Cement Quality On-line Detection Based On Laser-induced Breakdown Spectroscopy

For a long time,cement is widely used in the civil,industrial,agriculture,water conservancy,transportation,and defense engineering.It is of great significance for using qualified cement to guarantee the construction and property safety.So,quality test is an important part in the cement production.Throughout the cement production process,the ratio of raw materials is the key to determine the cost and merit of cement.If grasp the kiln feed quality especially the content of major elements,we can adjust the ratio of each raw material belt weigher to make sure the raw materials be optimized.Through this the passing rate into skin and assurance can be improved.In the test process,the traditional analysis methods are cumbersome and time-consuming operation,even radiation hazards.So it is difficult to guarantee the timeliness and safety.Therefore,it is necessary to develop a new kind of technology for the cement quality test under the circumstance of the accuracy.Laser induced breakdown spectroscopy(LIBS)is a new kind laser ablation spectrum analysis technology.Firstly,high power pulse laser was adopted to 'hit' the target and then the spectrum of the plasma was collected by the optical system.Finally,we can achieve qualitative and quantitative analysis of the chemical elements according to the spectrum.LIBS has been recognized as a prospective tool due to its many advantages.In this paper,we describe the development status of cement industry and the traditional analysis method firstly.Then we introduce the development states and the basic principle of LIBS technology.Finally,we construct a cement quality testing equipment based on LIBS technology and verify the feasibility of this equipment.The key parts as follows:1.Develop a method to take powder sample continuous and uniform.It can achieve pneumatic regulator,water filter and cleaning the pipeline,et al.Therefore many problems in taking delivery samples on-line were solved,such as ash fouling,compaction,discontinuous,uneven and the optical system is susceptible to dust pollution,et al.Also,the traditional manual sampling and sample preparation were eliminated at the same time.It is necessary condition for cement quality on-line detection.2.Propose a practical and effective LIBS spectra date processing method based on support vector machines(SVM).First,we conduct the LTE state criterion,normalization and selection.And then,the calibration model for the CaO,SiO2,Al2O3,Fe2O3 and MgO of cement raw meal using SVM function form matlab toolkit was established.The averaging absolute error are 0.22%,0.38%,0.18%,0.022%and 0.036%,respectively.3.A cement raw material quality analyzer which includes pneumatic sample delivery device,laser detection device,signal acquisition and control module,remote module and clean devices was constructed through the optical,mechanical,electrical and pneumatic systems integration.It can achieve accurate measurements of the cement raw materials.Industrial field test results show that the oxide measurement accuracy:Al2O3(0.18%),CaO(0.22%),Fe2O3(0.022%),MgO(0.036%)and SiO2(0.38%),respectively;Three rate measurement accuracy:KH(0.07),SM(0.07)and IM(0.07),respectively;Measuring time:1/3/5/10 minutes optional and maintenance period is 60 days.