| Paper ash is a crucial factor of paper quality.In the papermaking process,in an effort to improve the stability of paper quality,various fillers are added into the paper.However,too high or too low fillers content will affect the performance of paper,so the quantitative determination of paper ash content is an essential link in the quality inspection of paper production.Traditional determination methods have many problems such as the long measuring time,tedious procedures and large human error.XRD in the ray method can determine paper ash quickly and accurately,but XRD uses the single wavelength X-ray to determine the paper ash,which requires expensive equipment,high operation cost and high requirements for the experimental environment.Therefore,XRD is difficult to be widely used in the papermaking enterprises.In order to solve the deficiencies of XRD in the determination of paper ash,under the funding of "Xi'an Weiyang District Science and Technology Plan Project--Research on Fast,Non-destructive and Accurate Measurement of Paper Ash and Its Components by X-ray(201823)",this study used the X-ray tube as the radiation source and the ionization chamber as the X-ray receiving device,using the continuous X-ray to study the quantitative determination of the total ash and its components of the single filler paper samples.A new method of using the continuous X-ray to quantitatively determine the total ash and its components of paper is proposed.The main results of this paper are as follows:(1)Calculation of the total ash and its components of paperThe X-rays from the X-ray tube were converted into voltage signals by the X-ray receiving device and measuring amplifier circuit.Moreover,the voltage data was collected and the data was fitted to obtain the calculation formula of the voltage logarithmic ratio of paper.Then,on the basis of Beer's law,the calculation formula for the continuous X-ray method to quantitatively determine the total ash and its components of paper was derived according to the compositions of paper and the calculation formula of the voltage logarithm ratio.In addition,by changing the temperature and humidity of the experimental environment,the effect of temperature and humidity on the quantitative determination of the total ash and its components of paper was studied.The results showed that the increase of temperature and humidity would lead to the increase of the air gap voltage and reduce the measurement accuracy of the total ash and its components of paper.According to the change rate of the air gap voltage with temperature and humidity,the compensation value of the air gap voltage was calculated,and the influence of temperature and humidity changes on the quantitative determination of the total ash and its components of paper was eliminated.(2)Determination of the mass absorption coefficient of each composition of paper to the continuous X-rayThe voltage logarithm ratio of paper and the content of moisture,fiber and single filler in the paper were determined experimentally and substituted into the calculation formula of the total ash and its components of paper.The binary linear equations were established to calculate the mass absorption coefficients of the water,fiber and single filler of paper to the continuous X-ray.Then the Grubbs criterion was used to distinguish and remove the abnormal value of the mass absorption coefficient determined by the experiment,and reduce the measurement error of the mass absorption coefficient.The results showed that the mass absorption coefficients of calcium carbonate,kaolin,calcium silicate and titanium dioxide to the continuous X-ray are 0.3915cm2/g,0.1385cm2/g,0.2715cm2/g and 0.4554cm2/g respectively,the mass absorption coefficients of fiber A,fiber B and fiber C to the continuous X-ray are 0.0533cm2/g,0.0584cm2/g and 0.0430cm2/g respectively and the mass absorption coefficient of moisture to the continuous X-ray is 0.0503cm2/g.(3)Establishment and verification of the mathematical model of paper total ashIn order to quickly and accurately calculate the total ash and its components of paper,a polynomial fitting was performed on the total ash and voltage logarithm ratio of the four single filler paper samples,and the best total ash mathematical model was built based on the related data of the fitted curve.Then the paper total ash mathematical model was applied to the actual production paper samples.The results showed that the relative error between the total ash determined by the paper total ash mathematical model and the real total ash is under 5%,which meets the actual production demand.(4)Quantitative determination of paper ash componentsThe continuous X-ray method and the burning method were used to determine the ash components content of the four single filler paper samples and the comparision was made.The results showed that,except for the kaolin paper samples,the ash components content mearsurement error of the continuous X-ray method is less than 5%.In order to solve the problem of large measurement error of the kaolin paper samples,an X-ray diffractometer was used to qualitatively analyze the compositions of the four single filler paper samples.The results showed that the kaolin paper samples contain multiple components,not the single filler paper samples in the true sense,causing the large error in the determination of the ash components content of the kaolin paper samples.The research work showed that the continuous X-ray method can quantitatively determine the total ash and its components of the single filler paper samples,providing a new fast and non-destructive determination scheme for the determination of paper ash. |
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