A kinetic study of oxidized copper ore in ammonium chloride solutions (1999) Volume(issue) 3(2): 55-65.

Yartaşı, M. Çopur, M. M. Kocakerim, C. Özmetin, and H. Temur

University of Atatürk, Engineering Faculty, Chemical Engineering Department, Erzurum, Turkey

 In the present work, the dissolution of an oxidized copper ore in ammonium chloride solutions was studied. In the experiments, ammonium chloride concentration, reaction temperature, solid-to-liquid ratio, particle size, and stirring speed were chosen as process parameters. It was observed that the decrease in solid-to-liquid ratio and particle size, and the increase in the reaction temperature and solution concentration increased the dissolution rate. It was found that the stirring speed has no significant effect on the dissolution rate. The reaction kinetics of the copper ore according to the heterogeneous and homogeneous reaction models was examined and it was found that the dissolution proceeded in two steps; the first step controlled by surface chemical reaction and the second step controlled by diffusion through the ash layer. The activation energies for the first and second steps were found to be 40.70 and 13.29 kJ.mol, respectively.

Kinetics for desulfurization of Şırnak asphaltite with aqueous hydrogen peroxide (1999) Volume(issue) 3(2): 67-75.

R. Boncukçuoğlu¹, M. M. Kocakerim², and M. Çopur²

2Atatürk University, Department of Chemical Engineering, 25240 Erzurum, Turkey

In this study, Şırnak (in Turkey) asphaltite was leached with aqueous hydrogen peroxide-sulfuric acid solutions. The effect of process parameters, such as particle size, H₂O₂ concentration, H₂SO₄ concentration and temperature, on the leaching of sulfur were investigated. The leaching rate of pyritic sulfur was very fast in the first 30 minute experimental period. It was found that the leaching of pyritic sulfur had fitted pseudo-homogenous second order reaction kinetics, and the mathematical model including process parameter was determined as follows:

X_B/(1-X_B) = 98632.7 (D)^-2.88 (C_p)^1.84 (C_A)^-2.34 exp(-18625/RT) (t)^0.7

An optimization study of leaching of oxidized copper ore in NH₃ solutions (1999) Volume(issue) 3(2): 77-84.

A. Yartaşı, M. Çopur, C. Özmetin, M. M. Kocakerim, and H. Temur

Atatürk University, Engineering Faculty, Chemical Eng. Dept. 25240 Erzurum, Turkey

The Taguchi method was used to determine optimum conditions for the dissolution of oxidized copper ore in NH₃ solutions. The experimental parameters and their ranges were between 12-55 ^oC for reaction temperature, 0.1-0.3 g.mL^-1 for solid-to-liquid ratio, 2-10 M for ammonia concentration, 15-120 min for reaction time, and 300-900 rpm for stirring speed, 1000 - 300 m m for particle size. The optimum conditions for these parameters were found to be 55 ^oC; 0.1 g.ml^-1; 6M; 90 min; 300 min^-1 and 300m m respectively. Under these optimum conditions, the dissolution of the oxidized copper ore in NH₃ solutions was approximately 90 %. In addition, some experiments were performed to find alternative parameter levels, and dissolution values were given so that it can be used in the industrial applications.

The flora of Çamburnu (Trabzon-Sürmene) national park in Turkey (1999) Volume(issue) 3(2): 85-88.

E. Nural, A. H. Gündoğmuş, and E. Sesli

Karadeniz Tchnical University, Department of Science Education, 61335, Akçaabat, Trabzon, Turkey

During the study which was performed in Çamburnu national park some plant specimens were collected. After the examinations, 33 plant species belonging to 25 families were identified.

Dissolution of braunite in HCl solutions (1999) Volume(issue) 3(2): 89-94

C. Özmetin¹, A. Yartaşı¹, M. M. Kocakerim¹, anad A. Ekmekyapar²

2 Inönü University, Eng. Faculty Chem. Eng. Depart, Malatya, Turkey

Manganese, a less available element in the earth, is an important substance used widely, especially in metallurgy and chemical industry. Manganese compounds are produced by a number of physical and chemical processes from many manganese ores which are present in nature. Braunite is one of the ores used for this purpose.

In this investigation the dissolution of Braunite from Oltu, Erzurum-Turkey in hyrochloric acid solutions was studied. In the experiments, particle size, acid concentration, stirring speed and reaction temperature were chosen as parameters. It was observed that the dissolution rate increased with increasing acid concentration and reaction temperature, and with decreasing particle size, while no pronounced effect of stirring speed was observed.

Experimental calculation in chemistry education (1999) Volume(issue) 3(2): 95-98

M. M. Küçük

Education Faculty, Y. Yıl University, 65080 Van, Turkey

This article is specifically consideration with the application of the experimental calculation or stoichiometric calculation in chemistry education. In General Chemistry Laboratory, NaHCO₃(s) was given to different student groups. NaHCO₃ (s) was then heated and predict the products of the decomposition. It was found that NaHCO₃ (s) decompose to Na₂CO₃ (s) , CO₂ (g) and H₂O (g). End of the experiments, student groups selected have leaded to apply the concept in the scientific analysis of a chemical problem.

 Removal of iron from solutions containing Fe⁺² by different adsorbants (1999) Volume(issue) 3(2): 99-108

O. Laçin¹, A. Ekmekyapar², and R. Gül³

2İnönü University, Department of Chemical Engineering, Malatya, Turkey

3Atatürk University, Department of Civil Engineering, Erzurum, Turkey

In the present study, removal of iron from the soil and activated soil samples by means of adsorption has been investigated. In addition, suitability of adsorption to Freundlich and/or Langmuir isotherms has been concluded. The contact filtration method was applied using Pumice, Tonsil, Mosaic and Bensan activated soils as adsorbents. The effect of Fe⁺² concentration, pH, resistant time and amount of adsorbents on the adsorption have been extensively investigated.