E.A. ABDEL-AAL Central Metallurgical Research and Development Institute, P.O. Box 87, Helwan, Cairo, Egypt.

M.M. RASHAD Central Metallurgical Research and Development Institute, P.O. Box 87, Helwan, Cairo, Egypt.

HYDROMETALLURGICAL PROCESSING OF EGYPTIAN MAGNESITE ORE WITH NITRIC ACID

Egyptian magnesite ore (43.32% MgO) from the Eastern Desert was leached with aqueous nitric acid and the following optimum conditi-ons of leaching were determined: ore particle size 100% -0.5 mm, temperature 50°C, leaching time 30 min, HNO3 to MgO molar ratio 1.05, and liquid/solid ratio of 2.8:1.0 ml/g. These conditions lead to recovery of 96.2% MgO. Resultant liquor was first treated with stoichiometric amount of sulfuric acid in order to precipitate calcium ions and then was neutralized with MgO. Purified magnesium nitrate solution was evaporated and magnesium nitrate crystals of 99.7% purity were obtained. Block flowsheet of this process was proposed.

Publication language: English

Pages: 7-17

N.A. ABDEL-KHALEK Central Metallurgical Research and Development Institute, CMRDI, P. O. Box 87, Helwan, Cairo, Egypt.

A.M.A. OMAR Egyptian Petroleum Research Institute, Cairo, Egypt.

Y. BARAKAT Egyptian Petroleum Research Institute, Cairo, Egypt.

FLOTATION OF EGYPTIAN PETROLEUM COKE USING 4-PHENYL DODECYL BENZENE

This paper aims to study monoisomeric 4-phenyl dodecyl benzene, a synthetic anionic surfactant as a collector in the flotation of an Egyptian petroleum coke to minimize its ash content as well as its heavy metals to be suitable for manufacture of electrodes. The structure of the surfactant was iden-tified by IR, NMR and mass spectra. The surface properties and the thermodynamic characters of this surfactant were also studied. With raising the temperature from 25 to 55°C the value of critical micelle concentration (cmc) increases slightly while the surface excess concentration at the surface saturation (Gmax) shows a small reduction. This is accompanied by an increase in area occupied per molecule at the interface at surface saturation (Amax). The results reveal also that the values of the free energy change upon adsorption (DGads) are all negative at different temperatures. This indicates that the adsorption of this collector at the aqueous solution/air and the aqueous solution/solid interface is spontaneous. The flotation tests were carried out using a laboratory "Denver" flotation cell at 10 wt.% solids using sodium silicate as a depressant. Different parameters affecting flotation of coke such as the dosage of the surfactant, its mode of addition, dosage of depressant and pH, were studied. The results showed that at the optimum conditions for flotation a coke concentrate assaying only 0.19% ash in comparison with 1.38% in the feed samples is obtained. At the same time, the tail fractions had high ash contents (12.5%) and it was very contaminated with heavy metals. The flotation results are in good agreement with that of the surface properties and the thermodynamic characters of the surfactant.

Publication language: English

Pages: 19-30

Y.M.Z. AHMED Central Metallurgical Research and Development Institute, P.O. Box 87, Helwan, Cairo, Egypt.

M.H. KHEDR Central Metallurgical Research and Development Institute, P.O. Box 87, Helwan, Cairo, Egypt.

O.A. MOHAMED Central Metallurgical Research and Development Institute, P.O. Box 87, Helwan, Cairo, Egypt.

M.E.H. SHALABI Central Metallurgical Research and Development Institute, P.O. Box 87, Helwan, Cairo, Egypt.

THE ROLE OF CALCIUM HYDROXIDE IN THE PRODUCTION OF IRON OXIDE (MILL SCALE) PELLETS

Mill scale which is a valuable secondary raw material produced from the rolling of steel sheets in steel making process, can be agglomerated by using the pelletizing technique for the production of iron oxide pellets. The physicochemical properties of iron oxide pellets produced from mill scale were found to be improved with calcium hydroxide addition. The amount of calcium hydroxide added is varied from 0.5-4%, where the green, dry and indurated mill scale pellets properties were studied and the results of the experiments can be summarised as follows: 1. As the amount of calcium hydroxide added increased the productivity, average drop number (the resistance of pellets to be broken or cracked when dropped from 30 cm hight) and compressive strength of green mill scale pellets increased. 2. The compressive strength and average drop number of dried pellets increased with the increase of both the amount of calcium hydroxide and the drying temperature. 3. The maximum value of compressive strength of indurated pellets was attained at 4% of calcium hydroxide addition followed by induration at 1300 °C. 4. The reducibility of the indurated pellets was highest with 0.5% calcium hydroxide and decreased with increasing the amount of calcium hydroxide. While on increasing the firing temperature from 1000 to 1300°C for pellets containing 4% of calcium hydroxide, the reducibility decreased. 5. The compressive strength of reduced mill scale pellets increased with increasing both the amount of calcium hydroxide and firing tem-peratures for pellets containing 4% of calcium hydroxide. 6. The reduction process of mill scale pellets containing 4% of calcium hydroxide was controlled by combined mechanism for both the initial and final stages of reduction.

Publication language: English

Pages: 31-41

A.M. AMER Geology Dept., Faculty of Science, Alexandria University, Moharem Bey, Alexandria, Egypt.

I.A. IBRAHIM Central Metallurgical R & D Institute, Helwan, Cairo.

BACTERIAL LEACHING OF COMPLEX SULPHIDE ORE FROM AKAREM AREA, EGYPT

Bacterial leaching of copper, nickel and cobalt from a complex sulphide ore was studied in shake flask experiments using Thiobacillus ferrooxidans at 20 °C. After 20 days of leaching all 90% of Cu, 70% Co and 95% Ni was extracted from the ore. For all sulphide minerals present in the studied ore samples, the data emphasizes that the fastest leaching rates are achieved under oxidizing conditions and low pH (< 2.5) values, where a considerable portion of ferric iron remains in the solution.

Publication language: English

Pages: 43-50

Tomasz CHMIELEWSKI Zaklad Hydrometalurgii, Instytut Chemii Nieorganicznej i Metalurgii Pierwiastkow Rzadkich Politechniki Wroclawskiej, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw.

Jerzy WODKA Zaklad Hydrometalurgii, Instytut Chemii Nieorganicznej i Metalurgii Pierwiastkow Rzadkich Politechniki Wroclawskiej, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw.

RECOVERING OF SILVER AND COPPER FROM SILVER-BEARING WASTE SLUG BY AMMONIA LEACHING

The results are presented on hydrometallurgical recovering of silver and copper from silver-bearing waste slag containing 0,95–4% Ag, 0,5–2% Cu, and about 50 ppm Au. The waste slag originates from metallurgical processing of anodic slimes from copper electroraffination. The ammonia-based method was proposed involving the oxygen pressure leaching in NH3 + NH4+ solution and then selective hydrothermal precipitation of silver and copper with hydrogen under pressure. This method appeared to be efficient while the concentration of metals (Ag, Cu) in the leaching solution can be substantially elevated in a multiple leaching with circulating leaching solution.

Publication language: Polish

Pages: 51-61

Maria C. COSTA Universidade do Algarve, UCTA, Campus de Gambelas, 8000 Faro, Portugal.

HYDROMETALLURGY OF GOLD: NEW PERSPECTIVES AND TREATMENT OF REFRACTORY SULPHIDE ORES

In the last two decades a considerable number of new hydrometallurgical processes have been developed and implemented in gold industry allowing the economical treatment of increasingly complex and lower grade ores as well as refractory ores. As a result, all over the world the production of gold has almost doubled in the last 20 years. In order to overcome the environmental problems caused by cyanidation, new leaching agents have been searched and new leaching techniques, particularly heap leaching, were developed for the treatment of low grade ores. The developments related with gold extraction from pregnant solutions include, carbon-in-pulp, carbon-in-leach processes, the use of resins and solvent extraction techniques. A considerable effort has also been made to treat refractory ores. With that purpose pressure oxidation, bacterial oxidation and more recently electro-oxidation have been investigated with good results as alternative techniques to the classical oxidative roasting. In this paper those developments are revised and considerable attention is given to the electrochemical treatment of refractory sulphide ores.

Publication language: English

Pages: 63-72

Dereviankin Y.

Ivanova N.

INVESTIGATION OF A POSSIBILITY OF AN ACCOMPANYING RECOVERY OF GOLD-BEARING CONCENTRATE OF HEAVY MINERALS FROM SANDY-GRAVEL MATERIALS

The data on accompanying recovery of the concentrate of heavy minerals crush-sorting factorics of Belarus, which contains gold are described Sands of 5 mm fraction of sand-gravel deposits was the raw material for investigation. we used VTsS-12,5 the vibrator-cetntrifugal separator (Russia) and the Knelson-30 concentrator. The concentrates of these separators were rinsed again by means of the Knelson-7,5, or the UOS-11. Methods of mineralogical analysis, gravity, magnetic and electrostatic enrichment were used at the final stage. It was shown that it is possible to carry out the accompanying recovery of valuable minerals by ecologically clean gravity method from quarternary sands. The size distribution of native gold, received in the course of tests was investigated. It was shown that the main quantity of gold was in the fraction size smaller than 0,15 mm. Taking into account a small size of gold grains, as the main accompanying component, its recovery is possible by using of centrifugal separators. The gold content in the raw material varied with in a very wide range (5 to 1550 mg/m3). The gold recovery into the concentrate varies widely as well. Nevertheless, the average gold recovery reached 57.7 and 66.6% for VTsS-12,5 and Knelson-30 separator, respectively.

Publication language: Russian

Pages: 73-82

Ludwik DOMKA Zaklad Chemii Metaloorganicznej, Wydzial Chemii, Uniwersytet im. Adama Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznan.

COMPARISON OF PHYSICOCHEMICAL PROPERTIES OF NATURAL CHALKS FROM POLISH DEPOSITS AND THEIR SIGNIFICANCE FOR ELASTOMER PROCESSING

The possibility of applying chalks from Polish deposits in Kornica, Mielnik, Dzialoszyn, and Zabierzow as fillers of butadiene-styrene rubbers was tested.
Chemical composition of the chalks and their basic physicochemical properties (specific surface, bulk density, packing density and others) were determined. The chalks were modified with various coupling and proadhesive compounds. Chalks modified with tetrabutylammonium chloride or izostearoyl titanate were most effective in improving principal strength parameters (modules and tensile strength) of SBR type vulcanizates.

Publication language: Polish

Pages: 83-88

Tadeusz GLUBA Politechnika Lodzka, Wydzial Inzynierii Procesowej i Ochrony Srodowiska, ul. Stefanowskiego 12/16, 90-924 Lodz.

Andrzej OBRANIAK Politechnika Lodzka, Wydzial Inzynierii Procesowej i Ochrony Srodowiska, ul. Stefanowskiego 12/16, 90-924 Lodz.

ANALYSIS OF GRANULATION OF FINELY GROUND CHALK OF DIFFERENT PARTICLE SIZE DISTRIBUTION

The pelletization of chalk powder of different grain composition was analyzed. Investigations were carried out in a batch granulator 0.34 m in diameter and 0.41 m long at a constant rotational speed of the drum 0.5 s–1 and constant feeding of the apparatus with granular material equal 0.1 of the inner volume. The process of granulation was carried out batch-wise at a constant moisture content of the feed but at variable conditions of feed wetting. The effect of process variables and particle size distribution on the size distribution of the granulated material was estimated.

Publication language: Polish

Pages: 89-98

Ali GUNEY Istanbul Technical University, Mining Faculty, Mineral Processing Section, 80626 Maslak, Istanbul, Turkey.

Suna ATAK Istanbul Technical University, Mining Faculty, Mineral Processing Section, 80626 Maslak, Istanbul, Turkey.

SEPARATION OF CHROMITE FROM OLIVINE BY ANIONIC COLLECTORS

Chromite is concentrated mostly with shaking tables and spirals. Flotation can be considered as a leading process to beneficiate the fine chromite which cannot be enriched by gravity separation. Because of the complex nature of chromite and olivine which is the most abundant adjoininig mineral, the type of collector is very important in this flotation. After examination of the effect of sodium oleate on chromite and olivine by adsorption studies and electrokinetic mobility measurements, sodium oleate and other anionic collectors were used in the chromite flotation. Flotation results showed that some special collectors such as modified fatty acid and alkyl phosphate are more effective on the separation of chromite from olivine.

Publication language: English

Pages: 99-106

Jan GUSPIEL Instytut Metalurgii i Inzynierii Materialowej Polskiej Akademii Nauk, Krakow, ul. Reymonta 25.

MgO samples of different mean grain sizes (3-55 mm)cintroled by the sintering parameters were used determine the specific dissolution rate of this oxide in 0.5 M H2SO4 at 10°C (the activation region), by the rotating disk technique. The grain sizes have been found to be dominant physical property of samples influencing the kinetics and rate of dissolution process. Experimentally determined specific dissolution rate follows the equation jr = 5.2.10–3Sz–1/2 + 1.8.10–9[mol.cm–2 .s–1], where Sz is the average area of the cross-section of a single grain [cm2]. Increasing average grain size in the 3–55 mm range reduced the specific dissolution rate about 9 times, without affecting the calculated values of the reaction order and activation energy of the reaction of dissolution.

Publication language: Polish

Pages: 107-114

Mariusz A.WOJCIK University of Mining & Metallurgy, Faculty of Ceramics & Materials Engineering, Al. Mickiewicza 30, A-3, 30-059 Cracow, Poland.

Tomasz GAJDA University of Mining & Metallurgy, Faculty of Ceramics & Materials Engineering, Al. Mickiewicza 30, A-3, 30-059 Cracow, Poland.

Julian PLEWA Fachhochschule Munster, Fachbereich Chemieingenieurwesen Stegerwaldstrasse 39, D-48565 Steinfurt, Germany.

Horst ALTENBURG Fachhochschule Munster, Fachbereich Chemieingenieurwesen Stegerwaldstrasse 39, D-48565 Steinfurt, Germany.

Ansgar LUTTERMANN Fachhochschule Munster, Fachbereich Chemieingenieurwesen Stegerwaldstrasse 39, D-48565 Steinfurt, Germany.

Viliam FIGUSCH Academia Istropolitana, Klariska 5, 810-00 Bratyslava, Slovakia.

Miroslav HAVIAR Academia Istropolitana, Klariska 5, 810-00 Bratyslava, Slovakia.

EFFECT OF SELECTED PARAMETERS ON GRINDING PROCESS OF ALUMINA IN THE ROTARY-VIBRATION MILL

The effect of selected parameters on grinding process of two types of alumina in the rotary-vibration mill (RVM) was presented. The effect of mutual relation between filling, media and suspension ratios as well as the size of grinding media, time and frequencies of chamber mill on grinding of alumina was investigated and the kinetics of grinding of this materials was shown. Investigations revealed that it is possible to obtain fine alumina powders of alumina characterizing with d50 approximately 3 mm and d90 close to 10 mm during about 60 minutes of grinding in RVM. Also, the effect of mentioned above parameters on physical properties of moulders prepared from ground alumina powders was shown. The relations between grinding time and green and fire density and shrinkage was also presented and discussed. The results revealed that longer grinding time inreased both green and fire density and shrinkage of moulders.

Publication language: English

Pages: 115-124

Wladyslaw JANUSZ Zaklad Radiochemii i Chemii Koloidow, Wydzial Chemii, UMCS, Lublin.

PARAMETERS OF DOUBLE ELECTRIC LAYER AT THE INTERFACE ZrO2–AQUEOUS SOLUTION OF NaCl BY THE NUMERICAL OPTIMIZATION METHOD

The results presented show that for commercial ZrO2 the adsorption of the electrolyte ions is connected not only with surface groups but also with ion exchange reactions. The latter do not change the surface charge. Theoretical description of ion adsorption processes, based on the site binding theory, renders well only the surface charge vs. pH. Contrary to the above, the adsorption of background electrolyte ions does not agree with theoretical calculations. To estimate participation of background electrolyte ions in the surface charge formation and correct adsorption measurements, the ion or isotope exchange processes between surface and solution must be considered. The ZrO2–aqueous solution system is very sensitive to the contamination originated from the preparation of the oxide.

Publication language: Polish

Pages: 125-135

Andrzej JAROSINSKI Instytut Chemii i Technologii Nieorganicznej Politechniki Krakowskiej, 31-155 Krakow, ul. Waroszawska 24.

Czeslaw OSTROWSKI Instytut Chemii i Technologii Nieorganicznej Politechniki Krakowskiej, 31-155 Krakow, ul. Warszawska 24.

EFFECT OF PORTLAND CEMENT ON STRENGTH DEVELOPMENT OF PHOSPHOANHYDRITE-POZZOLANA CEMENT

The paper is a part of the research on a complex alternative technology of apatite phosphogypsum (PG) obtained during the production of phosphoric acid from Kola apatite, on rare earth concentrate and phosphoanhydrite cement with the recovery of phosphate compounds. The effect of Portland cement on mechanical properties of phosphoanhydrite-pozzolana cement has been determined. The samples of binder were prepared with phosphoanhydrite and a constant amount of fly ash while the content of Portland cement amounted from 5 to 20%. Maximum strength of the discussed cement was reached for Portland cement addition in the amount of 20 wt. %, after 90 days. The presence of ettringite in the tested samples was confirmed by means of chemical and X-ray analysis. The change of mechanical properties of the above cements is connected with the formation of ettringite and its decomposition during the hydration process of binder. It was found that the change of linear expansion is also connected with the content of the ettringite phase in binders.

Publication language: English

Pages: 137-143

Barbara KOLODZIEJ Instytut Chemii Nieorganicznej i Metalurgii Pierwiastkow Rzadkich Politechniki Wroclawskiej, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw.

Zbigniew ADAMSKI Instytut Chemii Nieorganicznej i Metalurgii Pierwiastkow Rzadkich Politechniki Wroclawskiej, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw.

LEACHING OF NOBLE METALS FROM ORES BY THIOUREA

The aim of the present work was to investigate the properties of leaching by means of thiourea for: It was found that the application of thiourea to the leaching of carbonate ore is very efficient. After 3 hours of leaching at 18°C the 92.5% and 92% of gold, platinium and palladium, respectively, was extrcated. In the case of gold concentrate originating from refractory ores the preliminary reductive leaching was used. In the essential leaching by thiourea the 47% increase of leaching of gold was observed. After 20 hours of leaching at 18°C the 68%, 98% and 99% gold, platinium and palladium was leached.

Publication language: Polish

Pages: 145-155

Zygmunt KOWALSKI Cracow University of Technology, Institute of Chemistry and Inorganic Technology, Warszawska St. 24, 31-155 Cracow.

METHODS OF UTILISATION OF WASTE CALCIUM FLUORIDE SLURRY

Utilisation methods of waste calcium fluoride slurry into pulver calcium fluoride and synthetic fluorspar are presented. Synthetic fluorspar could change the way the natural raw material are used in metallurgical industry. To obtain grained synthetic fluorspar calcium fluoride, slurry is calcinated in a rotary kiln at temperature 900–1100K. Grain size and compression strength is strongly depended from calcination time and temperature. Another alternative is using of the briquetting in this process. All utilisation methods were compared.

Publication language: English

Pages: 157-164

Andrzej KRYSZTAFKIEWICZ Instytut Technologii i Inzynierii Chemicznej, Politechnika Poznanska, 60-965 Poznan.

Bozena RAGER Instytut Technologii i Inzynierii Chemicznej, Politechnika Poznanska, 60-965 Poznan.

Teofil JESIONOWSKI Instytut Technologii i Inzynierii Chemicznej, Politechnika Poznanska, 60-965 Poznan.

PRODUCTION OF SILICATE PIGMENTS EXHIBITING HIGH GRADES OF DISPERSION.

Procedures for production of red and green pigments were presented, based on precipitation reactions in sodium metasilicate solutions supplemented with iron (III) or chromium (III) salts.
The studies aimed at obtaining pigments of formulae xFe2O3·ySiO2·zH2O and xCr2O3·ySiO2·zH2O, respectively. Moreover, principal physicochemical parameters of the precipitated pigments were established, including bulk and packing densities, capacities to absorb water and paraffin oil, size and morphology of pigment particles. The latter variables were examined using electron microscopy. The studies aimed also at defining if the pigments can be used as fillers and carriers in oil paints.

Publication language: Polish

Pages: 165-173

Janusz J. LEKKI Katedra Przerobki Kopalin i Utylizacji Odpadow, Politechnika Slaska, ul Akademicka 2, 44-101 Gliwice.

FLOTOMETRIC EVALUATION OF NATURAL, COLLECTORLESS AND XANTHATE FLOTATION OF SULFIDE MINERALS

On the basis of metastable equilibria for sulfide minerals, the natural, collectorless and xanthate hydrophobicity as well as floatability were defined. Assuming that the collectorless hydrophobicity is determined by oxidation products, that is sulfur or covellite occupying the area on the surface which is proportional to the stoichiometry of the anodic reactions, the maximum diameter of particles which can float was calculated. Utilizing Wark’s data indicating that the contact angle for sulfide mineral in xanthate solutions is 60° and 70° for systems with dixanthogen, the diameters of the floating particles were calculated. It was found that there is a linear correlation between the calculated and experimental values of the maximum diameter of a floating particle and the correlation coefficient is equal to 0.99 when the particles are subjected to flotation individually. The relationship between calculated values of the maximum diameter of floating particles (D10, cm) and the experimental values for collectorless flotation of an ensemble of particles (Dz, cm) is, (D10 – 0.01)2 = 0.415Dz and its accuracy is ±0.003, while for the xanthate and dixanthogen flotation the equation assumes the form, (D10 – 0.03)2 = 0.144Dz with the accuracy of ±0.003. These equations eliminate the influence of aggregation of particles and allow to calculate the flotometric index L50, where L50 = Dzr´ and r´ stands for the particle density in water. The floatability of an ensemble of particles determined in a Hallimond tube and characterized by L50 index results from the thermodynamics of the flotation system and the interfacial energies of the three interfaces involved.

Publication language: Polish

Pages: 175-196

Andrzej LUSZCZKIEWICZ Politechnika Wroclawska, Instytut Gornictwa, Zaklad Przerobki Kopalin i Odpadow, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw.

Antoni MUSZER Uniwersytet Wroclawski, Instytut Nauk Geologicznych, Zaklad Geologii i Dokumentowania Zloz, Pl. Maksa Borna 9, 50-204 Wroclaw.

GOLD IN MINE WASTES FROM ZLOTY STOK REGION (SW POLAND)

The Zloty Stok gold mines, until their closure in 1962, were among oldest in Europe. The gold mining industry operating in the region through the last ten centuries left many heaps of mine and foundry wastes behind. Mineralogical and chemical compositions of arsenic ore sample taken from the biggest in Zloty Stok area heap of mine waste, were investigated. The mine waste assaying 1.2–1.7ppm Au was subjected to gravity separation and the slurry from gravity separation was directed to flotation tests. The gravity and flotation concentrates contained 34 and 18ppm of gold, respectively, were obtained. It was determined that maximum content of gold in the arsenic minerals concentrate cannot be greater than 40 ppm. The results of these experiments revealed that a part of gold in the heap material is disseminated in arsenic minerals and the remaining part of gold is liberated as a result of weathering. Certain amount of gold is probably liberated from arsenic minerals lattice forming very fine particles which are too small for successful flotation.

Publication language: Polish

Pages: 197-209

J.D. MILLER Department of Metallurgical Engineering University of Utah, Salt Lake City, Utah 84112, USA.

J. HUPKA Department of Chemical Technology, Technical University of Gdansk, 80-952 Gdansk, Poland.

D. HALBE Department of Metallurgical Engineering University of Utah, Salt Lake City, Utah 84112, USA.

J. NALASKOWSKI Department of Chemical Technology, Technical University of Gdansk, 80-952 Gdansk, Poland.

N. LIU Department of Metallurgical Engineering University of Utah, Salt Lake City, Utah 84112, USA.

RECOVERY OF FOSSIL RESIN FROM COAL FINES

Processing technology for fossil resin recovery from the Wasatch Plateau coal deposits (Utah, USA) is described. It was found during traditional materials handling of the run-of-mine coal that the fossil resin tends to concentrate in coal fines fraction. The influence of frother type, pulp concentration and pH on concentrate grade and recovery was examined during flotation of < 650 mm (–28 mesh) and < 150 mm (–100 mesh) coal fractions. The resin was extracted from the wet flotation concentrate using a heptane-in-water emulsion. The extraction rate and resin recovery were improved when the emulsion was stabilized with surfactants. The surfactant type (anionic, cationic and nonionic) had minimal influence on the extraction performance.

Publication language: English

Pages: 211-219

M. NIEWIADOMSKI Department of Chemical Technology, Technical University of Gdansk, 80-952 Gdansk, Poland.

J. HUPKA Department of Chemical Technology, Technical University of Gdansk, 80-952 Gdansk, Poland.

R. BOKOTKO Department of Chemical Technology, Technical University of Gdansk, 80-952 Gdansk, Poland.

J.D. MILLER Department of Metallurgical Engineering University of Utah, Salt Lake City, Utah 84112, USA.

FLOTATION OF FINE COKE PARTICLES FROM FLY ASH

Fine coke particles were separated from fly ash in a laboratory flotation cell. Almost 90% of particles by number were below 10 mm and one third of them was less than 2 mm. Fly ash was sampled directly from a surge bin in a power plant and from a refuse dump area. Kerosene and Diesel oil were compared as collectors, and MIBC and polyglycol – based agents – were used as frothers. The best separation coefficient of 0.8 was obtained for 18 kg/t of Diesel oil and 9 kg/t of commercial frother based on polyglycol.

Publication language: English

Pages: 221-228

Gulhan OZBAYOGLU Middle East technical University, Mining Eng. Dept., Ankara, Turkey.

CORRELATION OF NATURAL HYDROPHOBICITY OF COAL WITH ITS PETROGRAPHIC COMPOSITION

The electrokinetic potential variation with the pH of the parent Çay coal seam appeared to be the result of the combined effects of the three (vitrain, durain, fusian) lithotypes. Vitrain was found to be the highest naturally hydrophobic lithotype as a result of contact angle measurements. This observation was supported by the findings during adsorption tests. On the basis of electrokinetic measurements, contact angle and adsorption tests, a correlation was established between the natural hydrophobicity of coals and their petrographic composition. Vitrain with a composition of mainly vitrinite was the most hydrophobic lithotype. The natural hydrophobicity of channel coals improve with the increase in their vitrinite contents.

Publication language: English

Pages: 229-234

Jerzy SABLIK Glowny Instytut Gornictwa, 40-166 Katowice

DEPENDENCE OF COAL SLURRIES FLOTABILITY ON THE MEAN CRITICAL SURFACE TENSION OF COAL

Investigation result of dependence of coal slurries flotability, the measure of which was the recovery of combustible, on mean critical surface tension definied as such a border value of the methanol-water solution surface tension, that a particle placed on the surface sink, are presented. It was found that the equation describing the phenomenon was exponential and the recovery of combustible depending on decreases from 90% for middle rank coal to 0% for low rank coal. Making advantage of these results and some results published earlier, the analysis for reasons for the differentiation of coals standard flotability has been conducted.

Publication language: Polish

Pages: 235-240

Teresa SUDOL Uniwersytet Opolski, Instytut Chemii, 45-291 Opole, ul. Oleska 48.

Teresa FARBISZEWSKA Uniwersytet Opolski, Instytut Chemii, 45-291 Opole, ul. Oleska 48.

Jadwiga FARBISZEWSKA-BAJER Uniwersytet Opolski, Katedra Inzynierii Procesowej, 45-365 Opole, ul. Dmowskiego 7–9.

MECHANISM OF CHEMICAL CHANGES ON THE PROCESS OF BIODEGRADATION OF FATS

The analysis of biodegradation mechanisms of fats by using autochthonous bacteria strains has been presented. It was found that in 30 days 62% of aliphatic compounds were removed. There was a noticeable decrease of the content of the aliphatic coal components in favour of olefin component and a great amount of carboxylic acid was formed. This caused the diminishing of pH to 3.5 and the investigated process was inhibited.

Publication language: Polish

Pages: 241-246

R. TOMANEC Faculty of Mining and Geology, Djušina 7, P.O. Box 162, Belgrade, Yugoslavia.

S. POPOV Faculty of Mining and Geology, Djušina 7, P.O. Box 162, Belgrade, Yugoslavia.

D. VUCINIC Faculty of Mining and Geology, Djušina 7, P.O. Box 162, Belgrade, Yugoslavia.

P. LAZIC Faculty of Mining and Geology, Djušina 7, P.O. Box 162, Belgrade, Yugoslavia.

VERMICULITE FROM KOPAONIK (YUGOSLAVIA) CHARACTERIZATION AND PROCESSING

In the last few years, many nonmetallic minerals, including vermiculite, have been subject to geologic and mineral processing investigation in Yugoslavia. In this study, the identification of vermiculite from the Kusici–Kopaonik deposit (Yugoslavia) was carried out using microscopy, DTA, TGA, X-ray and IR spectroscopy methods. In addition, small amount of chlorite was identified in the examined sample by X-ray method. Expanding properties of different size fraction of vermiculite was performed, followed by the use of stereomicroscope and by measurement of the volumetric mass before and after the expansion. The maximum expansion was accomplished at 910–920°C. The IR spectra showed that heating of vermiculite at this temperature (about 900°C), for only 7 minutes, resulted in notable reduction of absorption bands characteristics for water, indicating the important water loss from the mineral.

Publication language: English

Pages: 247-254

Piotr WODZINSKI Katedra Aparatury Procesowej Politechniki Lodzkiej, ul. Wolczanska 175, 90-924 Lodz.

ON THE PROBABILITY OF SEPARATION BY SCREENING

The present paper describes the process of screening of granular material using the theory of probability. The basic parameter, which is considered in the paper, is the probability of screening also called the screening number. In general, the screening number includes all basic parameters which determine the process of screening of loose materials and is an independent variable. In this paper theoretical bases of the screening number are presented and methods of its determination described. Attention is paid to this new method of describing screening machines.

Publication language: Polish

Pages: 255-265

Ahmed YEHIA Central Metallurgical R & D Institute, P. O. Box 87, Helwan, Cairo, Egypt.

Suzan S. IBRAHIM Central Metallurgical R & D Institute, P. O. Box 87, Helwan, Cairo, Egypt.

RECYCLING OF SILICA DUST – BYPRODUCTS FOR Si-SEMICONDUCTOR INDUSTRY

Beneficiation process has been developed to provide selective separation of silica dust material. This material is produced from the furnaces of silicon metal and ferrosilicon and considered to be of little or even of no value material. Cyclone classification of original sample, 90% – 15 mm in size, followed by froth flotation using cheap local collectors was carried out to remove the unburned and the iron contaminants. Dewatering tests were also carried out for the diluted pulp concentrate. A simple flowsheet has been suggested to produce bright silica fine product exceeded 99.5% SiO2, from starting material with 95.5%.

Publication language: English

Pages: 267-274