The existing useful mineral beneficiation process ensures a high level of comprehensive utilization of resources. However, in order to further solve the problem of more rational utilization of natural resources, ecological protection, energy conservation and production control, this requires that the processing and mineral processing technologies and processes of ore and other resources need to reach a new level.
In order to further improve the processing of useful minerals, the following research results and the possibility of using them are analyzed.
First, the preparation process before the selection of useful minerals
(1) Quality assurance of selected mineral raw materials
The quality of the selected ore must meet the following conditions in order to maximize the efficiency of the mining company:
1. Process incompatible ores should be mined and processed separately. Mixing ore with different materials will reduce the beneficiation process indicators and technical and economic indicators. Therefore, most modern mining companies pre-classify the ore into 2 to 3 grades, and some enterprises are divided into 8 to 11 grades (such as Salto, Italy). Lili, Canada's Sur Liban concentrator, etc.);
2. Remove rock from coarse (broken) ore to reduce energy consumption in crushing, grinding and beneficiation;
3. Stabilize the content of useful ingredients and harmful impurities while maintaining the physical and mechanical properties of the ore similar to the specifications of each grade of ore designed.
According to the results of the geological process mapping of the deposit, the quality of the designed ore to be mined and the quality of the actually selected ore can be kept, so that:
(1) Organizing ore streams of the same composition;
(2) in the pre-selection according to the sorting component, according to the ore flow or by batch system, the discardable coarse tailings;
(3) Under the premise of the lowest energy consumption of the “blasting-crushing-grinding†system, the most suitable ore crushing process is adopted to obtain a final product with a certain particle size composition.
The above measures can be achieved when there are nuclear physical equipment for detecting ore raw material components, establishing a component radiation detecting station, and determining a sorting component.
(2) Softening of raw materials and selective dissociation of minerals
The rationality of pre-softening of raw materials depends on the high energy consumption of the grinding process (60%~70%). In the process of crushing and grinding, the selective dissociation of minerals directly determines the recovery rate of valuable components and the loss rate of minerals into the beneficiation tailings due to the overgrown minerals and the associated minerals and gangue minerals.
Now, by increasing the number of rotations of the crushing body (body and jaw), improving the shape of the crushing chamber, applying inertial transmissions, and applying high-energy low pulses to the material to be crushed, the working efficiency of the conventional crushing equipment has been improved. Ball mills and rods are improved by reducing the grain size of the mill, increasing the throughput, optimizing the rotational speed of the mill barrel, selecting a reasonable filling rate for a particular shape of the grinding media, and using chemical additives - material strength reducing agents. Grinding efficiency of the mill (30% to 70%).
The following methods can be used to increase the degree of dissociation of the recovered minerals with minimal grinding of the unit particles and gangue particles:
1. When the medium mine and the concentrate are re-ground, the ball mill is changed to a non-drop system;
2. In the closed-circuit grinding circuit, install flotation classifier, single-slot flotation machine, flotation jig, re-election equipment and flotation of hydrocyclone with coarse-grain flotation machine, so as to The useful minerals that are dissociated are recovered during the grinding process.
3. In the crushing and grinding circuit, high-efficiency screening and grading equipment are adopted.
According to the theory of Orowana-Grifitesa-Rabinjera-Levernifeva, the selective dissociation of minerals from the continuum should include the following stages: mineral lattice defects in the contact of continuum minerals Aggregation on the surface; due to this local agglomeration, tension and micro-cracks are formed; they are expanded and joined into large cracks, eventually causing surface damage. The probability of mineral dissociation along this surface of the continuum depends on the largest number of defects in this area due to differences in the lattice parameters of the contact minerals.
In order to effectively achieve the above stages, including the process of softening the mineral continuous interface, the following process principles should be followed:
(1) The deformation load should be a tensile or shear load. Depending on the physical properties of the mineral, the following methods can be used to achieve this principle:
When minerals have different elastic-plasticities, mechanical pulsating compression loads are often used (for example, squeezing materials in all directions on the working surface of the equipment, changing the pressure of surrounding liquid or gaseous medium, causing the nuggets to collide with each other multiple times or Colliding a hard surface, etc.);
The vibration or high-energy shock wave of different frequencies is used to act on the ore interface, so that the ore particles receiving different external action properties are subjected to tensile stress;
Heat treatment of minerals having different linear expansion coefficients (compression) and thermal anisotropy of volume expansion coefficient;
If the different components in the nugget or particles have selective absorption properties (electrostriction, magnetostriction, and electrical breakdown on the surface of the electrical conductor) for the vibration of the electromagnetic field, the ore is treated with an electric field or a magnetic field;
Using some of the special properties of minerals and the structural characteristics of different useful minerals, other methods are used to treat the ore.
(2) The power applied to the energy of each ore or pair of ore particles (regardless of the type of energy causing the deformation) should be well controlled so as to form microfacies only at the interface between the particles rather than within the crystal. Gap. For example, a small energy pulse is applied to the nugget multiple times to cause irreversible pressure to build up at the interparticle interface.
(3) The frequency and speed of the deformation should be high enough to reduce the energy loss caused by the elastic deformation of the material. At the same time, the speed of deformation should be determined, that is, under the action of elastic stress, the edge crack should be generated enough time to ensure the diffusion of its surface active material (Rabin Gera efficiency) and the mechanochemical effect of strengthening the micro-gap enlargement. Appearance.
The direct process of destroying pre-softened particles should also be achieved by following these guidelines:
1 The magnitude of the energy action should be higher than the energy pulse of the softening process, but not exceeding the limit at which the crystal itself begins to break;
2 In order to achieve high selective dissociation, the energy acting on the material should be gradually increased to discharge the dissociated particles from the process, because the strength of the interface between the particles in different nuggets varies within a specific range. ;
3 The energy density must be high to create the necessary stress density for each damaged particle. As with softening, it is preferable to use tensile and shear stresses or impact forces with pulse characteristics.
The reliability of the theory presented above has in principle been confirmed by many experimental results. These tests include oscillating, electromagnetic, pulsing, heat treatment and other high energy effects on the ore. The recommended, new, non-conventional comminution methods generally, in addition to increasing particle dissociation, form particles of more uniform particle size, increasing the effective power of the device and increasing the ability to create new surfaces.
Obviously, new liquid electric breakers and electric pulse crushers, air jet mills, vibration mills, planetary mills and centrifugal mills, impact self-grinding machines , high-frequency current grinding, ultrasonic pulverizers and the like The application of high-energy pulses and low-temperature plasmas depends on the degree of selective dissociation of minerals from the continuum. However, as the analysis shows, the above methods and equipment do not actually consider the relationship between the high-energy type and the mineral properties (elastoplasticity, thermal properties, magnetic properties, electrical properties, etc.) in the continuum, nor the need The relationship between the power and frequency of inertia and the physical or electrophysical parameter values ​​of minerals in the continuum.
Specialized research can be done using existing equipment to determine these relationships. These studies include:
(1) determining the different optimal ranges of high energy effects used based on the physical or electrophysical properties of the mineral raw materials;
(2) determining the quantitative relationship between the power required for high energy action and the lattice parameters and properties of minerals in the continuum;
(3) Establish the main technical features of new types of equipment that use different types of high energy to selectively dissociate ore particles.
According to the above research results, the frequency, amplitude and vector of the shock wave can be determined to ensure effective softening of the ore during the blasting of the stope. The blasting parameters can be adjusted based on the gas composition of the blasting material and the distribution of blasting holes in consideration of the occurrence of the deposit.
In short, some measures can actually solve the problem of strength softening of ore and selective dissociation of minerals from continuum under the premise of reducing energy consumption, investment and production costs.
(3) Improve the classification efficiency of ore particles according to particle size
The high efficiency separation of minerals from the beneficiation equipment is obtained within the range of particle sizes that are effectively treated, and the particle size range depends on the screening efficiency and the classification efficiency.
The essence of strengthening and increasing the efficiency of the screening is to increase the probability that the particles of the desired size will pass through the openings in the screen of the screening machine. At present, in order to do this, it is possible to use a "active" screen surface - an elastomer with a wave-shaped screen surface; a screen surface with direct excitation; a screen surface with different vibration parameters or vibration intensity gradients (screen surface) Different parts or a sieve surface). Further perfecting the screening process is related to the research results of the quantitative rule of particle interference settlement.
It should be pointed out that the use of fine sieve instead of hydraulic grading can reduce the degree of muddyness of the recovered minerals, improve the accuracy of separation of materials according to particle size, and improve the number quality indicators of grinding and beneficiation operations. The concentrated slurry can be sieved (solid content 60% to 65%) using a hydraulic screen having a sieve surface made of an elastic polymer.
The use of precise spiral feed ports and swirling devices for wear resistant materials (ceramics, special rubber, polyurethane, etc.) as well as variable speed pumps and automation systems can increase the efficiency of the cyclone set in the grinding circuit. Further improvement in the efficiency of the cyclone component level depends on the results of the study of the motion of the particles on the wall of the cyclone.
Second, the mineral processing method of useful minerals
The main beneficiation methods are re-election, magnetic separation, electric selection, radiant beneficiation and flotation.
(1) Gravity beneficiation
Under the interference conditions of gravity, centrifugal force (central force) and medium reaction force, the deepening of the understanding of particle motion law is the basis for the perfection of gravity beneficiation theory.
By solving the particle motion equation under the force, the optimal hydrodynamic parameters of the existing re-election process can be evaluated, and the rationality of the new re-election equipment structure can also be evaluated. Using the theory of stochastic processes, the distribution of particles in the separated product can be determined. The kinetics of the process can also be described, linking the beneficiation results to the production capacity of the re-election equipment.
Based on the results of modern theoretical research, the development of the gravity beneficiation process is perfect, including the destruction or creation of certain structured suspended solids with a certain viscosity and density in the separation zone of re-election equipment. In practice, the following methods can be used:
1. Change the structural parameters and kinetic parameters of gravity ore dressing equipment (centrifugal sorting machine, spiral concentrator, etc.);
2. Apply special chemicals and materials to adjust the properties of the sorting medium, or adjust the strength of the liquid stream and the characteristics of the circulation in the sorting area;
3. Apply vibration or ultrasonic to improve the effect of jig, shaker and heavy medium sorting; develop new re-election equipment such as vibrating separator, vibrating chute and vibrating shaker.
According to the results of the gravity beneficiation process, particularly the fluid flow near the wall of the sorting device, a process for efficient sorting of fines and slime can be established. The use of reciprocating oscillations in the chute and shaker, as well as changing the helical pitch of the spiral separator and changing the spacing of the grooves of the centrifugal separator can all improve the sorting effect.
(2) Magnetic separation
In the magnetic separation, the selectivity and efficiency of material magnetic separation increase with the increase of the difference of the magnetization coefficient of the material, the enhancement of the magnetic uniformity of the separation magnetic field and the reduction of the particle size range of the separation raw materials. Therefore, the development of new magnetic separation methods (and magnetic separation equipment ) and improved sorting efficiency are actually achieved by increasing the separation force (magnetic force and centrifugal force), increasing the magnetic field magnetic induction strength and neutralizing the surface forces that cause flocculation.
In order to increase the difference in the specific magnetization coefficient of the sorted mineral, the raw material may be subjected to pre-magnetization treatment (magnetization) or electrochemical (cathode) treatment of the slurry, not to mention, in the past, the raw material is subjected to magnetization roasting treatment.
The development of a new high-latitude magnetic separator (magnetic filter) and the application of low-temperature superconductors and high-temperature superconductors can increase the magnetic field force. This can increase the magnetic field induction intensity by several orders of magnitude, expand the type of material selected, and improve the magnetic separation efficiency.
In the selection of ferromagnetic ores and materials, in addition to the specific magnetic susceptibility of the particles, magnetic coercivity, residual magnetic induction and demagnetization factors also play an important role. The formation of magnetic agglomerates in the magnetic field of the magnetic separator or magnetizing apparatus, and the degree of preservation of the magnetic agglomerates after leaving the magnetic field are all related to the magnitude of the above values. Thus, after each section of the magnetic material can be demagnetized new electromagnetic sorting machine, the iron ore for dry sorting separator having a rotating magnetic field in the magnetic ore separator may reduce the strength of the magnetic field 6/7 ~ The 7/8 electromagnetic cyclone has great significance.
It should be pointed out that the future development of magnetic separation will depend to a large extent on the application of the hydrodynamic motion law of particles in the magnetic field under the action of gravity.
(3) Electrical selection
At present, the electrical conductivity of the main application materials (electrostatic sorting machine, corona electric sorter, corona electrostatic sorting machine), point mode (friction electric sorter, wind electric sorter) or dielectric coefficient and temperature The difference in electrical properties during the change (dielectric separator and thermoelectric sorter). Sorting methods based on piezoelectric and photoelectric effects, unidirectional conductivity and other electrical properties will have practical application prospects.
The efficiency of electrification can be improved by heating, frictional adhesion, mechanical action and radiation, application of inorganic and organic agents to change the surface electrical properties of the material, and development of a new type of electric separator.
The following methods can be used to expand the electrical differences of the sorted minerals and improve the efficiency of electrification:
1. Select a suitable charged surface to selectively electrify the sorted minerals when the contacts are energized;
2. heat-treating the mineral to be electrified at an optimum heating temperature in the range of 50 to 300 ° C;
3. Applying the chemical treatment to sort the materials to adhere to the mineral surface, greatly changing the concentration of the charged free carrier and the electron overflow work; when the contact is charged, the agent selectively adsorbs or chemically adsorbs on one of the minerals. Not only can the amount of charge on the surface of the mineral be changed, but also the sign of the charge can be changed;
4. The material is sorted by radiation to activate the impurity level and increase the concentration of the charged carrier in the mineral conduction band. For example, silicate minerals increase the contact charge by several times in the case of infrared radiation (wavelength of 10 - 6 to 1.3 × 10 - 2 m, intensity of 0.7 to 0.9 V/cm 3 ).
The effectiveness of each of the above methods depends on the reliability of the laws governing the changes in the electrophysical properties (Fermi level, electron-to-hole ratio, and total surface electrical state) of the mineral after the above treatment.
(4) Radiation measurement sorting
Among the many possible radiation measurement separation methods and absorption radiation measurement separation methods, the most widely used in industrial applications are self-radiation measurement sorting method, optical neutron method, X-ray radiation measurement sorting method, and fluorescence measurement. Sorting method, optical method, gamma absorption measurement sorting method and neutron absorption measuring sorting method.
While improving the structure of the existing radiation sorter and increasing the sorting machine type, the electronic structure and nuclear physical properties of the separated minerals can be considered and utilized, so as to greatly expand the possibility of comprehensively processing materials, protect the surrounding environment, and reduce the final The cost of production and selection of products.
(5) Flotation
Currently, more than 90% of the non-ferrous metal ores as well as most of the rare metal ores, precious metal ores, chemicals and other raw materials mining mineral raw materials are processed using the flotation method. With various forms of froth flotation, adsorption flotation and agglomeration flotation in many industrial sectors and the widespread application of ecological problems, flotation has developed rapidly.
The use of flotation to solve process, economic and ecological problems, and the further development of flotation are all closely related to the qualitative change of understanding of flotation to quantitative law. The new flotation hypothesis is the scientific basis for this transformation. It is based on the theory of the action of the unit below the flotation: the hydrophobicity of the surface of the suspended particles; the strength of repeated contact of the bubbles with the particles.
According to this hypothesis, the effective flotation of minerals without natural hydrophobicity can only be achieved when there are not only chemisorbed collectors on the surface, but also the presence of physically adsorbed collectors. The thermodynamic conditions of fixation and flotation on the bubbles also satisfy the kinetic conditions. Minerals may be inhibited when the mineral surface lacks any of the two types of collectors. For naturally hydrophobic minerals, only one physically adsorbed collector on its surface is sufficient for flotation.
The new flotation hypothesis can theoretically be used as a basis for determining the regularity of the process, and it can be used to establish a quantitative physical and chemical model for the optimization conditions of the flotation process. At this time, the theoretical calculation method of the boundary conditions of the chemical interaction between the flotation agent and the mineral surface, the pH value which can ensure the optimal conditions for the physical adsorption of the collector, and the determination of the zero point of the mineral are the means for establishing a new erection.
The development of an analytical device that can determine the concentration of a chemical in the slurry phase is the basis for optimizing the theoretically valid physicochemical conditions of the flotation process of the concentrator. This type of analytical device is also needed when checking for environmental pollution and solving ecological problems associated with it.
Flotation shift from quantitative to qualitative understanding of the possibilities and prospects of the law has now been a number of concentrator industrial and semi-industrial tests confirmed the results of research: lead oxide (ЗырÑновÑk Concentrator) and copper oxide ore (ÐлмалыkÑk ЗырÑновÑk concentrator and concentrator) sulfide flotation; copper-activated zinc sulfide minerals and deactivation (ЗырÑновÑk concentrator); cationic collector flotation of sulphide minerals: fluorite (Mongolian concentrator); apatite (apatite company Carbonate mineral flotation (Κаpа-Тау concentrator); flotation of lead-zinc-copper sulfide minerals with slag-based collectors (ЗырÑновÑk concentrator, БелоуÑовÑk concentrator, ÐлмалыkÑk concentrator and Суллваи concentrator) and copper- nickel Different flotation schemes for ore (ЖдановÑk beneficiation); separation of zinc-pyrite concentrate by lime (ЗырÑновÑk concentrator, БелоуÑовÑk concentrator), zinc cyanide separation of lead-copper concentrate (Michalpur Institute of Mines) test).
The change from qualitative understanding to quantitative law of flotation can promote reliable automatic control of the concentrating plant and regulation of industrial processes, improve process indicators and economic indicators, reduce the consumption of chemicals, and solve the surrounding environmental protection problems.
Flotation process model should be based on the kinetics of flotation process, the dynamics of this law is to get the optimal concentration of the agent in the pulp Relations, and this relationship is supported by the automated control system, because floating The physical and mechanical characteristics of the selected device are actually constant. The flotation dynamics equation is the theoretical basis for obtaining the process dynamics law.
(6) Prospects for creating new beneficiation methods and new equipment
The creation of new beneficiation methods and new equipment should be based on the application of combined force fields and radiation: magnetic field action, electric field action, centrifugal force field action, vibration action, ultrasonic action, radiation action, and thermal and chemical effects to change separation. The medium and the surface properties of the particles to be separated.
On the basis of the joint force field, such as the vibration field and the gravity field, a series of new beneficiation equipment can be manufactured: vibrating separator, vibrating chute, vibrating shaker. When a magnetic field, an electric field, and a gravitational field are used in combination, a magnetohydrodynamic separator and a magnetohydrostatic separator are manufactured.
In order to create new effective beneficiation methods and equipment, the piezoelectric properties, dielectric properties and other properties of the minerals were investigated. New mineral separation methods can be part of useful mineral processing and ecologically clean processes.
Third, the separation process of solid phase and liquid phase
(1) Concentration
The concentration process can be enhanced by the use of polymeric flocculants and by magnetic and electrical treatment of the slurry. For example, adding auxiliary powder causes agglomeration of fine particles to cause flocculation of the ore particles, or addition of magnetic particles and application of an alternating magnetic field, or aeration to cause aerated flocculation. The above method can promote the formation of the Qiaolian structure, the adhesion center or the magnetic floc. Optimum concentration conditions can be determined based on the nature of the mineral, the presence of the mineral surface active center, or the pH corresponding to the surface zero point. When the effect of the concentration process is not effective enough, other concentration machines or filter centrifugal dewatering machines of the corresponding structure can be reasonably utilized to strengthen the concentration process.
(two) filtering
The main application is a disc vacuum filter and a filter press with different structures to filter the concentrated product. Through the action of water vapor and the use of chemicals (reducing the viscosity of the liquid phase, the hydrophobicity of the surface of solid particles, etc.), the physical action on the slurry and sediment (electroosmosis, etc.), using new materials made of light and corrosion resistant The fan surface of a disc vacuum filter made of synthetic material and a filter press (Russia) using a Ralox (Finland) filter press or a КМП-22 type high vacuum pump can enhance the filtration process and reduce the moisture of the sediment.
Fourth, the conclusion
The analysis of the existing beneficiation methods shows that there are serious theoretical problems, both in the further improvement and strengthening of the existing beneficiation process, and in the creation of new methods for processing various mineral raw materials. The application of the new beneficiation process can reduce the unit energy consumption and cost of obtaining commercial products, improve the comprehensive utilization rate of raw materials, and solve the environmental protection problems around the current production and production departments. In the mining of mineral deposits - raw material sorting - concentrate metallurgy (chemical) system, priority is to develop the mineral processing theory, technology and process of useful minerals as a prerequisite for improving the comprehensive utilization of mineral raw materials.
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