Cement, Energy and Environment

Leaching of heayy metals from the stabilized specimens The concentrations of Zn and Ni leaching from the WPS Specimens stabilized with cement were observed to be increasing with the increase in waste content (Figure 3). All specimens satisfied EPA limits for landfilling and the products could be classified as non– hazardous wastes. Because of the increasing pH values resulting from the cement used and the effects of the hydration products C-S-H and Ca (OH) 2 on the acidic conditions, the heavy metals could be kept in insoluble compound forms. This study indicated the increase of pH from 3.8 to 12 when WPS was missed with cement. At high pH values (pH>11 ), Zn could be in CaZn(OH) 6 2Hp form. Also it was observed that Ni was successfully stabilized using cement. In the WPS specimens stabilized with cement, pH value decreased with increasing amount of sludge causing an increase in heavy metal concentrations (Figure 3). The stabilizatiol) of Zn and Ni was realized with a control of the pH value. The furnace dust EAFD, was tried to be stabilized using cement, lime and a mixture of cement and lime at 1:1 ratio. The results are shown in Figure 4. The leaching values for Zn and Pb were lower when stabilized with the mixture compared with those obtained using only cement or only lime. When the EAFD content of the specimens were increased from 30 per cent to 40% an increase in leaching of Pb occurred. This was caused due to a drop in pH value at this level. The leaching of Pb increased from 0.11 to 1.52 when the pH value ' Table-2 Analyses of the waste oil Parametre Qty Allowed Limited Category I Category II Category Ill Arsenic ( As) 0.63 <5 5 >5 Cadmium (Cd) 0.20 <2 2 >2 Chromium (Cr) 9.66 <10 10 >10 Chlorine (CI) 48.66 <200 2000 >2000 Lead (Pb) 2.0 <100 100 >100 Toplam Halojenler 399.6 <200 2000 >2000 (mg/1) Polonium (Po) 10 <10 501 >50 Calorific value (kg) 26000 Table-3 Properties of the used tire Parameter % Carbon Hydrogen Nitrogen Sulphur Oxygen Zn Moisture Ash Calorific value (Kg.) decreased from 8.16 to 6.16. It was observed that the specimen containing up to 30 per cent EAFD could be made non– hazardous by using the cement– lime mixture. Second phase Characterization of waste oil and used tires The results of the analyses performed on waste oil are shown in Table-2 together with the category limits. Accordingly, the waste oil could be classified in Category II. There was no direct code applied for used tires in the regulation on the control of hazardous wastes and they 83.87 7.09 0.24 1.23 2. 17 1.52 0.62 4.78 37798 were considered in the category 16 01 - Wastes resulting during maintenance or disassembling of vehicles. The properties of the used tire are given in Table-3. Leaching of heavy metals from cements produced with alternative fuels The concentrations of heavy metals passing into the leaching liquid from the cement mortar specimens broken at the end of 28 days are shown in Figure 5. The specimens produced by using alternative fuels at 2 per cent and 16 per cent ratios complied with the heavy metals limits of EPA. Therefore, it was concluded that heavy metals 50 '\...- -