| The East Hebei region is an important source of iron ore in China.The poor magnetite ore is the largest iron ore type in this area.The traditional crushing process has high energy consumption,accounting for about 60%of the total beneficiation cost.In order to effectively reduce the energy consumption of grinding mill,this paper takes the by-product ore of a built mine in Eastern Hebei Province as the research object.Based on From the Bond crushing theory,the influence of the micro crack on the crushing process of the ore is studied,and the JK software is used to simulate the different grinding process.A new way to reduce the energy consumption of crushing and grinding is explored by consumption simulation.The mineralogical characteristics of the ore are studied in this paper.The results show that the most important metallic minerals in the iron ore are magnetite,a small amount of hematite,limonite,and pyrite,which belong to low phosphorus,low sulfur and poor magnetite quartzite.The primary crystal size of iron minerals in ore is relatively coarse,about 64%of magnetite particle size is larger than 0.1 mm,and the particle size change range is wide,of which less than 0.03 mm is very difficult to choose grain size.The technological mineralogical results of ore samples show that the most important metal minerals in the iron ore are magnetite,a small amount of hematite,a small amount of siderite and pyrite,which belong to low phosphorus and low sulfur poor magnetite quartzite.The primary crystalline granularity of iron minerals in the ore is relatively coarse,and the size of magnetite particles larger than 0.1 mm is about 64%,but the size of grain size is wide,and the refractory particles of-0.03 mm particle size are about 3.5%.The BET theory is used to calculate the specific surface area of different crushing products.The results show that with the decrease of particle size,the cracks on the surface of particles increase,and the corresponding specific surface area also increases.Taking the-0.074 mm particle size as an example,the BET surface area of the HP roller mill increased by 38.27%of the product of the jaw crusher,which means that the product of the high pressure roller mill is finer and the other particle sizes are also in the granular material pellets.The micro crack characteristics of different broken products have been studied by the reverse light microscope and scanning electron microscope.The results show that there are obvious differences in the micro cracks of different broken products,and the intragranular and dissociation cracks produced by high pressure roller mill are more than those of the jaw crusher.Through 5 grain levels longitudinal contrast of-2+0.9 mm,-0.9+0.45 mm,-0.45+0.18 mm,-0.18+0.074 mm and-0.074 mm,it is found that the number of micro cracks in the product gradually increases with the decrease of grain size,and the length and width of the crack increase,and the roughness of the surface of the product increases significantly.The transverse comparison of two kinds of crushing products shows that the number of microcracks in the products of the high pressure roller mill is significantly higher than that of the jaw crusher products.The calculation results of the specific surface area of different broken products by BET formula show that with the decrease of grain size,the cracks on the surface of particles increase and the specific surface area also increases.Taking the-0.074 mm grain level as an example,the product of high pressure roller mill product has a BET specific surface area jaw crusher product increased by 38.27%,which indicates that the high pressure roller mill product in the particle size particles is finer and other grain grade.The test results of the monomer dissociation degree show that when the grinding fineness is about-0.074 mm about 55%and 75%,the monomer dissociation degree of the high pressure roller mill is 1.96 and 1.24 percentage points higher than that of the jaw crusher.When the grinding fineness is about 95%,the monomer dissociation degree of the two materials is basically the same,indicating that it is under the same grinding fineness condition.The material with more micro cracks is easier to dissociate from the monomer,but with the increase of grinding fineness,the trend of change is decreasing.The grain size of the high pressure roller mill products is higher than that of the jaw crusher products,the size composition is finer,the n value is lower,the particle size distribution is even more uniform,so the size distribution results and the number of micro cracks produced in the process of different crushing mode crusher are close to the number of micro cracks.By measuring the main iron mineral content of 55%,75%and 95%of different broken products,the content of magnetite and hematite in fine grade material increases with the increase of the fineness of the grinding.Under the same grinding fineness conditions,the content of iron minerals in fine particles is more,and the distribution of grain size is more reasonable,but the growth trend gradually decreases with the increase of grinding fineness.The standard drop weight and SMC test results of JK software show that the anti impact comminution characteristic parameters are A=79.1,b=0.66,A ×b=52.2,and the parameters of wear and peeling are ta=0.40.Compared with the overall data of JK ore characteristic database,the ore in the middle soft area.The DWi value of this ore is 6.49 kWh/m3.SMCT database has 61%ore in all ores.Its DWi value is less than this value.The ore of this test is medium hard ore.The results of the comminution ratio of Morrell empirical model show that the energy consumption of high pressure roller mill in the conventional crushing high pressure roller mill is 2.49 kWh/t,the ratio of energy consumption of the roller mill is 1.75 kWh/t,the energy consumption of the roller mill is 2.76 kWh/t,the total energy consumption is 8.07 kWh/t,and the conventional crushing ball milling process is used.The crushing energy consumption of the conventional crusher is 1.41 kWh/t,the roughing ratio of the roller mill is 4.25 kWh/t,the specific energy consumption of the roller mill is 4.66 kWh/t,and the total energy consumption is 11.03 kWh/t.The simulation results show that the number of micro cracks in the high pressure roller mill is more,and the energy consumption of the rough grinding ratio and the energy consumption of the fine grinding ratio are lower than that of the conventional broken products.Comparing the results of two crushing products from the grinding and dressing process of wet preconcentration prior to‘two-stage grinding,three-stage magnetic separation,fine screen classification,washing machine concentrating and fine tailings regrinding and regrinding’,the results show that the high-pressure roll products with higher microcrack content have advantages in each index.The concentrate grade obtained by wet preconcentration is 37.60%(HP)and 34.58%(HP)respectively.The magnetic iron loss of the tailings was 0.61%(HP)and 2.52%(JC)respectively.The final concentrate grade of 68.44%(HP)and 67.93%(JC)and the final tailings grade of 6.84%(HP)and 7.67%(JC)respectively were obtained from the whole process test,which met the separation requirements. |
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