Technical measures of cement grinding system optimization

Published on:2015/1/30 11:26:49

Keyword:Crusher, shredder
Introduction:Preface in cement production & other;Two grinding burn & throughout;In the three major link, & other;Grinding & throughout;Is the necessary premise of...

The foreword, ,
in cement production & other;Two grinding burn & throughout;In the three major link, & other;Grinding & throughout;Is the necessary premise of clinker burning, it is the core in determining the quality of cement products;At the same time, & other;Two grinding & throughout;Power consumption accounted for about 70% of the cement production experience total power consumption, of cement grinding power consumption accounts for about 40% total power consumption of cement production.In & other;Two grinding & throughout;Because, cement grinding material is much worse than raw materials, and cement fineness requirement is higher, so the grinding than the power consumption is high, about 1.5 times than the consumption of raw material grinding.With the new standards, full implementation of ISO9000 cement cement fineness requirement will be more strict;At the same time in order to effectively guarantee the early strength of cement, must also change the grain size composition of cement, improve early strength of fine particle concentration.China cement plants mostly use ball mill for cement grinding equipment, it is well known that the ball mill of effective energy utilization rate is only 2% or so, so improve the utilization ratio of energy potential is very great.China's annual output has reached 500 million t cement, in terms of cement grinding power consumption reduced by 10% (an average of about 3 KWH\/t), it can power saving a year 1.5 & times;109 KWH.Electricity price to $0.5 per watt meter, the grinding cost can reduce nearly 800 million yuan each year.Another Angle, in recent years, through to the sintering process improvement and a series of technical reformation, various type kiln clinker production capacity have different level of ascension, especially through a shaft kiln kiln diameter increased and adoption of mineralizer and technical measures, such as seed production capacity of more obvious rise, make originally with the grinding equipment of form a complete set of widespread the problem of insufficient capacity.Take effective measures, efforts to promote the production of cement grinding system ability, at the same time reduce the grinding energy consumption etc by the vast number of engineering and technical personnel with the researchers pay close attention to, a lot of positive beneficial research explore repeatedly reported with technology innovation, and obtained good effect.Involved to promote the efficiency of cement grinding, grinding process, equipment and operation parameters, and many other factors, to effectively improve the production capacity of the whole system, should be comprehensive analysis of various factors, a comprehensive optimization.This paper combined with the technological achievements and progress in recent years some factors will affect the ability of the grinding system more comprehensive analysis of the composite.& have spent
1 cement grinding system high energy-saving technical measures & have spent
1.1 grinding process & have spent
1.1.1 closed circuit grinding process of
in terms of grinding process, and the present are open circuit and closed circuit.& have spent
advantage is that the former process is simple, the material is the finished product after grinding.Faults is the material within the grinding velocity is slow, long residence time, in order to ensure the final particle size all conform to the requirements, has worn thin material also can't timely discharge of mill, often through grinding phenomenon.Production capacity is relatively low open circuit grinding system, high energy consumption, not can flexibly adjust the final fineness.
the latter added powder equipment, can in a timely manner will have fine powder discharge grinding, effectively avoid the phenomenon of grinding, and can be adjusted by adjusting the working parameters of classifier flexible finished cement fineness.In addition, the closed-circuit grinding material flow speed, the storehouse of the grinding medium properly bear the crushing or grinding task, so the production increase, power consumption is reduced, especially for cement fineness requirement is high, the advantages of high yield and low consumption is more significant.The production instance of the point of view, such as a factory & phi;3 m & times;11 m cement mill from open to take SEPAX—3.5 after classifier closed circuit system, the output from 20 t\/h up to 27 t\/h, grinding power consumption is reduced from 52.8 kWh\/t to 42.3 kWh\/t [1], the yield increase 35%, power consumption reduced by 19.9%.
can say, adopt close-circuit grinding is grinding handicraft of cement powder will be development trend.& have spent
1.1.2 pre grinding (grinding) multi-stage tandem mill process & have spent
as is known to all, ball mill as grinding device is compared with the ideal, but as the crushed, or broken equipment, it is inefficient.The granularity larger 10 mm or even dozens of mm of material crushing experiences from inside moved to grinding, in special crushing equipment, is an effective way of improving the capacity of ball mill production.& other;More crushing less grinding & throughout;, that is, efforts to reduce the grinding particle size is over the years, cement grinding operation practice shows people with precious experience, thus came into being in the process of the crushing (grinding) process is very natural.According to the theory of crushing brittle materials from several millimeters to several millimeters fragmentation, its disintegration is the essence of internal crack continue producing with extension, and contribute to the experience of the outside world is that a certain way to exert strong force & ndash;& ndash;Crushing force.Usually adopt compression crushing with impact crushing method, the corresponding system has rolled + ball mill with impact crusher, ball mill grinding two pieces (grinding) process.& have spent
(1) rolling mill + ball mill grinding process.This process also includes a variety of cascade vertical mill and ball mill grinding process configuration, here only to rolling mill + cascade of ball mill grinding system is analyzed.Shattered cement clinker of advanced rolling mill, powerful roller pressure from the dozens of mm crushed to a few millimeters or even more fine after into the ball mill.Because of the clinker particles by the roller grinding at the same time, also produced many micro cracks, therefore in the ball mill is more easily shattered and further soon to enter the stage of grinding.In this kind of grinding system, the main task of the ball mill is grinding, therefore, can choose a smaller size of the grinding medium coarse grinding storehouse, grinding surface area increases obviously is beneficial to promote the efficiency of grinding, thus greatly enhance the production capacity of grinding system.Reportedly [2] , adopt ball mill roller mill + cascade after grinding process, cement grinding system of 40% can promote production, grinding power consumption can be reduced by 10%.
(2) the impact crusher + ball mill grinding process.The development of the fine crushing equipment is one of the hot spot of the clinker grinding Angle beforehand.Since the 1980 s, the fine jaw crusher clinker crusher to the impact of various type fine crusher in recent years, effectively promote the cement grinding process of the reform and innovation.The clinker fine crushing equipment to roughly the following several kinds: fine jaw crusher (PEX), vertical counterattack crusher type (PCF), vertical hammer crusher (PCLS), vertical shaft hammer type fine crusher (XCL type), high efficiency and energy saving crusher (PGXJ type), vertical impact crusher with vortex impact crusher, etc.Their average discharging granularity can be up to 3 mm to 5 mm, vertical impact crusher in the discharge of particle size of < 2.5 mm can be up to 80% ~ 90%.& have spent
should be the pointed out that both rolling mill and the above all kinds of fine crusher, or smash technology are the prominent problems on the roll surface of working parts material, but the work parts with high hardness and high wear resistance, to ensure that they work effectively for a long time;Otherwise, the use of short life and change cycle is bound to affect system operation rate and production capacity, as well as greater material consumption, conducive to economic benefit of ascension.& have spent

1.2 ball mill structure improvement ball mill itself structure is also important to affect the grinding ability of the Angle.It includes the setting of each pod length in the grinding, liner board, storehouse, in the form of type, hole rate and arrangement, etc.
(1) the length of the mill in the storehouse.Today, more than the length of the coarse grinding ball mill all kinds of warehouse is according to the biggest size is 25 mm, length is generally relatively long and coarse grinding storehouse.With the introduction of pre grinding process, the grinding particle size obviously decreases, and the coarse grinding pressure on the grinding greatly slow down, so, if I continued the original pod length, can cause coarse grinding warehouse capacity surplus, fine grinding, warehouse capacity tight imbalance.In order to make the warehouse capacity matching, many manufacturers took appropriate shorten length, increase the fine grinding, coarse grinding storehouse pod length, good results are obtained.Such as & phi;2.2 m×6.5 m a storehouse of mill design length of 2.75 m, some manufacturers will be reduced to 2.45 m, 210 m, even coupled with corresponding adjustment of grinding medium, like production results have been achieved.& have spent
(2) the storehouse board insulation improvement.In recent years, the development of the high fine grinding promoted the improvement of every storehouse board, make it has cut off chunks of material, to prevent the grinding body string of warehouse, ensure that the traditional functions such as ventilation, forced feeding, also has the function of the new classification.Such as isolation system with sizing screen storehouse board, besides have forced feeding effect, also can be the coarse particles of larger size to return back to the continuous grinding coarse grinding storehouse.In & phi;2.4 m×13 m mill installed inside the warehouse after plate isolation, mill production increased by 28.1%, grinding power consumption was reduced by 15.3%, the grinding medium consumption was reduced by 26.8% [4], .Because the scale effect, into the material particle size and stability of the fine grinding storehouse greatly ascend, is in a way to avoid the existence of coarse particle, at the same time to the circulation rate and stability of stabilizing system of the whole system working status has positive significance., according to the report, [2] will alternate bay board from perpendicular to the axis of the grinding machine to tilt 45 & deg;~ 60 & deg;Installation, eliminates about 4% in the grinding & other;Die material layer & throughout;, strengthen the ability of the impact of the grinding medium with friction, and increase the ventilation area, modified & phi;1.83 m×7 m the output of cement mill from 5.5 t\/h up to 7.5 t\/h, increase rate of above 36%.& have spent
?(3) the use of new type of plate.Mill lining board varied in form, function and effect is not the same, of ladder lining board is cement grinding coarse grinding storehouse the most widely used form of lining, the Archimedes spiral shape curved surface to ensure the experience that can be balanced to grinding medium mill operation up to a certain height, so as to increase its impact crushing material, but this kind of lining board still cannot overcome the defect of steel ball with the point contact.The rounded square plate?Angle spiral plate, grooved liner the emergence of new type lining, such as the lining board with grinding body tend to be more reasonable.Cement plant, huixian henan yanshi county cement plant, anhui chaohu cement plant and other first use the annular groove activation lining board, mill production are increased by about 15%, grinding power consumption reduced by 15% ~ 19%, [5] .This is due to the ball with plate 120 & deg;Arc contact, increase the grinding area, between the ball and lining board with a layer of difficult from materials, adequate use of the sliding friction between each other, increase grinding efficiency.Angle spiral plate is by changing the grinding motion law of the grinding medium, has given grinding body from the Angle of variability, to improve grinding medium and material of the cross through contact with mixed enough grinding, and the steel ball automatic classification to improve the grinding efficiency.On the basis of the annular groove activation lining board, and the research and development the new energy-saving lining & ndash;& ndash;Ring groove surface pair of lining board [2, 6], , the lining board to make the improvement of grinding medium is more reasonable, grinding medium and material of the contact friction opportunity more and more, production can be further increased by 10% ~ 18%, power consumption reduced by 10% ~ 20%.& have spent
1.3 grinding medium load and its grading & have spent
?(1) grinding medium with discretion.In the ball mill grinding medium load is usually yes, according to the filling coefficient or fill rates generally more than the filling coefficient of ball mill is 0.28 ~ 0.32.A lot of research and practice has proved that the filling coefficient of grinding medium can increase properly, can be appropriately increased grinding medium load, especially fine grinding storehouse.First of all, increasing the grinding medium filling without changing under the premise of grading can increase the chances of crushing or grinding;Secondly, after filling rate increased, the grinding body's center of gravity to be near the axis of the grinding machine, and no significant increase in total impact torque, so it will not affect the power transmission.In fact, mill motor power reserve completely allowed to increase load in a certain range.Practice shows that [2] , & phi;2.2 m×6.5 m with & phi;1.83 m×7 m grinder, grinding medium respectively by 31 with 21 t t t increase to 34 with 24 t, mill production can improve 20%.& have spent
?(2) grinding medium graded optimization.Mill grinding body in graded optimization has been the hot topic is discussed in the cement grinding technology.In recent years, many reports of the practice of the steel ball gradation, also has a lot of experience of regularity, such as average ball diameter, steiner curve method such as [7] .Grading is bound to solve several important parameters: the ball diameter, the average ball diameter and steel ball (or section) series and various proportion.In fact, the influencing factors of grinding medium grading, been reported many method is only in a particular material and process under the condition of the better choice.The following should be considered in the grinding medium grading must some opinions on the issue.& have spent
(1) the ball diameter and average ball diameter calculation should consider the material easy to grind or fragility.Different type kiln calcine material its fragility is difference, even the same type kiln calcining clinker, since there are different process formula and firing conditions, its characteristic is also often differ.Other, mixed material of slag, because its size is relatively small, and difficult to grind, therefore, with the ball should be appropriate to increase the small size of the ratio of grinding medium.& have spent
(2) the primary crushing in grinding process for the coarse grinding storehouse grinding medium average ball diameter and its series of adjustment should be depending on crushing equipment status in advance.Specifically, by rolling and extrusion of clinker in addition to the grain size is small, its internal there are a lot of crack defects, and thus more easily into the grinding after the crushing;And after impact crushing the clinker particles is more uniform, broken Lord if caused by internal crack propagation at the same time, the particles is relatively small, the defect reason into the relatively difficult pieces after grinding.So, match ball, of the two kinds of pulverizing system should be treated differently.
(3) the cement grinding fineness and performance.Finished cement fineness is one of the quality of its direct.For open circuit system, the index obviously depends on the grading of grinding mill in body;On the CCTV system, if the grinding fineness of cement is too thick, will inevitably lead to circulation rate is too large, increased the pressure of the classifier.Another Angle, the classifier of critical separation particle diameter is 0.08 mm?That is, 80 & mu;M is defined, it may not be changed to less than the size of the grain size and content, and for some cement, or ask for enhance early strength, 28 days or want to improve strength, so the grain size distribution of cement have corresponding requirements, if the former, hope fine?The < 10 & mu;M's content is bigger, to do this, must increase the grinding in the proportion of small size grinding medium.& have spent
1.4 lining with the material of grinding medium of
the stability of the grinding process conditions in a very large extent, depends on the lining board with the material of grinding medium, if liner material hardness, wear resistance and shock resistance is poor, the surface is quickly changed the original geometry shape;By the same token, the grading of grinding medium in grinding machine operation experience is a dynamic, continue to change, if the abrasion resistance and mechanical strength of grinding medium can not meet the requirements, after a period of grinding operation, the original optimal gradation obviously difficult to guarantee.Though people a lot of make up for the ball, but after all is not the same size of the grinding medium wear rules in grinding experience is not the same, so make up for the ball can continue to load at best relatively balanced, not continuous gradation is consistent.So, improve the lining board with the material of grinding medium is grinding medium grading with mill working conditions long-term stability and promote the fundamental guarantee of the operation rate and production efficiency.& have spent
for lining board, long-term work necessary material conditions is: has overall uniform hardness with the organizational structure, with high impact fatigue strength, low wear rate, deformation, continue to crack, apparently ordinary steel plate is difficult to have those characteristics.High chromium white iron plate high hardness, wear resistance, but the concentration of stress sensitivity is strong;Bainite ductile iron plate with higher resistance to bending fatigue strength and good wear resistance, compared with high manganese steel lining plate, life can promote more than 1 times;The use of multiple low alloy steel plate life expectancy of high manganese steel lining plate more than four times.& have spent
grinding media consumption is the main material consumption in the cement grinding experience, it includes the friction between grinding medium and with material between caused by the loss caused by abrasion with their fracture.Grinding medium loss is too big, not only affect the grinding capacity of mill, and frequent downtime repair ball lead to operation rate is low and the working condition is not stable, also directly caused by grinding cost of ascension.Ordinary steel ball grinding 1 t cement grinding medium loss roughly 1000 g, filling the ball cycle is about half month more, the ball bearing steel, high chrome wear-resisting, low alloy steel ball of the loss can be reduced to 30 ~ 40 g\/g\/t t, the average abrasion is about 60 g\/t, the loss is only 1\/15 ~ 1\/20 of the former, filling the ball cycle can reach more than half a year.Such as jidong (290.67 yuan\/ton, 0%) of cement plant cement grinding ball period for 1 year.In & phi;2.2 m×6.5 m ball mill as an example, its design and production for 14 t\/h, ordinary steel ball wastage for 14 kg\/h, wear-resisting ball of 840 g\/h.If the price with 6000 yuan respectively, 3000 yuan\/t\/t, are respectively 42 yuan to 5 yuan\/h\/h.7000 h meter per year, that alone, the latter than the former to save 260000 yuan;If considering factors such as operation rate and to promote the efficiency of grinding and its economic benefits is self-evident.Not ugly, wear-resistant ball price, although more expensive, but its superior performance can greatly reduce the work intensity of clearance for the ball, and greatly stable grinding machine working state, promote mill grinding ability, but also significantly reduce the grinding cost, can bring considerable economic benefits.& have spent
worthy of comment is that the material of fine grinding, grinding greatly weakened the influence of volume density, it is important to its hardness and surface area, respectively in the experimental mill & phi;10 mm heel & phi;With the size of 5 mm steel ball with porcelain ball slag fine powder grinding test results showed that [9] , at the same grinding conditions, after the grinding material particle size distribution (especially 10 & mu; m ~ 30 & mu; m level with < 10 & mu; m level), to reduce the transmission power, reduce gringing enercy have positive significance.& have spent
1.5 grinding agent & have spent
More than cement grinding aid as the surfactant, the active groups of adsorbed on the surface of cement particles orientation can reduce the surface of cement particles than with strong dispersion effect is the essence of grinding efficiency.According to crush balance theory, to a certain operation parameters under the premise of when grinding experience to a certain extent, that there will be a particle crushing and reunion of micro-sized particles speed equal & other;Balance & throughout;, under the condition of grinding material of fine particles in their reunion and the grinding medium with adhesive on the lining board is inevitable.This will no doubt greatly weaken the effect of grinding medium, causes the grinding efficiency is decreased obviously.After joining grinding agent, can basically eliminate the above phenomenon, which will be micro-sized particles coated abrasive grinding ability of the body & other;Liberation & throughout;Come out.At the same time, the fine particles of depolymerization and desorption changed state of grinding, which destroyed the original pieces balance, can in the new grinding condition reach the balance of cement particles finer new crushing.Practice has proved that adding grinding agent can effectively improve mill production while dramatically increase the cement specific surface area, which means that the fine particles in the cement content increases, is helpful to improve the early strength of cement.
at present, the research and development of the cement grinding aid is multifunctional composite development, namely in grinding of grinding agent not only can effectively improve the cement mill grinding efficiency, and to have reduce the water slurry cement or concrete, improve its liquidity, and the role of the mechanical properties of hardened cement paste.& have spent
2 over
in order to adapt to the request of the new standard ISO90000 cement, cement grinding system improvement and operation parameters optimization is very necessary and urgent.Closed-circuit grinding because of its flexibility of energy saving and cement fineness control has become a development trend.Cement clinker into the ground before the crushing significantly enhance for cement mill production, reduce gringing enercy has positive significance.Clinker after pre grinding, the grinding particle size decreased greatly, therefore, of the length, in the mill lining board structure and form and the size of the grinding medium and grading shall make corresponding adjustment and optimization.Adopted with gradation of storehouse board is more conducive to control the overall cement fineness and improve the content of fine particles.Adding multifunctional composite grinding aid to improve cement fineness and its early performance is very effective.& have spentThe foreword, ,

in cement production & other;Two grinding burn & throughout;In the three major link, & other;Grinding & throughout;Is the necessary premise of clinker burning, it is the core in determining the quality of cement products;At the same time, & other;Two grinding & throughout;Power consumption accounted for about 70% of the cement production experience total power consumption, of cement grinding power consumption accounts for about 40% total power consumption of cement production.In & other;Two grinding & throughout;Because, cement grinding material is much worse than raw materials, and cement fineness requirement is higher, so the grinding than the power consumption is high, about 1.5 times than the consumption of raw material grinding.With the new standards, full implementation of ISO9000 cement cement fineness requirement will be more strict;At the same time in order to effectively guarantee the early strength of cement, must also change the grain size composition of cement, improve early strength of fine particle concentration.China cement plants mostly use ball mill for cement grinding equipment, it is well known that the ball mill of effective energy utilization rate is only 2% or so, so improve the utilization ratio of energy potential is very great.China's annual output has reached 500 million t cement, in terms of cement grinding power consumption reduced by 10% (an average of about 3 KWH\/t), it can power saving a year 1.5 & times;109 KWH.Electricity price to $0.5 per watt meter, the grinding cost can reduce nearly 800 million yuan each year.Another Angle, in recent years, through to the sintering process improvement and a series of technical reformation, various type kiln clinker production capacity have different level of ascension, especially through a shaft kiln kiln diameter increased and adoption of mineralizer and technical measures, such as seed production capacity of more obvious rise, make originally with the grinding equipment of form a complete set of widespread the problem of insufficient capacity.Take effective measures, efforts to promote the production of cement grinding system ability, at the same time reduce the grinding energy consumption etc by the vast number of engineering and technical personnel with the researchers pay close attention to, a lot of positive beneficial research explore repeatedly reported with technology innovation, and obtained good effect.Involved to promote the efficiency of cement grinding, grinding process, equipment and operation parameters, and many other factors, to effectively improve the production capacity of the whole system, should be comprehensive analysis of various factors, a comprehensive optimization.This paper combined with the technological achievements and progress in recent years some factors will affect the ability of the grinding system more comprehensive analysis of the composite.& have spent
1 cement grinding system high energy-saving technical measures & have spent
1.1 grinding process & have spent
1.1.1 closed circuit grinding process of
in terms of grinding process, and the present are open circuit and closed circuit.& have spent
advantage is that the former process is simple, the material is the finished product after grinding.Faults is the material within the grinding velocity is slow, long residence time, in order to ensure the final particle size all conform to the requirements, has worn thin material also can't timely discharge of mill, often through grinding phenomenon.Production capacity is relatively low open circuit grinding system, high energy consumption, not can flexibly adjust the final fineness.
the latter added powder equipment, can in a timely manner will have fine powder discharge grinding, effectively avoid the phenomenon of grinding, and can be adjusted by adjusting the working parameters of classifier flexible finished cement fineness.In addition, the closed-circuit grinding material flow speed, the storehouse of the grinding medium properly bear the crushing or grinding task, so the production increase, power consumption is reduced, especially for cement fineness requirement is high, the advantages of high yield and low consumption is more significant.The production instance of the point of view, such as a factory & phi;3 m & times;11 m cement mill from open to take SEPAX—3.5 after classifier closed circuit system, the output from 20 t\/h up to 27 t\/h, grinding power consumption is reduced from 52.8 kWh\/t to 42.3 kWh\/t [1], the yield increase 35%, power consumption reduced by 19.9%.
can say, adopt close-circuit grinding is grinding handicraft of cement powder will be development trend.& have spent
1.1.2 pre grinding (grinding) multi-stage tandem mill process & have spent
as is known to all, ball mill as grinding device is compared with the ideal, but as the crushed, or broken equipment, it is inefficient.The granularity larger 10 mm or even dozens of mm of material crushing experiences from inside moved to grinding, in special crushing equipment, is an effective way of improving the capacity of ball mill production.& other;More crushing less grinding & throughout;, that is, efforts to reduce the grinding particle size is over the years, cement grinding operation practice shows people with precious experience, thus came into being in the process of the crushing (grinding) process is very natural.According to the theory of crushing brittle materials from several millimeters to several millimeters fragmentation, its disintegration is the essence of internal crack continue producing with extension, and contribute to the experience of the outside world is that a certain way to exert strong force & ndash;& ndash;Crushing force.Usually adopt compression crushing with impact crushing method, the corresponding system has rolled + ball mill with impact crusher, ball mill grinding two pieces (grinding) process.& have spent
(1) rolling mill + ball mill grinding process.This process also includes a variety of cascade vertical mill and ball mill grinding process configuration, here only to rolling mill + cascade of ball mill grinding system is analyzed.Shattered cement clinker of advanced rolling mill, powerful roller pressure from the dozens of mm crushed to a few millimeters or even more fine after into the ball mill.Because of the clinker particles by the roller grinding at the same time, also produced many micro cracks, therefore in the ball mill is more easily shattered and further soon to enter the stage of grinding.In this kind of grinding system, the main task of the ball mill is grinding, therefore, can choose a smaller size of the grinding medium coarse grinding storehouse, grinding surface area increases obviously is beneficial to promote the efficiency of grinding, thus greatly enhance the production capacity of grinding system.Reportedly [2] , adopt ball mill roller mill + cascade after grinding process, cement grinding system of 40% can promote production, grinding power consumption can be reduced by 10%.
(2) the impact crusher + ball mill grinding process.The development of the fine crushing equipment is one of the hot spot of the clinker grinding Angle beforehand.Since the 1980 s, the fine jaw crusher clinker crusher to the impact of various type fine crusher in recent years, effectively promote the cement grinding process of the reform and innovation.The clinker fine crushing equipment to roughly the following several kinds: fine jaw crusher (PEX), vertical counterattack crusher type (PCF), vertical hammer crusher (PCLS), vertical shaft hammer type fine crusher (XCL type), high efficiency and energy saving crusher (PGXJ type), vertical impact crusher with vortex impact crusher, etc.Their average discharging granularity can be up to 3 mm to 5 mm, vertical impact crusher in the discharge of particle size of < 2.5 mm can be up to 80% ~ 90%.& have spent
should be the pointed out that both rolling mill and the above all kinds of fine crusher, or smash technology are the prominent problems on the roll surface of working parts material, but the work parts with high hardness and high wear resistance, to ensure that they work effectively for a long time;Otherwise, the use of short life and change cycle is bound to affect system operation rate and production capacity, as well as greater material consumption, conducive to economic benefit of ascension.& have spent

1.2 ball mill structure improvement ball mill itself structure is also important to affect the grinding ability of the Angle.It includes the setting of each pod length in the grinding, liner board, storehouse, in the form of type, hole rate and arrangement, etc.
(1) the length of the mill in the storehouse.Today, more than the length of the coarse grinding ball mill all kinds of warehouse is according to the biggest size is 25 mm, length is generally relatively long and coarse grinding storehouse.With the introduction of pre grinding process, the grinding particle size obviously decreases, and the coarse grinding pressure on the grinding greatly slow down, so, if I continued the original pod length, can cause coarse grinding warehouse capacity surplus, fine grinding, warehouse capacity tight imbalance.In order to make the warehouse capacity matching, many manufacturers took appropriate shorten length, increase the fine grinding, coarse grinding storehouse pod length, good results are obtained.Such as & phi;2.2 m×6.5 m a storehouse of mill design length of 2.75 m, some manufacturers will be reduced to 2.45 m, 210 m, even coupled with corresponding adjustment of grinding medium, like production results have been achieved.& have spent
(2) the storehouse board insulation improvement.In recent years, the development of the high fine grinding promoted the improvement of every storehouse board, make it has cut off chunks of material, to prevent the grinding body string of warehouse, ensure that the traditional functions such as ventilation, forced feeding, also has the function of the new classification.Such as isolation system with sizing screen storehouse board, besides have forced feeding effect, also can be the coarse particles of larger size to return back to the continuous grinding coarse grinding storehouse.In & phi;2.4 m×13 m mill installed inside the warehouse after plate isolation, mill production increased by 28.1%, grinding power consumption was reduced by 15.3%, the grinding medium consumption was reduced by 26.8% [4], .Because the scale effect, into the material particle size and stability of the fine grinding storehouse greatly ascend, is in a way to avoid the existence of coarse particle, at the same time to the circulation rate and stability of stabilizing system of the whole system working status has positive significance., according to the report, [2] will alternate bay board from perpendicular to the axis of the grinding machine to tilt 45 & deg;~ 60 & deg;Installation, eliminates about 4% in the grinding & other;Die material layer & throughout;, strengthen the ability of the impact of the grinding medium with friction, and increase the ventilation area, modified & phi;1.83 m×7 m the output of cement mill from 5.5 t\/h up to 7.5 t\/h, increase rate of above 36%.& have spent
?(3) the use of new type of plate.Mill lining board varied in form, function and effect is not the same, of ladder lining board is cement grinding coarse grinding storehouse the most widely used form of lining, the Archimedes spiral shape curved surface to ensure the experience that can be balanced to grinding medium mill operation up to a certain height, so as to increase its impact crushing material, but this kind of lining board still cannot overcome the defect of steel ball with the point contact.The rounded square plate?Angle spiral plate, grooved liner the emergence of new type lining, such as the lining board with grinding body tend to be more reasonable.Cement plant, huixian henan yanshi county cement plant, anhui chaohu cement plant and other first use the annular groove activation lining board, mill production are increased by about 15%, grinding power consumption reduced by 15% ~ 19%, [5] .This is due to the ball with plate 120 & deg;Arc contact, increase the grinding area, between the ball and lining board with a layer of difficult from materials, adequate use of the sliding friction between each other, increase grinding efficiency.Angle spiral plate is by changing the grinding motion law of the grinding medium, has given grinding body from the Angle of variability, to improve grinding medium and material of the cross through contact with mixed enough grinding, and the steel ball automatic classification to improve the grinding efficiency.On the basis of the annular groove activation lining board, and the research and development the new energy-saving lining & ndash;& ndash;Ring groove surface pair of lining board [2, 6], , the lining board to make the improvement of grinding medium is more reasonable, grinding medium and material of the contact friction opportunity more and more, production can be further increased by 10% ~ 18%, power consumption reduced by 10% ~ 20%.& have spent
1.3 grinding medium load and its grading & have spent
?(1) grinding medium with discretion.In the ball mill grinding medium load is usually yes, according to the filling coefficient or fill rates generally more than the filling coefficient of ball mill is 0.28 ~ 0.32.A lot of research and practice has proved that the filling coefficient of grinding medium can increase properly, can be appropriately increased grinding medium load, especially fine grinding storehouse.First of all, increasing the grinding medium filling without changing under the premise of grading can increase the chances of crushing or grinding;Secondly, after filling rate increased, the grinding body's center of gravity to be near the axis of the grinding machine, and no significant increase in total impact torque, so it will not affect the power transmission.In fact, mill motor power reserve completely allowed to increase load in a certain range.Practice shows that [2] , & phi;2.2 m×6.5 m with & phi;1.83 m×7 m grinder, grinding medium respectively by 31 with 21 t t t increase to 34 with 24 t, mill production can improve 20%.& have spent
?(2) grinding medium graded optimization.Mill grinding body in graded optimization has been the hot topic is discussed in the cement grinding technology.In recent years, many reports of the practice of the steel ball gradation, also has a lot of experience of regularity, such as average ball diameter, steiner curve method such as [7] .Grading is bound to solve several important parameters: the ball diameter, the average ball diameter and steel ball (or section) series and various proportion.In fact, the influencing factors of grinding medium grading, been reported many method is only in a particular material and process under the condition of the better choice.The following should be considered in the grinding medium grading must some opinions on the issue.& have spent
(1) the ball diameter and average ball diameter calculation should consider the material easy to grind or fragility.Different type kiln calcine material its fragility is difference, even the same type kiln calcining clinker, since there are different process formula and firing conditions, its characteristic is also often differ.Other, mixed material of slag, because its size is relatively small, and difficult to grind, therefore, with the ball should be appropriate to increase the small size of the ratio of grinding medium.& have spent
(2) the primary crushing in grinding process for the coarse grinding storehouse grinding medium average ball diameter and its series of adjustment should be depending on crushing equipment status in advance.Specifically, by rolling and extrusion of clinker in addition to the grain size is small, its internal there are a lot of crack defects, and thus more easily into the grinding after the crushing;And after impact crushing the clinker particles is more uniform, broken Lord if caused by internal crack propagation at the same time, the particles is relatively small, the defect reason into the relatively difficult pieces after grinding.So, match ball, of the two kinds of pulverizing system should be treated differently.
(3) the cement grinding fineness and performance.Finished cement fineness is one of the quality of its direct.For open circuit system, the index obviously depends on the grading of grinding mill in body;On the CCTV system, if the grinding fineness of cement is too thick, will inevitably lead to circulation rate is too large, increased the pressure of the classifier.Another Angle, the classifier of critical separation particle diameter is 0.08 mm?That is, 80 & mu;M is defined, it may not be changed to less than the size of the grain size and content, and for some cement, or ask for enhance early strength, 28 days or want to improve strength, so the grain size distribution of cement have corresponding requirements, if the former, hope fine?The < 10 & mu;M's content is bigger, to do this, must increase the grinding in the proportion of small size grinding medium.& have spent
1.4 lining with the material of grinding medium of
the stability of the grinding process conditions in a very large extent, depends on the lining board with the material of grinding medium, if liner material hardness, wear resistance and shock resistance is poor, the surface is quickly changed the original geometry shape;By the same token, the grading of grinding medium in grinding machine operation experience is a dynamic, continue to change, if the abrasion resistance and mechanical strength of grinding medium can not meet the requirements, after a period of grinding operation, the original optimal gradation obviously difficult to guarantee.Though people a lot of make up for the ball, but after all is not the same size of the grinding medium wear rules in grinding experience is not the same, so make up for the ball can continue to load at best relatively balanced, not continuous gradation is consistent.So, improve the lining board with the material of grinding medium is grinding medium grading with mill working conditions long-term stability and promote the fundamental guarantee of the operation rate and production efficiency.& have spent
for lining board, long-term work necessary material conditions is: has overall uniform hardness with the organizational structure, with high impact fatigue strength, low wear rate, deformation, continue to crack, apparently ordinary steel plate is difficult to have those characteristics.High chromium white iron plate high hardness, wear resistance, but the concentration of stress sensitivity is strong;Bainite ductile iron plate with higher resistance to bending fatigue strength and good wear resistance, compared with high manganese steel lining plate, life can promote more than 1 times;The use of multiple low alloy steel plate life expectancy of high manganese steel lining plate more than four times.& have spent
grinding media consumption is the main material consumption in the cement grinding experience, it includes the friction between grinding medium and with material between caused by the loss caused by abrasion with their fracture.Grinding medium loss is too big, not only affect the grinding capacity of mill, and frequent downtime repair ball lead to operation rate is low and the working condition is not stable, also directly caused by grinding cost of ascension.Ordinary steel ball grinding 1 t cement grinding medium loss roughly 1000 g, filling the ball cycle is about half month more, the ball bearing steel, high chrome wear-resisting, low alloy steel ball of the loss can be reduced to 30 ~ 40 g\/g\/t t, the average abrasion is about 60 g\/t, the loss is only 1\/15 ~ 1\/20 of the former, filling the ball cycle can reach more than half a year.Such as jidong (290.67 yuan\/ton, 0%) of cement plant cement grinding ball period for 1 year.In & phi;2.2 m×6.5 m ball mill as an example, its design and production for 14 t\/h, ordinary steel ball wastage for 14 kg\/h, wear-resisting ball of 840 g\/h.If the price with 6000 yuan respectively, 3000 yuan\/t\/t, are respectively 42 yuan to 5 yuan\/h\/h.7000 h meter per year, that alone, the latter than the former to save 260000 yuan;If considering factors such as operation rate and to promote the efficiency of grinding and its economic benefits is self-evident.Not ugly, wear-resistant ball price, although more expensive, but its superior performance can greatly reduce the work intensity of clearance for the ball, and greatly stable grinding machine working state, promote mill grinding ability, but also significantly reduce the grinding cost, can bring considerable economic benefits.& have spent
worthy of comment is that the material of fine grinding, grinding greatly weakened the influence of volume density, it is important to its hardness and surface area, respectively in the experimental mill & phi;10 mm heel & phi;With the size of 5 mm steel ball with porcelain ball slag fine powder grinding test results showed that [9] , at the same grinding conditions, after the grinding material particle size distribution (especially 10 & mu; m ~ 30 & mu; m level with < 10 & mu; m level), to reduce the transmission power, reduce gringing enercy have positive significance.& have spent
1.5 grinding agent & have spent
More than cement grinding aid as the surfactant, the active groups of adsorbed on the surface of cement particles orientation can reduce the surface of cement particles than with strong dispersion effect is the essence of grinding efficiency.According to crush balance theory, to a certain operation parameters under the premise of when grinding experience to a certain extent, that there will be a particle crushing and reunion of micro-sized particles speed equal & other;Balance & throughout;, under the condition of grinding material of fine particles in their reunion and the grinding medium with adhesive on the lining board is inevitable.This will no doubt greatly weaken the effect of grinding medium, causes the grinding efficiency is decreased obviously.After joining grinding agent, can basically eliminate the above phenomenon, which will be micro-sized particles coated abrasive grinding ability of the body & other;Liberation & throughout;Come out.At the same time, the fine particles of depolymerization and desorption changed state of grinding, which destroyed the original pieces balance, can in the new grinding condition reach the balance of cement particles finer new crushing.Practice has proved that adding grinding agent can effectively improve mill production while dramatically increase the cement specific surface area, which means that the fine particles in the cement content increases, is helpful to improve the early strength of cement.
at present, the research and development of the cement grinding aid is multifunctional composite development, namely in grinding of grinding agent not only can effectively improve the cement mill grinding efficiency, and to have reduce the water slurry cement or concrete, improve its liquidity, and the role of the mechanical properties of hardened cement paste.& have spent
2 over
in order to adapt to the request of the new standard ISO90000 cement, cement grinding system improvement and operation parameters optimization is very necessary and urgent.Closed-circuit grinding because of its flexibility of energy saving and cement fineness control has become a development trend.Cement clinker into the ground before the crushing significantly enhance for cement mill production, reduce gringing enercy has positive significance.Clinker after pre grinding, the grinding particle size decreased greatly, therefore, of the length, in the mill lining board structure and form and the size of the grinding medium and grading shall make corresponding adjustment and optimization.Adopted with gradation of storehouse board is more conducive to control the overall cement fineness and improve the content of fine particles.Adding multifunctional composite grinding aid to improve cement fineness and its early performance is very effective.& have spent

Key-word:Crusher, shredder