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    Coal flotation optimization using modified flotation parameters and combustible recovery in a Jameson cell
    (PERGAMON-ELSEVIER SCIENCE LTD, 2010) Vapur, Hueseyin; Bayat, Oktay; Ucurum, Metin
    This study discusses a new coal flotation optimization approach. It is conducted using modified flotation parameters and combustible recovery. The experimental work was evaluated in two stages. In the first stage, recoveries (1, 2, 3, 5 and 8 min of flotation times) of Jameson flotation operating parameters were fitted to first-order kinetic model, R = R(infinity) [1 - exp (-kt)] where R was recovery at t time, R(infinity) was ultimate recovery and k was the first-order rate constant to draw the time recovery curves in the experimental study. Two parameters, the ultimate recovery (R) and first-order rate constant (k), were then obtained from the model to fit an experimental time recovery curve. A modified flotation rate constant (K(m)) defined as product of R(infinity) and k, i.e., K(m) = R(infinity) * k, and selectivity index (SI) defined as the ratio of the modified rate constant of coal to the modified rate constant of ash (SI)=K(m) of Coal/K(m) of Ash), which could be collectively called "modified flotation parameters". It was used to determine of the sub and upper values of operation variables. In the second one, combustible recovery (%) and ash content (%) were used to optimization of the Jameson flotation variables and it was found that d(80) = 0.250 mm particle size, 1/1 vegetable oil acids/kerosene ratio, 20% solids pulp density, 0.600 L/min wash water rate and 40 cm downcomer immersion dept could be used to separate efficiently coal from ash. Final concentrate was obtained with 94.83% combustible recovery and 17.86% ash content at optimum conditions after 8 min flotation time. (C) 2010 Elsevier Ltd. All rights reserved.
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    Recovery of Silver from Waste Radiographic Films by Chemical Leaching
    (ASIAN JOURNAL OF CHEMISTRY, 2011) Arslan, Volkan; Ucurum, Metin; Vapur, Huseyin; Bayat, Oktay
    The major sources to recover silver are photo-processing solutions, spent rinse water, scrap film and scrap printing paper. As much as 80 % of the total silver processed for black and white positives and almost 100 % of the silver processed in colour work will end up in the fixer solution. The waste radiographic films used in the experiments were taken from Cukurova University, Balcali Hospital, Adana, Turkey and cut into small pieces. The film pieces (1-9 g) were boiled with 100 mL of various quantities of oxalic acid, nitric acid and sodium hydroxide solutions for about 2.5, 5.0, 7.5 and 10 min at boiling temperature (congruent to 97 degrees C). The aim of the study is to recover silver from waste radiographic films by HNO(3) leaching. To optimize the results of the experimental work, variance analysis was used. The statistical tests (F-tests) showed that nitric acid gave the best results compared with the other agents. Under optimum leaching conditions (radiographic films quantity, 50 g/L; nitric acid concentration, 30 g/L; stirring speed, 180 rpm; leaching time, 15 min) 89 % silver recovery was obtained.