Search

The paper presents the results of attrition cleaning obtained by testing the samples of quartz sand under laboratory conditions. The tests were carried out in two types of laboratory attrition cell – with circular and octagonal cross section, at different values of operating parameters which are supposed to have the main influence upon the attrition efficiency: suspension density, attrition time and stirrer speed. In each type of attrition cell two series of tests were conducted on two quartz sand samples with different SiO2 i.e. impurity contents. Indicators of attrition efficiency were the content of the particles – 0.063 mm and content of main impurities (Al2O3, Fe2O3) removed through the attrition process. By comparing the results of both series of tests conducted in mentioned types of attrition cells, information on dependence of attrition efficiency on feed material composition, operating parameters and attrition cell construction were obtained.

The quality of quartz sand can be improved by reducing the oxide coatings on the quartz grains. In this direction, a study has been made to consider the possibility of coatings removal from quartz sand by attrition cleaning. Tests were conducted in a laboratory attrition cell at different values of operating parameters: suspension density, attrition time and stirrer speed. Indicators of attrition efficiency were the content of the particles – 0, 063 mm and content of main impurities (Al2O3, Fe2O3) removed through attrition process.

The quality of quartz sand can be improved by reducing the oxide coatings on the quartz grains. In this direction, a study has been made to consider the possibility of coatings removal from quartz sand by attrition cleaning. Tests were conducted in a laboratory attrition cell at different values of operating parameters: suspension density, attrition time and stirrer speed. Indicators of attritioning efficiency were the content of the particles - 0, 063 mm produced by abrasion of grain surfaces and content of main impurities (Al_2O_3, Fe_2O_3) removed through attrition process.

U ovom radu pod otpadom se podrazumijeva plastični otpad (lampioni). Ako se otpadom ne gospodari kako treba ili ga se nekontrolirano odlaže, on će onečistiti okoliš. Mnoge vrste plastike nisu biorazgradive bez obzira na uvjete u okolišu, barem ne u značajnoj mjeri, dok se neke vrste razgrađuju, ali sporo, pod uvjetom da su izložene povoljnom djelovanju zraka, vode i svjetla. Lampioni nisu biorazgradivi jer ni metal, niti plastika, niti parafin od kojih se sastoji lampion nisu biorazgradivi. Uzorak u provedenim ispitivanjima se sastoji od lampiona koji su izdrobljeni, prosijani i atrirani. Krupnije klase ne odgovaraju jer su prevelike za atricijsku ćeliju, a kod sitnijih klasa postoji velika mogućnost gubitaka materijala tijekom daljnih ispitivanja. Nakon postignutog raščina drobljenjem i odvajanja parafina i plastike pliva-tone separacijom na zrnu plastike zaostaje tanak sloj parafina. Hipoteza ovog rada je uklanjanje tog sloja parafina atriranjem. Uspješnost atricije razmatra se preko smanjenja sadržaja parafina. U svim pokusima došlo je do smanjenja masenog udjela parafina u koncentratu nakon atricije što nam govori da je hipoteza ovoga rada potvrđena., Under the term waste in this thesis, we assume plastic waste (lanterns). If waste is not properly managed or it is discarded it can pollute the environment. Regardless of environmental conditions a lot of plastic is not biodegradable, however, some types are degradable with favorable effects of air, water and light. Since metal, paraffin and plastic are not biodegradable, neither are lanterns. Used test sample is composed of crushed, sieved and attritioned lanterns. Coarse fractions are too big for atrittion cell so they don´t fit while smaller classes result in material loss during further testing. After liberation by crushing and separation of paraffin and plastic by sink and float process, a thin layer of paraffin remains on plastic grains. Attrition efficacy is considered through reduced content of paraffin. In all tests, decrease in mass portion of paraffin in concentrate after the attrition is determined, which tells us that the hypothesis of this thesis is accurate.