aggregates such as granules in different products. It is an environmentally friendly high performance new inorganic lightweight insulation material. Can be widely used in industrial, agricultural, chemical, metallurgy, building materials and many other fields, from the main performance comparison of the following products, we can apply according to different physical and chemical properties.

According to the indicators mentioned in the table, the main application market of China's new energy-saving building materials is analyzed. The ordinary expanded perlite is used as the lightweight filler aggregate of new energy-saving building materials. It has many inevitable defects, and the water absorption rate is large. Powdering, resulting in large product shrinkage value, low strength, easy to absorb moisture and moisture, such as lightweight wall panels, decorative panels and thermal insulation mortar, especially in the application of thermal insulation mortar is very easy to cause hollow drum cracking, reduce overall performance, on civilian use In the case of industrial insulation, this problem is common. The expanded and expanded vitrified microbeads produced by the WH-III multi-stage silicon carbide electric heating tube type vitrification furnace have a good modification effect on the plate products, and the current lightweight refractory bricks (boards) and fire prevention on the market. Flame-retardant board and thermal insulation mortar are applied well, but the requirements for thermal conductivity are low, and the comprehensive performance of the product can not meet the requirements. The proportion of the mixture is large, and the thermal performance requirements are met. At the same time, the strength index can not meet the requirements. Performance will be out of balance, so the amount of light orthopedics added, there is a limit to increase the amount of product can meet the requirements of comprehensive product performance, light weight and strength are contradictory, we through scientific process design and equipment innovation, effective It solves the technical difficulties of light weight, low water absorption and other properties, and produces light-expanded vitrified microbeads with a bulk density of 50-80 kg/m ³ , which fills the domestic blank and expands at a particle size of 3-5 mm. In the production of vitrified microbeads, breakthroughs have been made in technology. We have utilized the excellent properties of expanded vitrified microbeads. We have developed a thermal insulation dry powder ready-mixed mortar that meets the requirements of China's building energy conservation. The expanded vitrified microbeads are used as lightweight aggregates for dry-mixed mortar, and pre-mixed in dry powder modification. Among the agents, a one-component inorganic dry powder insulation mortar is formed. The product has excellent thermal insulation performance, anti-aging and weather resistance, no air cracking, high strength, good adhesion and anti-sagging performance, insect ants are etched, and the burning performance is Grade A. The construction is convenient, and the on-site construction can be used with water and stirring, and can be directly applied to the dry wall.

The expanded vitrified microbead insulation mortar has excellent thermal insulation, heat insulation, fireproofing and construction performance, and compensates for many defects and deficiencies in other traditional thermal insulation mortars using polyphenylene granules and ordinary expanded perlite as lightweight aggregates, overcoming the expanded pearls. The rock has large water absorption and easy powdering. The volume loss rate is large in the slurry mixing, which is easy to cause the thermal insulation performance of the product to be lowered and the hollow drum cracking. At the same time, it can make up for the poor fire resistance of the polyphenylene granule organic material and the harmfulness of high temperature. Defects such as low gas and anti-aging weather resistance and high resilience during construction. A 2mm thick anti-cracking mortar with waterproof, impermeability and crack resistance is applied to the surface of the intumescent vitrified microbead insulation layer, and combined with the intumescent vitrified microbead insulation layer to form a heat preservation, crack resistance, fire prevention and resistance. A complete system that penetrates into one. The dry powder has a bulk density of 230-260kg and a thermal conductivity of 0.065. The performance indicators are superior to the relevant national industry standards and the performance of similar products in the market. The expanded vitrified microbead insulation mortar is an environmentally-friendly high-performance inorganic thermal insulation material. It is suitable for the internal and external wall composite insulation of various brick-concrete structures, frame structures and shear wall structures, and energy-saving projects for fire protection and thermal insulation of public facilities such as basement, garage, stairway corridor and fire exit. Expanded vitrified microspheres and expanded vitrified microbead insulation mortar

It has great market space and development prospects in the field of building energy-saving applications in China. According to the application research, for the performance requirements of my existing products, we roughly classify the expanded vitreous bead products and applications with different properties as follows:

V. Conclusion

The 21st century is an important period for the development of global environmental protection and energy-saving materials. Saving energy and protecting the environment is related to the survival of all mankind. The Chinese government attaches great importance to it. Policies and regulations for mandatory environmental protection and energy conservation have been introduced. Large and medium-sized cities and economically developed areas have taken the lead in implementing building energy conservation. Inorganic lightweight insulation materials, as one of the main lightweight aggregates for environmental protection and energy conservation, have been widely applied in the field of building energy conservation in China, and gradually evolved from single type to composite type. The comprehensive development and application of performance has great market demand, which provides a good business opportunity for our manufacturers engaged in energy-saving materials production. We must seize the opportunity to continuously improve product performance and improve resource utilization and added value with the spirit of scientific innovation. Focus on improving the performance of general-purpose products, develop high-performance products, and pay attention to the composite modification technology and application technology of materials, give full play to the unique performance of lightweight non-metallic inorganic environmental protection and energy-saving materials, and open up new application fields. Achieve better social and economic benefits.

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