In this study some characterization tests of acidic pumice were performed using various techniques such as Mercury Intrusion Porosimetry (MIP), Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Thermal Analysis (DTA-TG), FTIR and its electrokinetic properties in water such as zeta potential (ZP), isoelectrical point (IEP), indifferent, specifically adsorbing and potential determining ions were determined. The results showed that (i) pore dimensions of the irregular or oval and fibrous cavities of the pumice varied between 0.05 μm and 2 mm depending on its particle size and these cavities usually did not intersect each other; (ii) as the pumice particle size decreases, both total pore volume and total pore surface area significantly decrease as well; (iii) pumice maintained its thermal stability approximately up to 900°C; (iv) pumice had a negative surface charge between pH 1.8 and 11.4; and (v) Cl − , Br − SO 4 2− , Na + , Al(OH) 2 + and Ca 2+ ions were indifferent, C 16 H 33 (CH 3) 3 N + , Al 3+ and Al(OH) 2+ cations were specifically adsorbing and, H + and OH − ions were potential determining ions for acidic pumice.

The effectiveness of coagulation (at pH values of 6, 7.5, and 9), flocculation (at pH 9), and coagulation plus flocculation (at pH 9) on turbidity removal from natural stone (travertine) processing wastewaters (NSPW) were examined by applying classical sedimentation tests. FeCl 3 N 6 H 2 O, AlCl 3 , and Al 2 (SO 4 ) 3 N 16 H 2 O were used as coagulants and a polyacrylamide based anionic polymer was used as the flocculant. In this way, it was found that the coagulation method alone was not sufficient to purify NSPW, whereas flocculation and coagulation plus flocculation methods provided superior purification. Among the coagulants used, AlCl 3 gave the best result in terms of turbidity removal by coagulation from NSPW at pH 6 and 9, whereas the turbidity removal performances of the three coagulants were almost identical at pH 7.5. In addition, relatively low pH (i. e., pH 6) improved the purification performance of all coagulants. During coagulation of NSPW at pH 6, a charge neutralization mechanism played a decisive role in turbidity removal. However, in neutral (pH 7.5) and slightly basic (pH 9) media, a sweep coagulation mechanism was predominant. For flocculation of NSPW, the basic mechanism comprised of polymer bridging.

Detailed characterisation of natural sepiolite from the Eskisehir region of Turkey was performed using X‐ray diffraction, X‐ray fluorescence, field emission scanning electron microscopy, specific surface area (BET method), Fourier transform infrared spectra, derivative thermogravimetry (DTG) and differential thermal analysis. Electrokinetic properties of natural‐ and acid‐activated sepiolites were investigated as a function of the concentration of various electrolytes, such as NaCl, KCl, LiCl, CaCl2, MgCl2, NaNO3, Na2CO3, FeCl3 and Al(NO3)3. While mono and divalent cations and anions did not change the surface charge of natural‐ and acid‐activated sepiolite, trivalent cations changed the surface charge from negative to positive. Acid‐activated sepiolite samples shifted towards the positive region in nearly all electrolyte solutions when compared with the natural sepiolite. © 2011 Canadian Society for Chemical Engineering

The adsorption of a cationic dye, Basic Blue 16 (BB16), by montmorillonitic clay was studied in detail. Changes in the molecular structure during adsorption were analyzed by FTIR spectroscopy. BB16 adsorption onto the clay mainly results from hydrogen bonding between OH and NH 2 groups of dye molecules and OH groups of clay and electrostatic interaction between the negatively charged clay surface and cationic dye. The montmorillonitic clay dose had an inverse effect on the adsorption performance, while the highest dye removal was 305 mg/g at pH 3.6. An increase in temperature and dye concentration positively enhanced the adsorption capacity of the montmorillonitic clay. Temperature had no effect on the adsorption at a dye concentration less than 500 mg/L, while dye adsorption was positively enhanced at elevated dye concentrations. Three-parameter equations provided higher better fitting than two-parameter equations while the Freundlich model had the highest correlation coefficient and the lowest error values with experimental data. The BB16 adsorption was well followed by pseudo-second order model and the rate of adsorption process was controlled by surface and intraparticle diffusion. Thermodynamic evaluations revealed that the adsorption process was spontaneous and endothermic, while the randomness increased during adsorption. Experimental results indicate that montmorillonitic clay from Eskisehir is a promising adsorbent for the removal of cationic dye molecules from aqueous solutions.

The Ball Mill Abrasion (BMA) test was developed by the University of Queensland Materials Performance group to simulate the high stress abrasion conditions experienced in production ball mills. It gives accurate predictions of the service life of wear resistant alloys in mill liner and grinding media applications. In this paper the BMA test methodology was applied to investigate the wear rates of four grades of grinding media using two small laboratory ball mills. The rankings obtained from the tests were identical with those from the full BMA test, although the difference between the different grades was not as marked. It is concluded that untrained personnel can use a simple small-scale procedure to evaluate relative but not absolute grinding media wear rates.

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