Grinding is one of the most widely used methods of obtaining solid particles of controled/ desired distribution systems in all branches of industry. Enlargement of this process is often based on experience and on trial and error methods that requires a large number of experiments. The development of mathematical models enabled the transfer of results to a larger scale in similar systems. The proposed researches were conducted in a laboratory scale. The modeling of the grinding process by the population balance included a description of the kinetics of dolomite grinding by kinetic parameters and the development of models that enabled the estimation of kinetic parameters on the basis of the particle size, the geometric characteristics of the mill and the process parameters. Rajamani and Herbst model is suggested for the development of selection function in a ball mill under given conditions process. The selection function was determined based on the change in the proportion of unbroken material over time for eight size intervals in four mills of different volumes, using one-size interval method. Change of unbroken material content with time is linear.The specified dependence suggests first-order breakage kinetics. The selection function was then described by the Rajamani Herbst model. Laboratory-level researches and the development of mathematical models for transferring results to a larger scale is a potential way of reducing energy consumption.
In maintaining cooling systems, one of the biggest challenges is to control the corrosion process. Various corrosion inhibitors are often used for this purpose. Which type of corrosion inhibitor will be chosen depends on the material from which the plant has made. The main causes of corrosion in these systems are: pH, dissolved gas, ammonia, temperature and microbiology. In this paper it was studied the efficiency of two multicomponent commercial corrosion inhibitors based on phosphates and one of which containing zinc chloride. For the purposes of research, the pilot plant of open recirculation cooling system is constructed and made of stainless steel (EN 1.4301) and copper (EN 13601). Experiments were performed in a simulated cooling water witch recirculated for 3.5h. For the purpose of accelerating corrosion processes, it was added a corrosion activator (5% NaCl). It was monitored the corrosion rate of the mentioned materials in the cooling water with the corrosion activator, with and without inhibitor. Corrosion rate is determined by using corrosion coupons according standard ASTM D2688 and by analyzing physical-chemical parameters of cooling water. The results showed it was achieved higher protection efficiency for copper and stainless steel by using an inhibitor containing zinc chloride in addition to phosphate.
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