The soul of craftsman strengthens mining
Dig more stones (about 100). After upgrading, you can dig coal, aluminum and copper< br />
heavy hammer crusher is an indispensable coarse crushing equipment in limestone crushing proction line, which can crush materials no larger than 1800mm
the shaping hammer crusher is comparable to the sand making machine. It is mainly used to reshape the coarse broken materials. It is a limestone crusher with crushing + shaping two and one
jaw crusher is an indispensable equipment in limestone crushing, which is mainly used as coarse crushing equipment. In the sand proction line, it is responsible for high-quality crushing, while in the grinding proction line, it is necessary to crush the materials to qualified grinding particles. Limestone jaw crusher is a kind of widely used limestone crusher with simple structure, low cost, large swing angle, low suspension, short liner and large crushing ratio
the impact crusher is mainly used in the proction of sand and stone aggregate, for the generation and shaping of limestone coarse aggregate. In a conventional limestone gravel proction line, there are usually impact crushers. The impact crusher smashes the material by hammering and rebounding the impact plate. The crushing efficiency is high and the particle shape is good
the cone crusher is also used in the crushing of limestone, whether it is hard limestone or soft limestone, it can retract and release freely. The advantage of using cone crusher as limestone crushing equipment is less st and fine powder content, which is more suitable for manufacturers who do not need mineral powder. The disadvantage is that in addition to the HPT multi cylinder hydraulic cone broken, the rest of the cone broken are not flattering, need to join the shaping machine part. This kind of limestone crusher is suitable for some high-end users with economic strength, and can greatly release the proction efficiency
both impact crusher and sand making machine are fine crushing equipment of limestone, which have excellent shaping ability, so they can be applied to shaping of limestone coarse aggregate. Of course, if you are an idealist, there is no wrong choice. However, the impact crusher and sand making machine are still widely used in limestone sand making
the roller crusher is a kind of double rod crusher, which can crush the material through the extrusion of two toothed rollers and the splitting of roller teeth, and can be used in the crushing of limestone. This kind of limestone crusher can be used as coarse crushing equipment or medium and fine crushing equipment. The distance and tooth shape of roller can be selected by oneself.
Asphalt hypothesis.
the asphalt hypothesis is an early hypothesis. The asphalt hypothesis holds that the asphaltene in coal is the main material for bonding between coal particles. The softening point of asphalt is 70 ℃～ 80 ℃. In the process of compression molding, e to the relative displacement between coal particles, the heat generated by mutual pushing and friction makes asphaltene soften into a cohesive plastic material, The lignite contains free humic acid, which is a kind of colloid with strong polarity. In the process of briquetting, the external force makes the coal particles contact closely, According to the capillary hypothesis, there are a lot of pores containing water in lignite. During the briquetting, the pores are crushed, and the water is squeezed out, which covers the surface of the coal particles to form a water film, and then fills the gaps between the coal particles, showing the intermolecular force of interaction, According to the colloid hypothesis, lignite is composed of solid phase and liquid phase, and the solid phase is composed of many tiny colloidal humic acid particles with particle size of 1 μ During the molding process, the colloidal particles are concentrated to form briquette with certain strength.
molecular adhesion hypothesis.
molecular adhesion hypothesis was put forward by naumovich, The above hypotheses only explain some phenomena in the briquetting process from one aspect, and need to be further explored.
the briquetting mechanism of other coals without binder
the experimental results of anthracite briquetting, The wet bonding mechanism and dry bonding mechanism of instrial briquette without binder are analyzed.
the wet bonding mechanism of briquette is analyzed.
the main reason why the crushed coal is pressed in the wet state is that there is a certain degree of bonding between the coal particles, During the drying process of briquette, the surface tension of liquid membrane water increases and the forces of coal particles are closer to each other, The van der Waals force between coal molecules increases. Until the liquid film evaporates dry, the van der Waals force between coal molecules reaches the maximum. In addition, the friction resistance between dry coal particles is large, and the coal particles are inlaid with each other to proce large mechanical meshing force. Therefore, the dry briquette is mainly formed by the van der Waals force between coal molecules and the mechanical meshing force between coal particles It is found that coking coal has the best briquetting performance, with compact and smooth surface, high compressive strength and good waterproof performance; Anthracite has the worst briquetting performance, low briquette quality and low compressive strength. This is e to the low microhardness of coking coal and the high microhardness of anthracite. Soft coal is easy to be crushed in the briquetting process, resulting in finer pulverized coal filling into the coal particle gap, achieving the most compact accumulation, making the briquette dense and smooth, High compressive strength.
the briquetting mechanism of pulverized coal with binder
the briquetting of pulverized coal with binder refers to the process of briquetting coal under a certain pressure after the pulverized coal is fully mixed with the additional binder; The binder is coal tar, tar pitch, petroleum asphalt (also known as petroleum resie) or water-soluble binder. The briquette is pulverized coal of - 3mm (more than 95%), which is similar to sand. From the point of view of thermodynamics, the briquetting process of pulverized coal is a non spontaneous process of entropy rection of the system, The choice of binder is not only related to the quality and cost of briquette, but also the restricting factor of briquette instrialization. Therefore, the key to study the briquette forming mechanism is to explore the interaction between coal and binder, that is, the type, size and influencing factors of the force To realize the instrialization of briquette, and even provide theoretical basis for powder forming related fields (including metallurgy, chemical instry, building materials, medicine, etc.) There are few researches on briquetting mechanism.
wetting and bridging
wetting and bonding between coal particles and binder directly affect the quality of briquette, The viscosity of asphalt determines the cold compressive strength of briquette; The thermal stability of briquette is determined by the amount of coking components in asphalt. When asphalt is formed with low volatile coal, the coking components form the framework of asphalt coke in the briquette structure, which makes the briquette have good thermal stability. In order to obtain the most suitable viscosity of asphalt binder, the former Soviet Union scholars studied the important properties of asphalt, There are two stages in which the viscosity of asphalt changes significantly. One is the transition from solid state to plastic state; The other is the transition from liquid state to high flow state. Asphalt is solid at room temperature. Only when the temperature is 20 ℃～ 25 ℃ higher than its softening point, can it be mixed with coal particles evenly and fully soaked. The former Soviet Union scholars used a special particle polishing technology to study the mixture of coal and asphalt binder through microscope observation, The results show that the binder before molding should be in plastic state and have good expansibility, and the binder in briquette should be solidified as soon as possible to form a skeleton structure that can bear the mechanical force, If the structural strength of the briquette is lower than that of the skeleton formed by the binder, the crushing fineness of the briquette will be increased to increase the total surface area of the briquette, The strength of briquettes depends on the structural strength of materials.
the results of the study on the main technological conditions of lignite briquetting show that the interaction process between coal particles and binder is very complex, including wetting, mass transfer, bonding and other processes, The strength of briquette is the result of mechanical bonding e to the penetration of binder into the coal particle space, dehydration and solidification. In the process of dehydration, hardening and consolidation of binder, briquette shrinks with the evaporation of water, the distance between particles decreases, and the crushing resistance increases, The strength of briquette increases.
the minimum contact angle and the maximum bonding work
the compressive strength of briquette quantificationally characterizes the force between coal and binder, that is, the wetting degree between coal and binder. Theoretical analysis shows that the prerequisite for the bonding between binder and coal particle is that the binder moistens the surface of coal particle. The wetting degree can be expressed by contact angle and bonding work, The contact angle between briquette and binder and the surface tension of liquid binder were measured by cd-a Concord contact angle meter and CBVD Concord surface tension meter; The contact angle between coal and water increases, the degree of coal wetting by water decreases, and the compressive strength of briquette decreases, that is, the force between coal and binder decreases, It is found that both the surface and the pores of the coal particles are composed of gelatin and various crystals formed by hydration of the binder. The gel and crystal are surrounded by coal particles and interconnected to form a crystal network, so that the coal particles are firmly bonded together to form briquette. The more the gel is in the briquette, the more the rod, columnar and needle like crystals grow, the more evenly distributed. The lower the strength of briquette, the higher the briquette strength.
study on the low-temperature consolidation mechanism of iron concentrate with binder, it is considered that the low-temperature consolidation is the result of the joint action of adhesion and cohesion between binder and briquetting material; Cohesive force refers to the intermolecular attraction of binder or block material itself. When there is binder, the wetting effect of binder on the particle surface makes the material particles change from solid-solid contact to liquid-solid contact. Therefore, low temperature consolidation is essentially a phenomenon of solid-liquid interface The results show that the strength of the agglomerates is not only related to the intermolecular force (i.e. van der Waals force) and the mechanical force caused by the surface roughness of the agglomerates, but also related to the electrostatic force and the chemical bond force.
the strength of the agglomerates is determined by the surface wetting heat, surface electricity and infrared spectros, The interaction mechanism between binder and iron ore surface and the mechanism of green pellet strength have been studied; It is proposed that the strength of green pellets of magnetite powder with binder depends on the chemical energy, viscous energy, capillary gravitational energy, van der Waals gravitational energy, electrostatic energy and magnetic gravitational energy, and is mainly determined by chemical energy, viscous energy and capillary gravitational energy, which enriches and develops the strength theory of green pellets.
The activity index of mineral powder refers to that mineral powder and cement are mixed in the ratio of 1:1, standard specimens are made according to the cement mortar molding method, and cured according to the standard method, and standard specimens of cement are also made, and cured according to the standard method. Their strength was measured at the age of 7 days and 28 days
the activity index is the ratio of the same age strength of the specimens with mineral powder and cement. S95 means that the 28d activity index reaches 95% or more, that is, the ratio of mortar strength with 50% mineral powder to mortar strength without mineral powder is not less than 95%
ground ore powder is ground water quenched blast furnace slag powder, also known as slag powder. In order to adapt to the addition of slag in cement and concrete, GB / t18046-2008 stipulates granulated blast furnace slag powder
that is, the granulated blast furnace slag in accordance with the GB / t203 standard can reach a considerable specific surface area and meet the corresponding activity index after drying and grinding (or grinding with a small amount of gypsum). Ground mineral powder is a kind of high quality admixture for preparing high performance cement and concrete