Most cited papers

Preparation of silver nanoparticles via chemical reduction and their antimicrobial activity
Szczepanowicz, K., Stefańska, J., Socha, R.P., Warszyński, P
Physicochemical Problems of Mineral Processing 45, 2010, 85-98

A simple and economic method of synthesis of silver colloid nanoparticles with controlled size is presented. By reduction of [Ag(NH 3 ) 2 ] + complex in sodium dodecylsulfate (SDS) micellar solution with three various reducing agents (hydrazine, formalin and ascorbic acid) the nanoparticles were produced with size below 20 nm. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), scanning electron microscopy (SEM), and UV/Visible absorption spectrophotometry. The influence of the reducing agent on the size of silver particles, fraction of metallic silver and their antimicrobial properties is discussed. In particular, the reduction of silver complex by hydrazine resulted in silver nanoparticles with size below 20nm. They showed high activity against Gram-positive and Gram-negative bacteria (lab isolated strains), and clinical isolated strains including highly multiresistant strains such as Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa.

Activation of oxidized surface of anthracite waste coal by attrition
Sokolovic, J., Stanojlovic, R.D., Markovic, Z.S.
Physicochemical Problems of Mineral Processing 48(1), 2012, 5-18

In this paper the activation of oxidized surface of anthracite waste coal was investigated. Coal weathering leads to physical and chemical changes on the coal surfaces and a reduction of its hydrophobicity and floatability. The changes and the presence of oxygen functional groups in the structure and surfaces coal was confirmed by the FTIR study on the raw and waste coal. The groups have remarkable impacts on surface charge and thus flotation kinetics. The floatability of oxidized coal may be improved by the creation of fresh, unoxidized surfaces on coal by attrition at high solid concentration prior to introducing coal to the froth flotation process. This paper presents the results of the effects of attrition on the floatability of the oxidized surface of waste coal, coal pyrite and alumino-silicate minerals through electrokinetics and microflotation experiments. The results show that the attrition, in the viscous pulp with the solid content of 50%, lead to the mechanical cleaning of oxidized surface and activation of the surface of coal particles, which agrees with the change of zeta potential and increasing floatability of coal by 10%. Obviously that the mechanical scrubbing may be able to restore the natural floatability of superficially oxidized coal by removing the thin oxidation layer from the coal surface. The results show that attrition time is an important parameter from the point of view of activating the oxidized coal surface, and positive changes in zeta potential and floatability. The change of zeta potential, as a measure surface charge state of coal particles, from -15 mV to about 0 mV, after attrition for 30 minutes, confirms positive application of attrition. Zeta potential approaching 0 mV resulted in increasing floatability down to the real possibilities of the attrition process prior the coal flotation.

Improving floatability of Taixi anthracite coal of mild oxidation by grinding
Xia, W., Yang, J., Zhao, Y., Zhu, B., Wang, Y.
Physicochemical Problems of Mineral Processing 48(2), 2012, 393-401

Grinding is widely used in ore size reduction. In this investigation, grinding is proved to be advantageous in improving the floatability of anthracite coal of mild oxidation. FTIR was used to explain changes in the main functional chemical groups of anthracite coal of mild oxidation upon grinding. Improvements of the floatability of four size fractions, namely, +0.25 mm, 0.25-0.125 mm, 0.125-0.074 mm and -0.074 mm, were discussed respectively. The results show that the floatability of anthracite coal of mild oxidation can be improved by 30 minutes grinding. The anthracite coal of mild oxidation can obtain many fresh hydrophobic surfaces by scuffing. Besides, the anthracite coal of mild oxidation can be crushed and/or ground to form fines which also contain many fresh hydrophobic surfaces. Combustible matter recovery of anthracite coal of mild oxidation, ground by 30 minutes, can reach 72.14% with ash content of 8.63%, while combustible matter recovery of original coal is 56.65% with ash content of 9.90%.

Growing role of solvent extraction in copper ores processing
Rotuska, K., Chmielewski, T.
Physicochemical Problems of Mineral Processing 42, 2008, 29-36

Heap leaching of oxide ores and cathode copper recovery by solvent extraction (SX) and electrowinning (EW) has been well established as a primary low-cost hydrometallurgical copper recovery method. Subsequently, hydrometallurgy was also gradually developed and applied for sulphidic ores and concentrates. Presently, more than 20 % of total world production of copper is achieved through the solvent extraction route. The success of this method led to a significant revival in the development of hydrometallurgical processes to recover copper from ores both sulphidic and oxidized. This work reviews the major problems related to solvent extraction from pregnant leach solutions (PLS) after leaching oxide and sulphide copper minerals.

Statistical analysis of the relationship between particle size and particle density of raw coal
Niedoba, T.
Physicochemical Problems of Mineral Processing 49(1), 2013, 175-188

The paper presents a multidimensional analysis of mineral processing feeds consisting of different amounts of different size and density fractions. The considered feed was coal which was screened into size fractions which were subsequently separated into density fractions and their weights determined. The feed material was characterized with commonly used size and density frequency and cumulative distribution plots and next approximated with the Weibull (size) and logistic (density) mathematical functions. Having the contribution of each particle size and density fraction in the feed a two-dimensional analysis of the feed size/density properties was performed using two methods. The first one is based on the best chosen cumulative frequency function for two random variables and the second uses the so-called Morgenstern family functions. In the paper the undependability of the particles size and density was investigated using statistical approach based on the so-called e test, and the correlation between these parameters using the so-called F-Snedecor statistical test. In both cases it was found that particles size and density of the investigated coal particles were dependent what means that with growth of particle size its density grew too and there was correlation between them regardless of significance level assumed for the analysis.

Non-aqueous fracturing technologies for shale gas recovery
Rogala, A., Krzysiek, J., Bernaciak, M., Hupka, J.
Physicochemical Problems of Mineral Processing 49(1), 2013, 313-321

Fracturing technologies for shale gas production were developed mainly in the USA and are currently being adapted to geological conditions and environmental requirements in other countries. This paper presents literature on theoretical and practical aspects of gas production from shale with the emphasis placed on alternatives to hydraulic fracturing. Technical and environmental aspects of non-aqueous fracturing technologies are also considered.

Effect of chemical additives on flow characteristics of coal slurries
Mosa, E.S., Saleh, A.-H.M., Taha, T.A., El-Molla, A.M.
Physicochemical Problems of Mineral Processing 42, 2008, 107-118

In the present paper, the effect of chemical additives or reagents on rheological characteristics of coalwater slurry (CWS) was investigated. The power-law model was applied to determine the non-Newtonian properties of coal slurries. Three types of dispersants namely, sulphonic acid, sodium tripolyphosphate and sodium carbonate were studied and tested at different concentrations ranging from 0.5 to 1.5% by weight from total solids. Sodium salt of carboxymethyl cellulose (Na-CMC) and xanthan gum were tested as stabilizers at concentrations in the range of 0.05 to 0.25 % by weight from total solids. It was found that apparent viscosity and flow properties of CWS are sensitive to the use of chemical additives (dispersants and stabilizers). Among studied dispersing agents, sulphonic acid recorded the best performance in modification and reducing CWS viscosity. The best dosage of all tested dispersants was found to be as 0.75 % by wt of solids. With regard to studied stabilizers, Na-CMC recorded better performance than xanthan gum. The best dosage of investigated stabilizers was found to be as 0.1% by wt. from total solids.
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