Cement grinding station

1.Close-circuit grinding process of Cement grinding station

According to yearsexperience, our company promotes pre-grinding process of reducing the size of materials into the mill and multi-broken-little grinding.This process can improve capacity of mill and lower power consumption. If the fist bin of ball mil move outside the mill to crush, Efficiency of crusher can reach 25% to 40%. According of reports, efficiency of ball mill can improve 30% to 50% and power consumption can reduce 10% to 20%,then Because of the grinding clinker grinding narrow particle size distribution, it can improve cement particle distribution , lower average particle size and characteristics and increase uniformity coefficient,so as to enhance the strength of concrete material.
(1)Pre-grinding process
Use of pre-grinding of cement grinding process, in the new dry process production line of more than 2,000 t/d, was widely used and has become a new trend, pre-grinding equipment, mainly roller press and vertical mill (roller mill).From the energy efficiency situation, roller press is slightly higher than the vertical mill, but from the operation of the feed particle size stability and adaptability of view, vertical mill is superior to roller press.From the domestic use of situation, regardless of the use of roller press or vertical mill , as pre-grinding device, be eligible for energy-saving effect of increasing production, the yield increased up to 33% ~ 100%. In contrast, the use of roller press slightly more difficult to maintain , the roll surface wear cycle of approximately 6000 hours, after which must be removed to re-surfacing repair process. The vertical mill operating rate, life cycle of the roll surface to reach more than 20,000 hours, maintenance workload less, but investment of vertical mill is higher than the roller press.

(2)Inner structure improving inside the ball mill

The ball mill inner structure is the important factor which influencing the grinding capacity, the important for the improving of close circuit grinding system is to improve the mill liner and grinding media graduation. Normally in cement mill, the first bin adopt the step liner which has higher lifting capacity, second bin adopt classification liner composted by two kind of liner, this kind of classification liner is easy for grinding media grading, completely bring grinding function into full play.

The perfect graduation of grinding media is one focus of cement grinding technique, there is a lot of influence factors, it should take inlet size and its grindability into consideration, configuration with separator, residue curve of mill and finished product strength requirements and etc.
(3)Using Horomill (horizontal roller mill) and the high efficiency separator machine composed of closed-circuit grinding system.
The grinding system consisting of Horomill and TSV Separator compare energy ball mill to save 33% ~ 39% energy, then cement grinding power consumption up to 25 kW / ton (surface area of 420 m²/ kg). Products particle distribution is similar to ball mill,but the strength of cement is increased slightly. The main equipments of this mill grinding system is less and the process is simple and convenient layout, then construction and civil engineering costs can be significantly reduced. This mill stable than the vertical mill operation, high efficiency, small load cycles than the roller press, the pressure is low, currently at home and abroad has been used for more than 20 units, operating normally.
2.Open-circuit grinding system
(1)Transformation of open-circuit grinding system is mainly by high-yielding and fine grinding technology,
the bin quantity is different.the high finess high capacity mill is set one to two bin more than common tube mill,the bin quantity is decided according to the mill size and its rate of length and diamter(L/D)

(2)The proportion of bin is different. Readjust the proportion of bin, compare the common tube mill, it short the length of steel ball bin, increase the length of steel bar
(3)It set double layer between bins. in high finess high capacity tube mill, it set double layer diaphragm for dividing each bin. It set double layer diaphragm with dividing unit for separating the coarse particle and finess, its function and principle is similar with the separator. the finess which reach setting size value will flow into next bin smoothly, the size which does not reach the size in the setting value will go back to the last bin for continuing grinding until it is qualified.
(4)Adopt diaphragm which is small grate holebig ventilation. The grate hole of diaphragm width is 6mm.the effective area of grate hole is about 15%. Compare to the common mill, the width of grate hole is less, but the effective area is more. The distribution type of grate hole is radial shape. The difference from concentric circle grate hole is less flow speed, but is difficult for material returning.
(5)The grinding media graduationsize is different. According to the different ground material, cement type and etc, each bin will use different type grinding meida.
(6)The high finess high capacity tube mill is modified according to the above mentioned items, the material is treated in order from crushing to grinding, finally to finished product and then discharged out of mill.
(7)Adopt high finess technical to improve the common open-circuit mill, it can increase 20% of the mill capacity ,the finess decrease about 1.5%, the specific surface area increase about 35m²/kg.