Application of metal powder materials in the pharmaceutical industry
Solid pharmaceutical preparations account for about 70% to 80% of pharmaceutical products. The dosage forms containing solid pharmaceuticals include powders, granules, capsules, tablets, powder injections, and suspensions, such as the ibuprofen we used to cure the new crown disease Sustained-release capsules, ibuprofen suspensions, Ganmao granules, etc., are actually closely related to powder materials. The production processes involved include crushing, grading, mixing, granulation, etc. Some solid pharmaceutical preparations need to be modified during the preparation process to improve the powder properties, so as to meet the needs of product quality and powder operation. In addition to the above-mentioned solid pharmaceutical preparations which need to be crushed and processed, the preparation of some raw materials also needs to rely on the catalytic reduction of metal powders.
The application of metal powders in medicine also involves different shape control. Among them, spherical powders are mostly prepared by liquid phase and gas phase methods, and flake powders are mostly prepared by solid phase methods. The particle size, purity and mass fraction of trace elements of metal powder play a decisive role in the yield and pass rate of medicine. The development and application of powder preparation technology and metal powder materials are important to the preparation process and preparation quality of the pharmaceutical industry. influences.
In traditional Chinese medicine preparations and synthetic medicines, traditional Chinese medicine biological powder materials and metal powders have been widely used. At present, for mineral medicines, precious medicines and traditional Chinese medicines with special properties, hammering and ball milling methods are generally used in China. Make the drug reach a certain particle size, and can maintain the inherent pharmacodynamic basic substance of traditional Chinese medicine.
The particle size, quality difference, mixing uniformity, and tablet strength of traditional Chinese medicine are mostly related to the powder. For the medicinal materials processed by ultrafine powder technology, the fluidity, filling and compression molding properties of the solid preparation can be controlled. To achieve the purpose of controlling the quality of solid preparations, and its disintegration, dissolution and bioavailability are related to the powder properties of each material in the drug prescription.
The smaller the particle size of the powder material for traditional Chinese medicine, the better. The powder material of traditional Chinese medicine with a median particle size of about 15 μm has a high cell wall breaking rate, which is beneficial to the release and absorption of the drug; During the process, the homogenization of each active ingredient is conducive to retaining biologically active ingredients and improving the efficacy of the drug; it is easy to shape and apply, which is conducive to exerting the efficacy of the drug and improving the utilization rate of the drug.
When synthesizing western medicine, metal powder materials with a median particle size of about 75 μm are generally used for chemical reactions such as catalysis, reduction and oxidation. In recent years, with the current upsurge of modernization of Chinese and Western medicine and the development of nanotechnology, powder technology also has a broader development space, which provides new methods and approaches for the research of modern drug delivery systems, and also significantly improves the human body’s ability to respond to various diseases. Components Absorption rate and absorption capacity of active ingredients.
As an important industry in the field of fine chemicals, medicine has become the focus of development and competition in the past ten years. The synthesis of modern medicine depends on the production of new and high-quality pharmaceutical intermediates, so more and more people pay attention to powder technology and powder materials; Put forward higher and newer requirements. Among metal powder materials, zinc powder is most widely used in medicine because of its preparation process, physical and chemical properties, good catalytic reduction effect on pharmaceutical intermediates or synthetic drugs, and high product yield. With the increasing safety and environmental protection requirements, powder technology and powder materials will continue to develop, and the development of new alternative technologies and materials has always been promoting the continuous progress of the pharmaceutical industry.
Application of jet pulverization equipment in the production of titanium dioxide
1. The principle of jet crushing
Jet milling equipment includes jet mill, jet mill or fluid energy mill, which uses the energy of high-speed airflow or superheated steam to make particles impact, collide, and rub against each other to achieve ultrafine pulverization or depolymerization. The general principle of jet milling: the dry and oil-free compressed air or superheated steam is accelerated into a supersonic airflow through the Laval nozzle, and the high-speed jet ejected drives the material to move at a high speed, causing the particles to collide and rub against each other and be crushed. The crushed materials arrive at the classification area with the airflow, and the materials that meet the fineness requirements are finally collected by the classifier, and the materials that do not meet the requirements are returned to the crushing chamber to continue crushing.
2. Classification of jet milling equipment
The jet mills used in industry mainly include the following types: flat jet mill, fluidized bed jet jet mill, circulating tube jet mill, counter jet jet mill, and target jet mill. Among these types of jet mills, flat jet mills, fluidized bed jet mills, and circulating tube jet mills are widely used.
2.1 Counter jet jet mill
After the material enters the crushing chamber through the screw feeder, the impact energy of the high-speed airflow is sprayed out by several relatively set nozzles, and the rapid expansion of the airflow forms the collision and friction generated by the suspension and boiling of the fluidized bed to crush the material. Coarse and fine mixed powder is driven by the negative pressure airflow through the turbine classification device installed on the top. The fine powder is forced to pass through the classification device and is collected by the cyclone collector and bag filter. The coarse powder is thrown away by gravity and the centrifugal force generated by the high-speed rotating classification device. It goes to the four walls and settles back to the crushing chamber to continue crushing.
2.2 Flat jet mill
The high-pressure airflow as the crushing kinetic energy enters the pressure-stabilized air storage bag on the periphery of the crushing chamber as an air distribution station. The airflow is accelerated into a supersonic airflow through the Laval nozzle and then enters the crushing chamber, and the material is accelerated into the crushing chamber through the Venturi nozzle. Perform simultaneous crushing. Since the Laval nozzle and the crushing chamber are installed at an acute angle, the high-speed jet stream drives the material to circulate in the crushing chamber, and the particles collide, collide, and rub against each other as well as with the wall of the fixed target plate to be crushed. Driven by the centripetal airflow, the fine particles are introduced into the central outlet pipe of the pulverizer and enter the cyclone separator for collection, while the coarse powder is thrown to the surrounding wall of the pulverization chamber under the action of centrifugal force for circular motion and continues pulverization.
2.3 Circulating tube jet mill
The raw material is fed into the crushing chamber through the Venturi nozzle, and the high-pressure air is sprayed into the runway-shaped circulating tubular crushing chamber with unequal diameter and variable curvature through a group of nozzles, accelerating the particles to collide, collide, rub and crush each other. At the same time, the swirling flow also drives the crushed particles upwards into the classification area along the pipeline, and the dense material flow is shunted under the action of the centrifugal force field in the classification area, and the fine particles are discharged after being classified by the louver type inertial classifier in the inner layer. Coarse particles return along the downpipe in the outer layer and continue to be pulverized in a circular manner.
2.4 Fluidized bed jet mill
Jet mill (fluidized bed jet mill) is the compressed air that is accelerated by the Laval nozzle into a supersonic airflow and then injected into the crushing area to make the material fluidized (the airflow expands to form a fluidized bed that suspends and boils and collides with each other). Therefore every particle has the same motion state. In the pulverization zone, the accelerated particles collide with each other and pulverize at the junction of each nozzle. The crushed material is conveyed to the classification area by the updraft, and the fine powder meeting the particle size requirement is screened out by the classifying wheels arranged horizontally, and the coarse powder not meeting the particle size requirement is returned to the crushing area for further crushing. Qualified fine powder enters the high-efficiency cyclone separator with the airflow to be collected, and the dusty gas is filtered and purified by the dust collector and then discharged into the atmosphere.
Application of jet pulverization equipment in the production of titanium dioxide
1. Titanium dioxide requirements for crushing
Titanium dioxide used as a pigment has excellent optical properties and stable chemical properties. Titanium dioxide has very high requirements on particle size, particle size distribution and purity. Generally, the particle size of titanium dioxide is based on the wavelength range of visible light, that is, 0.15m ~ 0.35m. And as a white basic pigment, it is very sensitive to the increase of impurities, especially iron impurities, and the increase is required to be less than 5 ppm when pulverized. In addition, titanium dioxide is also required to have good dispersibility in different coating systems. Therefore, the general mechanical crushing equipment is difficult to meet the requirements, so the final crushing of titanium dioxide (finished product crushing), at present, jet mills are used at home and abroad.
2. The choice of jet mill for titanium dioxide production
According to the crushing requirements of titanium dioxide: narrow particle size distribution, less increase in inclusions, good dispersibility, etc., and the material characteristics of titanium dioxide: high viscosity, poor fluidity, fine particle size and easy wall attachment, etc., currently titanium dioxide manufacturers all choose self-grading function The flat (also known as horizontal disc) airflow mill is used as the final crushing equipment for titanium dioxide;
And use superheated steam as crushing tool. Because the steam is easy to get and cheap, the pressure of the steam working medium is much higher than that of the compressed air and it is also easy to increase, so the kinetic energy of the steam is larger than that of the compressed air. At the same time, the cleanliness of superheated steam is higher than that of compressed air, with low viscosity and no static electricity. Moreover, while crushing, it can eliminate the static electricity generated by material collision and friction, and reduce the secondary cohesion of powdered materials. In addition, crushing at high temperature can improve the application dispersibility of titanium dioxide and increase the fluidity of titanium dioxide. The energy consumption of superheated steam is low, which is only 30% to 65% of that of compressed air.
3. Development of jet milling
With the rapid development of titanium dioxide industry, the requirements for equipment are getting higher and higher. On the premise of meeting the process conditions and quality requirements, the large-scale and systematization of equipment is particularly important, and jet milling is also constantly improving along with the development of titanium dioxide. The production capacity of the gas powder machine has also changed from the initial 1.2t/h to 1.5 t/h to 2.5 t/h to 3.5 t/h now, and the production capacity of the gas powder system has also changed from 10,000 t/h for a single line a. Up to now, the single line is 20,000 t/a, and the collection method has also changed from the relatively backward wet collection to the advanced dry collection, which greatly improves the primary yield and reduces waste.
Learn more about the benefits of fluidized bed jet mills
Since the advent of jet milling and grading equipment in the 1930s, the types have been continuously updated and the structure has been continuously improved. Bed (on-spray) jet mill, etc.
The fluidized bed jet mill is a new model developed and put into use by a German company in the late 1970s and early 1980s. It has the characteristics of low energy consumption, light wear, low pollution, low noise, fine particle size and relatively uniform distribution of products, etc. Resins, phenolic resins, PVC, pigments and dyes, powder coatings, couplers, pharmaceuticals, cosmetics, advanced ceramics, magnetic powders, abrasives, metal powders, food, fragrances, stearic acid, fats, waxes, mineral powders, and pesticides and wettability It is widely used in the production of powder and so on.
Main Advantage
(1) Change the line and surface impact crushing of the traditional jet mill to the three-dimensional impact crushing of the space, and make full use of the high-speed airflow generated by the jet impact in the flow of materials in the crushing chamber, so that the crushing area is similar to a fluidized state Excellent gas-solid crushing and graded circulation flow effect, which improves the efficiency of impact crushing and the comprehensive utilization of energy. Compared with other traditional methods, the energy consumption is reduced by 30-40% on average;
(2) Since the impact crushing area and the gas-solid flow belt are placed in the middle space of the crushing chamber, the impact and abrasion of the materials driven by the high-speed airflow on the wall of the crushing chamber are avoided, and the most serious wear problem in jet impact crushing is improved, and greatly reduced. the potential for the material to be contaminated;
(3) Protective gases such as high-purity nitrogen or argon are used as the working medium to prevent oxidation, and the closed-loop operation has low gas consumption and reduces costs;
(4) There is no dust flying during the complete closed-loop operation, no pollution to the environment, and no harm to the human body;
(5) After jet milling, the activity of the powder increases. The energy of the high-speed jet flow in the jet mill crushing and classification process can not only cause the particles to be impacted and crushed, but also change the internal structure of the particles, especially the surface state, to a certain extent. The energy of the gas flow removes atoms or ions from the particle lattice, causing a mechanical loss of the crystalline structure. In this way, while the powder material is ultrafinely pulverized, the surface energy or internal energy of the particles increases, and the activity of the particles increases. The increase in the activity of the particles is not only beneficial to the chemical reaction, but also beneficial to the adsorption and coating of the particles.
(6) The particle size of the product is fine, the output is large, and it is suitable for large-scale production; the particle size classification accuracy is high, so the particle size distribution of the product is narrow, and the particle size of the product is also easy to adjust.
The fluidized bed jet mill has many advantages such as low energy consumption, small wear and high classification accuracy, and it is widely used in the current ultrafine grinding equipment. However, because there is no specific theoretical guidance, engineering practice is often used to design the structure of the fluidized bed jet mill.
People have done a lot of research on the nozzle, but the research on the flow field inside the fluidized bed jet mill is still limited to theoretical analysis. There are many applications for the pulverization of fluidized bed jet mills, but in the process of jet milling, they often rely on experience to adjust process parameters, lacking the support and guidance of theoretical research.
Therefore, it is necessary to further deepen the applied basic research of the fluidized bed jet mill jet milling process, and strengthen the understanding and knowledge of the fluidized bed jet mill pulverization mechanism. With the continuous development of fluidized bed jet mill pulverization technology and the widening of its application range, fluidized bed jet mill pulverization technology will play an increasingly important role.
Main beneficiation and purification technologies and characteristics of kaolin
The purpose of purifying kaolin is to remove harmful dyeing impurities such as iron minerals, titanium minerals and organic matter to improve the whiteness of the product; on the other hand, to remove sandy minerals such as quartz and feldspar to improve Improve the quality of kaolin products, and then expand the breadth and depth of its application, and obtain better economic benefits while making full use of kaolin resources.
At present, the purification process of kaolin mainly includes gravity separation, magnetic separation, flotation, leaching, chemical bleaching and roasting.
1. Re-election
The gravity separation purification process mainly uses the difference in density and particle size between kaolin and gangue minerals to remove light organic matter and high-density impurities containing elements such as iron, titanium and manganese, so as to achieve the purpose of purifying kaolin and reduce or remove impurities. Negative impact on its whiteness.
2. Magnetic separation
The magnetic separation process is used to remove weak magnetic dyeing impurities such as hematite, siderite, pyrite and rutile in kaolin. Magnetic separation does not require the use of chemicals and has no pollution to the environment, so it is widely used in the purification process of non-metallic ores. The removal of weakly magnetic impurity particles in kaolin requires a high magnetic induction intensity and magnetic field gradient, and the development of magnetic separation technology and equipment upgrades have enabled the magnetic separation and purification of kaolin and other non-metallic minerals to be effectively realized.
3. Flotation
The flotation purification process can effectively remove iron, titanium and carbon impurities in kaolin, and realize the recovery and reuse of low-grade kaolin resources such as coal series kaolin. Kaolin has finer particles and is more difficult to float than gangue minerals. Therefore, reverse flotation is often used in the kaolin flotation purification process to achieve a better effect of removing impurities, such as reverse flotation carbon removal, desulfurization and iron removal. Kerosene is used as a collector, pine oil is used as a foaming agent, and water glass is used as an inhibitor. The flotation purification process is mostly used to treat kaolin raw ore with more impurities and lower whiteness, so as to realize the comprehensive utilization of low-grade kaolin resources.
4. Leaching
Leaching is a method of selectively dissolving and removing certain impurity components in kaolin through appropriate leaching agents, such as acid leaching and microbial leaching using hydrochloric acid or sulfuric acid. The leaching process is simple, energy-saving, can reduce production costs, and has good development potential. Using sulfuric acid with a concentration of 25% to acid-leach hard kaolin with high iron content for 5 hours, the iron removal rate can reach 37.67%. Because most of the iron in the raw ore exists in the form of pyrite, in order to achieve a better iron removal effect, oxidative acid leaching is carried out with H2O2 as the oxidizing agent. Coal series kaolin contains impurities such as pyrite, limonite and hematite. During the calcination process, pyrite will be oxidized into dark brown iron oxides, which will reduce the whiteness of kaolin. Thiobacillus ferrooxidans can decompose pyrite through catalytic oxidation, so it can be used to remove pyrite from kaolin.
5. Chemical bleaching
Ferric ions and their oxides are the main dyeing impurities that reduce the whiteness of kaolin. The method of removing these harmful impurities through chemical reagents is called chemical bleaching. The chemical bleaching method of kaolin is divided into oxidation method, reduction method and oxidation-reduction combined method.
The principle of the oxidation bleaching method is to oxidize the harmful coloring impurities in the reduced state into soluble substances, and then remove them. For example, oxidize pyrite into soluble ferrous sulfate, and then oxidize the organic matter and remove it by washing with water. Commonly used strong oxidants include sodium hypochlorite, potassium permanganate and hydrogen peroxide. The bleaching effect is affected by pH value, temperature, chemical dosage, pulp concentration and bleaching time.
The principle of the reduction bleaching method is to reduce the insoluble ferric oxide to soluble ferrous salt, so that the harmful element iron is converted into a soluble phase for dissolution, and then removed through the washing process. Commonly used reductive bleaching agents include sodium dithionite (Na2S2O4) and thiourea dioxide (HO2SC(NH)NH2).
6. Roasting
Roasting is also an important purification process to improve the whiteness of kaolin. Kaolin can remove carbon-containing impurities in it through roasting process, such as removing magnetic impurities through magnetization roasting and magnetic separation, and removing certain metal impurities through chlorination roasting.
Low-temperature roasting can remove surface and interlayer hydroxyl groups without destroying the kaolinite structure, and at the same time effectively decompose carbon-containing organic matter, so that the low-grade coal-measure kaolin can meet the requirements of glass fiber raw materials, and effectively realize the low-grade coal-measure kaolin resources. use.
Magnetization roasting converts iron-containing impurities in kaolin into strong magnetic or strong magnetic iron-containing minerals, and then removes impurities by magnetic separation. The purification effect of magnetization roasting on kaolin is better than that of traditional chemical bleaching methods.
Chlorination roasting is the addition of chlorinating agents during kaolin roasting to convert certain metal oxides and sulfide impurities into volatile chlorides to achieve the purpose of removing the metal elements.
7. Combined purification technology
It is difficult to obtain high-quality kaolin products by a single purification process, especially when dealing with low-grade coal-measure kaolin with large reserves in my country and kaolin with complex mineral composition. Different types of kaolin treatment processes are different, among which soft kaolin treatment process includes crushing, pulping, cyclone, selective flocculation, bleaching, centrifugation, peeling, magnetic separation; hard kaolin treatment process includes crushing, pulping, Cyclone, centrifuge, flaking, bleaching or crushing, roasting, pulping, cyclone, flaking, centrifuge; sandy kaolin treatment process includes pulping, spiral classifier, sedimentation, centrifuge, flaking, bleaching or raw ore , Pulping, Gravity Desanding, Blending, Flotation.
8. Stripping
Peeling is divided into mechanical peeling and chemical peeling, which is an important process of deep processing technology. It is necessary to peel kaolin into extremely thin sheets, and then go through magnetic separation to remove iron and bleach to meet the requirements of low wear and high whiteness. It is widely used in papermaking, Cosmetics, medicine, etc.
5 types of electronic communication function filling materials and market demand
Electronic communication functional filler is a kind of functional filler with excellent performance. It is filled in the packaging materials of electronic chips and electronic printed circuit boards. It can meet the signal transmission requirements of high frequency, high speed, low delay, low loss and high reliability. It is widely used In electronics, advanced communications (5G), storage computing, artificial intelligence, autonomous driving, satellite positioning, aerospace, high-speed railway and other fields.
1. Common filling materials for electronic communication functions
At present, the mature electronic communication functional filling materials on the market mainly include high-performance silica powder materials, spherical alumina materials and boehmite, high-performance silica powder materials include high-purity silica, crystalline silica , spherical silica and fused silica.
(1) High-purity silica
It is made of natural quartz sand through processes such as airflow crushing, surface coating, and impurity removal. It has the characteristics of high purity and concentrated particle size distribution, and can reduce the release of α particles from packaging materials, thereby reducing the occurrence of integrated circuits. The probability of soft errors is filled in epoxy molding compound as a functional filling material, and is widely used in chip packaging in the fields of electronic communication, storage computing, and artificial intelligence.
(2) Crystalline silica
Using natural quartz sand as raw material, it is processed through impurity removal, grading, airflow crushing and other processes. It has the characteristics of concentrated particle size distribution, precise control of large particles, and less magnetic foreign matter. It can improve the performance of downstream related products in terms of electrical properties and other aspects. Physical properties, silicone rubber products prepared from it as raw materials can be used as composite materials in electronic communications, aerospace, high-speed railways, LED lighting and other fields.
(3) Fused silica
It is made of crystalline silica as raw material through high-temperature melting, jet milling and other processes. It has the characteristics of low electrical conductivity, excellent insulation performance, and low magnetic foreign matter. At the same time, the dielectric constant, dielectric loss, and linear expansion coefficient are also high. Lower than crystalline silica, it is used as a functional filler in high-frequency and high-speed copper clad laminates in the fields of advanced communications (5G), autonomous driving, and artificial intelligence.
(4) Spherical silica
It is made of high-purity silica powder material through spheroidization treatment, jet milling and other processes. It has uniform particle size, high spheroidization rate, high fluidity, good insulation performance, low magnetic foreign matter, low dielectric A series of excellent characteristics such as electrical constant, low dielectric loss, and small linear expansion coefficient are mainly used as functional filling materials for high-frequency and high-speed copper clad laminates, as well as functional filling materials for epoxy molding compounds in chip packaging materials, etc., used in aerospace, high-speed High-frequency high-speed copper clad laminates and high-end chip materials for high-end railways.
(5) spherical alumina
Alumina is used as raw material, and it is prepared through airflow crushing, spherification, surface coating, impurity removal and other processes. It has easy dispersibility, controllable particle size and uniform particle size, high spheroidization rate, low content of magnetic foreign matter, It has the characteristics of good thermal conductivity and high volume filling rate. It is mainly used as a filling material in epoxy resin and silicone to produce thermal interface materials.
The Effect of Sugar Substances on the Crystallization of Nano-CaCO3
Nano-calcium carbonate is an important new nano-material, which is widely used in coatings, rubber, paper and other fields. The preparation of different types of nano-calcium carbonate particles has always been the focus of research.
At present, metal salts, organic acids, inorganic acids, polyvinyl alcohol, amino acids, and surfactants are often used as crystal form control agents for nano-calcium carbonate. By using different crystal form control agents, different sizes, shapes, and crystal forms can be obtained. Nano-calcium carbonate particles, and can change the agglomeration of nano-calcium carbonate particles, so as to realize the controllable synthesis of nano-calcium carbonate.
Nano-calcium carbonate was synthesized by carbonization method, and glucose, sucrose and soluble starch were used as crystal form control agents respectively. The influence of the addition of non-crystal form control agents and different sugar substances on the conductivity and pH changes during the reaction process was analyzed in detail. the result shows:
(1) By adding sucrose, glucose, and soluble starch with the same mass fraction to the reaction system, relatively regular cubic calcite-type nano-calcium carbonate crystals were obtained, which may be due to the existence of polar —OH groups in the sugar structure, Moreover, O in the molecule has a lone pair of electrons, which has high electronegativity, and can coordinate with Ca2+ through charge matching, which inhibits the growth of nano-calcium carbonate crystals.
(2) Adding sugar additives before the carbonization reaction can promote the nucleation reaction, reduce the surface energy of calcium carbonate crystal nuclei, enable smaller crystal nuclei to exist stably, inhibit the aggregation and growth of calcium carbonate crystal nuclei, and generate cubic nano calcium carbonate particles.
(3) The carbonization process is controlled by using sugar as a crystal form control agent, and the obtained product has relatively good dispersibility.
Material Application of Tourmaline Mineral
Tourmaline mineral material is a material with special functions that is processed and prepared from natural tourmaline mineral as the main raw material. Tourmaline mineral materials mainly include ultrafine tourmaline powder and modified ultrafine tourmaline powder, as well as tourmaline ceramics, tourmaline fibers, tourmaline coatings, and tourmaline composites prepared from ultrafine tourmaline powder or modified ultrafine tourmaline powder. materials etc.
Tourmaline gems are mainly dominated by attributes such as aesthetics, durability, rarity, and non-toxicity, while tourmaline mineral materials mainly emphasize their functional attributes, such as spontaneous polarization, pyroelectricity, infrared radiation, and adsorption properties. Tourmaline mineral material is a functional material obtained by reprocessing tourmaline mineral according to human will in order to realize some functional application properties of tourmaline.
1. Water treatment materials
The spontaneous polarization of tourmaline makes it have an electrostatic field around it, and has strong adsorption, which can effectively adsorb metal ions and acid radical ions in the solution, and crystallize from the surface of tourmaline, thereby purifying water. Therefore, tourmaline is a good environmental material for water pollution control, and as an excellent raw material for preparing adsorbents, it has a very good application prospect.
Because it is difficult for metal ions to enter the crystal structure of tourmaline, the adsorption of tourmaline to ions is mainly surface adsorption. There is an electrostatic field around tourmaline particles, and its surface adsorption is mainly complex adsorption and electrostatic adsorption, and can simultaneously adsorb anions and cations, and the adsorption amount is not limited by the ion exchange amount. In the solution, positive and negative ions are gathered at the two poles of the tourmaline crystal, and the ions are precipitated after reaching the saturated adsorption concentration.
2. Health care textiles
The number of negative oxygen ions in the air is one of the important criteria for evaluating air quality, because negative oxygen ions can reduce the content of dust and harmful gases in the air. Water in the air can be electrolyzed by tourmaline, thereby increasing the number of negative oxygen ions in the air. In addition, tourmaline can produce infrared radiation absorbed by the human body, produce thermal effects, increase the temperature of local tissues of the human body, expand blood vessels, accelerate blood flow, improve local blood circulation, and play a role in health care and physical therapy. Therefore, tourmaline can be used in textile manufacturing to make clothing and accessories with health care functions.
In the 1990s, Japan began to use tourmaline as the main raw material to produce negative ion textiles, and used post-finishing technology to carry out negative ion modification treatment on natural fibers (such as cotton and wool). The treatment solution containing ultra-fine tourmaline powder is fixed and attached to the surface of the fabric by padding and drying processes, so that the fabric has anion function. The felt is modified with negative ions by using the treatment solution prepared by 5-15 μm tourmaline powder, anionic dispersant, binder and water, and the treated felt has a good negative ion generating effect.
3. Coating additives
Tourmaline mineral materials can be used as additives in negative ion coatings. Coatings added with ultrafine tourmaline powder can meet the requirements of general coatings on color perception, texture and scrub resistance, and can also release a certain concentration of negative ions to achieve a certain sterilization effect. Some negative ion coatings produced in Japan and South Korea have been sold domestically, and their prices are much higher than ordinary coatings.
4. Photocatalytic materials
TiO2 is a highly active photocatalytic material with good thermal stability and strong photooxidation resistance. However, the recombination rate of photoelectrons and holes produced by TiO2 is high, and the photocatalytic efficiency is low, which affects the industrial application of TiO2. Tourmaline has the properties of spontaneous polarization and infrared radiation, and the composite material of tourmaline and TiO2 can not only improve the photocatalytic activity of TiO2, but also have the advantages of both materials.
5. Fuel activation
Tourmaline has a high infrared radiation emissivity in the 3-6.2μm band, which is conducive to the absorption of radiation by the human body and produces thermal effects, so tourmaline mineral materials have health care and physiotherapy functions. At the same time, the excellent infrared radiation performance of tourmaline mineral materials can also be used to improve fuel combustion efficiency.
Fuel oil is a liquid mixture composed of a series of alkanes, olefins, naphthenes, aromatic hydrocarbons, polycyclic aromatic hydrocarbons and additives. The study found that the C-C bond resonance in fuel oil can absorb radiation with a wavelength of 3.2-3.6 μm, and the C=C and C≡C bonds absorb radiation with a wavelength of 4.4-4.7 μm and 5.8-6.2 μm, respectively. When the fuel molecule is activated by the infrared radiation material, it absorbs the radiation released by the infrared radiation material and stores the energy inside the fuel molecule. When the fuel enters the combustion chamber, the stored energy will be released in the form of explosive kinetic energy, thereby increasing the internal energy of the fuel molecules, so only a small amount of heat energy can be provided during combustion to break the carbon-carbon covalent bonds in the fuel molecules, thereby improving combustion efficiency and improved power performance.
Tourmaline mineral materials have a high infrared radiation rate in the 3-6.2μm band, so using tourmaline mineral materials to activate fuel oil can improve the energy-saving and emission-reduction effects of fuel vehicles.
Three Typical Processes and Applicable Objects of Powder Surface Modification
The surface modification process varies according to the surface modification method, equipment and powder preparation method. At present, the surface modification processes used in industry mainly include three categories: dry process, wet process, and composite process.
1. Dry process
This is the most widely used non-metallic mineral powder surface modification process. At present, for non-metallic mineral fillers and pigments, such as heavy calcium carbonate and light calcium carbonate, kaolin and calcined kaolin, talc, wollastonite, silica micropowder, glass microspheres, aluminum hydroxide and light magnesia, clay, ceramic pigments etc., most of them adopt dry surface modification process. The reason is that the dry method has the characteristics of simple process, flexible operation, low investment and good applicability of modifiers.
(1) Intermittent dry process
The characteristic is that the time of surface modification (that is, the residence time) can be flexibly adjusted in a wide range, but it is difficult to coat the particle surface modifier uniformly, the unit product consumes more chemicals, the production efficiency is low, and the labor intensity is high. Dust pollution, difficult to adapt to large-scale industrial production, generally used in small-scale production.
(2) Continuous modification process
It is characterized by better dispersion of powder and surface modifier, more uniform particle surface coating, less modifier consumption per unit product, low labor intensity, high production efficiency, and is suitable for large-scale industrial production. The continuous dry surface modification process is often placed after the dry powder preparation process to continuously produce various non-metallic mineral active powders in large quantities, especially for inorganic materials used in polymer-based composite materials such as plastics, rubber, and adhesives. Fillers and pigments.
2. Wet process
Compared with the dry process, it has the characteristics of good surface modifier dispersion and uniform surface coating, but it needs subsequent dehydration (filtration and drying) operations. It is generally used for water-soluble or hydrolyzable organic surface modifiers and occasions where the front stage is wet powder (including wet mechanical ultrafine pulverization and chemical powder) process and the latter stage needs to be dry, such as light calcium carbonate (especially It is the surface modification of nano calcium carbonate), wet finely ground heavy calcium carbonate, ultra-fine aluminum hydroxide and magnesium hydroxide, ultra-fine silicon dioxide, etc., because the slurry generated after the chemical reaction is not wet The method surface modification also needs to be filtered and dried, and the surface modified before filtering and drying can also prevent the material from forming hard agglomerates after drying and improve its dispersibility.
Inorganic precipitation coating modification is also a wet modification process. It includes pulping, hydrolysis, precipitation reaction and subsequent washing, dehydration, calcination or roasting and other procedures or processes.
3. Composite process
(1) Mechanochemistry/Chemical Coating Composite Modification Process
It is a process of adding a surface modifier during the action of mechanical force or fine grinding and ultrafine grinding, and chemically coating and modifying the surface of the particles while reducing the particle size of the powder. The characteristic of this composite surface modification process is that it can simplify the process, and some surface modifiers also have a certain degree of grinding aid effect, which can improve the crushing efficiency to a certain extent.
The disadvantage is that the temperature is not easy to control; in addition, since the particles are continuously pulverized during the modification process, a new surface is generated, and the particle coating is difficult to be uniform. It is necessary to design the addition method of the surface modifier to ensure uniform coating and higher In addition, if the heat dissipation of the crushing equipment is not good, the local excessive temperature rise during the strong mechanical force may decompose part of the surface modifier or destroy the molecular structure.
(2) Inorganic precipitation reaction/chemical coating composite modification process
After the precipitation reaction modification, the surface chemical coating modification is essentially an inorganic/organic composite modification process. This composite modification process has been widely used in the surface modification of composite titanium dioxide, that is, on the basis of precipitation coating SiO2 or Al2O3 film, titanate, silane and other organic surface modifiers are used to treat TiO2/SiO2 or Al2O3 The surface of composite particles is modified by organic coating.
(3) Physical coating/chemical coating composite modification process
The process of surface organic chemical modification after physical coating of particles, such as metal coating or coating.
New ultra-fine powder materials, nano-calcium carbonate has great development potential
Nano-calcium carbonate, also known as ultra-fine calcium carbonate and ultra-fine calcium carbonate, belongs to a new type of ultra-fine solid powder material. Nano-calcium carbonate has the advantages of fine particle size, high whiteness, good compatibility, and good optical properties.
Nano calcium carbonate is used in a wide range of fields, including paper industry, medical and health care, rubber products, coatings and plastics. Nano-calcium carbonate accounts for a large proportion in the plastics market and can be used as a plastic regulator and reinforcing agent. Nano-calcium carbonate has excellent dispersibility, can improve the anti-aging and impact strength of plastics, and is widely used in PVC film materials.
my country's nano-calcium carbonate industry started in the 1980s and entered the stage of industrial production in the late 1980s. Non-freezing method, multi-stage spray carbonization method, intermittent carbonization method, high gravity method, internal circulation carbonization tower preparation method, jet absorption method, etc. are the main preparation methods of nano calcium carbonate in my country. The batch carbonization method can be subdivided into two types: the intermittent stirring carbonization method and the intermittent bubbling carbonization method. At present, the intermittent bubbling carbonization method is the most widely used preparation method in the world. In recent years, with the efforts of leading enterprises, some nano-calcium carbonate production technologies in my country have reached the advanced level overseas.
The raw material of nano-calcium carbonate is limestone. my country is the country with the most abundant limestone resource reserves in the world, accounting for nearly 70.0% of the world's total reserves. my country's limestone resources are concentrated in Shandong, Anhui, Henan, Hebei, Shaanxi, Gansu and other places.
But at present, functional nano-scale calcium carbonate is far from meeting market demand. Different users have different requirements for products, not only depending on particle size, but also product performance and quality. At present, there are not only calcium carbonate with various particle sizes, but also various types of calcium carbonate. There are 50-60 varieties of calcium carbonate with various functions. For example, OT calcium, which is specially used for ink, still occupies the high-end ink market in China, which is worth pondering. Researchers and manufacturers engaged in nano-scale materials should work hard on the application performance of nano-scale inorganic powder materials to develop functional and special nano-scale inorganic functional materials.
Calcination-fluorine-free and nitric acid leaching to remove impurities from quartz sand
Pickling is an important means to remove impurities in quartz, commonly used are hydrofluoric acid, nitric acid, hydrochloric acid, sulfuric acid, acetic acid and oxalic acid. When using inorganic acids for acid leaching, due to the hardness of quartz sand, the concentration of these inorganic strong acids must be very high. In many cases, the concentration of the acid is between 20-30%, and the high concentration of acid will corrode the leaching equipment. Very strong.
The commonly used organic weak acid is oxalic acid, or a combination of some weak acids is used to improve the leaching efficiency. Acetic acid is also another organic acid leaching agent, which is completely non-toxic to the environment and basically has no loss to the target product SiO2. By adding oxalic acid and acetic acid, the impurity elements in the quartz sand can be effectively removed. In contrast, oxalic acid had higher leaching and removal rates for Fe, Al, and Mg, whereas acetic acid was more efficient in removing impurity elements Ca, K, and Na.
After calcination of quartz silicon ore in a certain place, oxalic acid, acetic acid, and sulfuric acid, which is easy to treat waste liquid in the later stage, were used as leachate to remove impurities from quartz sand. The results showed that:
(1) The total amount of impurities in the quartz ore selected for the test is 514.82ppm, of which the main impurity elements are Al, Fe, Ca, Na, and the impurity minerals are mica, nepheline and iron oxides.
(2) When the quartz silica ore is calcined at 900°C for 5 hours, the removal rate of pickling impurities is the highest. Compared with uncalcined quartz ore, the surface of calcined water-quenched quartz ore has more cracks with larger width and depth, and some holes of different sizes are distributed on the surface. This is because when calcined at 573°C, quartz will undergo a phase transition from α lattice to β lattice, and the quartz matrix will expand due to the change of lattice, and the expansion rate is about 4.5%, and the volume expansion will be lead to cracks. The cracks mainly occur at the interface between the quartz matrix and the impurity inclusions, where there are many impurities. It can be inferred that the quartz ore can produce cracks after calcination and water quenching, and the cracks will expose the impurities inside the quartz sand. , can promote the effect of impurity removal by acid leaching.
(3) The calcined quartz sand is acid-leached with 0.6mol/L oxalic acid, 08mol/L acetic acid and 0.6mol/L sulfuric acid at 80°C, with a solid-to-liquid ratio of 1:5 and a stirring speed of 300r/min. Time 4h is the best condition for leaching the quartz sand. Under the optimal conditions, the best removal rates of Al, Fe, Ca and Na are 68.18%, 85.44%, 52.62% and 47.80%, respectively.