Energy Dissipation Mechanism And Crushing Dynamics Research Of Cement Clinker Broken By CKP Mill

With the rapid development of industrialization and urbanization in China,cementis an indispensable construction material for large-scale infrastructure construction.Cement industrial characterized with high energy consumption and emission urges atechnicalrevolution concerning energysavingand emission reduction, otherwiseChina’s economic development and living standards would be negatively affected.Characteristics of cement clinker feed and output from a CKP mill are analyzedto study energy saving and emission reduction issues. Based on the fact that materialspass a CKP mill without recirculation and cement clinker closed-circuit grindingsystems in a common cement plant is a one-node circuit, a real-time and synchronoussampling method of feed, output material and circulating material in the industrialCKP mill are designed. A new sieving program and measure method, the particle sizedistribution curves before and after crushing the cement clinker are obtained. In thisexperiment, experimental and theoretical methods are applied to carry out the numericinvestigation of dynamic behavior and circulating load in the CKP mill. A nonlinearmodel between the circulating load and circulating baffle in closed-circuit systems ofcement clinker is established. By the stability analysis to experimental data of parallelsamples and the dynamic mass balance of the CKP mill, the reliabilityof themathematical models is discussed. Therefore, the crushing rate function of cementclinker and its crushing behavior are studied in the CKP mill, which providetheoretical foundation to practical crushing theory. The main research content isdivided into three parts.(1) According to the laboratory sieving analysis, the particle characteristicequation of cement clinker is established to reflect the featured particle size withaccumulated mass yield at80%and uniformity coefficient. The featured particle sizerepresents the fineness of cement clinker, and the uniformity coefficient can indicatethe material property. Experimental data shows that the uniformity coefficientmatches the property of the two samples and it is not related to experimentalconditions. The fineness of feed, circulating material and output material become finerin turn. The featured particle size of output material is1.40-2.70mm. Under thecondition of same input material, the featured particle size of output material isinversely proportional to uniformity coefficient, and the reduction ratio of cementclinker broken by CKP mill is6-10that belongs to low reduction ratio. This part is thefoundation of this research. (2) Six groups of experimentwith different working conditions aremarked fromAto F. Furthermore, there is a group of experiment marked as ‘experiment09’.Thegrinding efficiency and kinetic equation of CKP mill are obtained by size analysis ofeach size fraction in fresh feed and output material before and after grinding, based onthe particle characteristic equation. The result shows that working condition A has thehighest grinding efficiency andB has the lowest one. In addition, the multivariateregression modelindicates that under the same condition the increase of fresh feedcapacity or recirculating load will improve the mill efficiency, but oppositely theenergy consumption will also increase. In terms of the crushing rate function, theworking condition C with zero recirculatingload has6extremely similarparallelsamples. Therefore, the recirculating loads of each working condition calculated bymass balance model are9%,15%,20%,12%and12%except for working conditionC. Then, the first-order crushing rate function is established and the crushing rate of+0.125mm size fraction decreases with the increase of size fraction.(3)The optimized model is established based on the discrete data of energyconsumption in CKP mills so as to build an energy consumption fractal model ofcement clinker broken by CKP mill. And the fractal dimension of breakageenergyconsumption is3. The output material size of CKP mills matches the feed size of ballmills perfectly, so the lowest total energy consumption can be achieved by joint use ofthese two mills.Finally, according to the Data Envelopment Analysis (DEA), the integral millefficiency of the six working conditions is evaluated. And the whole crushing processin CKP mill is simulated by the Matrix Model. Therefore, the supporting data for theparticle size prediction of product and online monitoring are provided. But the modelhas a high demand for experimental data and need to be further studied in the practicalcase.In conclusion, based on the sampling experiment and sieving analysis in thispaper, the problems such as grinding efficiency, grinding dynamics and energyconsumption in the crushing process of cement clinker in the CKP mill are studied ina comprehensive and detail manner by mathematical modeling and simulation. Thispaperwill lay the foundation for the improvement of cement products quality andenergy saving and emission reduction of mills.