The New Ceramic Abrasive Firing Pad Sand

For many years, some conditional large vitrified abrasives factories have taken physical examinations many times for workers, and the ratio of kiln workers having suffered from silicosis is increasing year by year. Silicosis is an occupational disease of endangering health seriously, which is caused from the dissociating silicon dioxide dust inbreathed for long time, resulting in fibrosis between lungs and silicosis tubercle.The serious one has the lung function influenced, lose labour capacity, even is afflicated with the pulmonary heart disease, the heart failure and breathe exhanstion.For these reasons, the new materials of replacement quartz sands as vitrified abrasives setting sands to improve working environment are badly in need for being discovered. This paper analysed and researched the quartz setting sands which cause silicosis of the vitrified abrasives factories. Through consulting a large number of relevant materials, I detected physical and chemical properties of some materials and conducted experiments in input-sintering for vitrified abrasives. Through hard working, a new kind of candidate material to replace the quartz sand was found at last. Main research work and experimental results were summarized as follows:1. The theoretical knowledge about quartz crystal structure was depicted. From it, it can be known that the quartz has the complicated polycrystallinity. During the course of vitrified abrasives sintering and cooling, due to polymorphic transition of quartz, the volume change of the quartz setting sand was inevitable and thus caused the stress and crackle then reduced intensity and particles site. When the kiln-handling the quartz setting sand dusts fly upward, therefore threaten workers' health seriously. Thus the quartz sand is unsuitable for setting sand of vitrified sbrasives.2. The physical and chemical performances of the quartz setting sand was compared with those of the new-type of setting sand. The physical and chemical performances included: chemical compositions, mineral compositions, denties, absorbing water rate, single particle compression strength, heat expansion coefficient, durable degree, magnetic contents, low melting contents and particle shapes etc. In the comparable tests research,the concept of each kind of performance and measurement meaning,basic principles, experimental set-up, experimental steps, results, analysis and dicussion were introduced. The changes of the setting sand were measured by DTA (differential thermal analysis) in the course of heating and cooling.By the synthesis analysis of chemical compositions and mineral compositions, the new-type setting sand was found a more-component system in fact. According to the content of chemical compositions, the new-type setting sand seen as CaO-Al2O3-SiO2 was estimated.Through comparable experimental studies the following results were found: Water absorption rate of new-type setting sand was four times more than that of the quartz sand. Single particle compression strength was 1-2 times higher than the quartz setting sand, with the increasement of the new-type setting sand application number, single particle compression strength tended to increase. The heat expansion was relatively low and its curve rised slower smoother than that of the quartz sand. Durable degree was three times higher than that of the quartz sand. There seldom existed low melting point matter and magnetic matter. The shape of the new-type setting sand was similar to that of the quartz sand after technique adjustment and took on spherical. What's more, with the increasement of application number, themorphology became better and better. DTA proved there was no heat effect during the whole course of sintering. In other word, there was not any physical and chemical change, which indicated that its nature was stable. By XRD and phase-diagram synthesis analysis, the main compositions of the new-type setting sand were corundum and mullite.The results showed that the mew type setting sand superior to the quartz sand in various performances was more suitable for the setting sand of vitrified abrasives.3. The new-type setting sand was used for tests of vitrified abrasives input-sitering. Through many times experiments, whether the new-type setting sand was used for various types of abrasives or sintered in different classes of kilns, the result was unanimous, that was, there were no binding among the emery wheels, no stain on the surface of emery wheels, and serviceability was completely equal to that of the quartz sand.Technique tests results proved that the new-type setting sand could replace the quartz sand completely as long as the new-type sand was used under specific condition and the input-sitering of vitrified abrasives was operated according with operation keys.4. The economic benefits and social benefits of the new-type setting sand were analysed. From the the point economy estimate, about 7/9 capitals could be saved every year to use the new-type sand other than the quartz sand. Consideration from environmental protection single grain compression strength of the new-type setting sand was 1 -2 times higher than that of the quartz sand, and tended to increase with the increasement of application number, whose durable degree was generally 3 times higher than that of the quartz sand. The dusts of silicon flour will not fly upward when the new-type setting sand being used, thus working environment can be improved, which benefits to the workers' health. On the concerned of this aspect, its benefits can not be estimated.5. Conclusions: The new-type setting sand can entirely replace the quartz sand for the setting sand of vitrified abrasive under the condition of according to production technique and technology qualifications requirement. Application of the new-type setting sand can not only save large capitals but also improve working environment, thus the ratio of suffering from silicon pulmonary tuberculosis can be reduced. It will Become a desired approach to improve the labour condition for the production of vitrified abrasives.6. Work in the future: By so far, such new-type setting sand has not been accepted by the vitrified abrasives producers. One of main reasons is that the leaders' consciousness of improving work environment is not strong. Since the occurrence of silicon pulmonary tuberculosic comparatively slower, 5-10 years in common, even up to 20 years, the disease has not been regarded considerably yet. Another reason is inattentive management in the production process, which caused the setting sand to be brought into finish maching process, and thus resulted in the wasted products of vitrified abrasives. What we need to do in the future is to propagate the new-type setting sand, make great efforts to make conditional vitrified abrasives factories admit and adopt the new-type setting sand.