A. Ozkan

Coagulation and flocculation characteristics of celestite with different inorganic salts and polymers

Abstract Coagulation and flocculation characteristics of celestite were investigated using CaCl 2 , MgCl 2 and AlCl 3 and anionic (A-150), cationic (C-573) and non-ionic (N-100) flocculants, respectively. Isoelectric point of celestite sample studied was found to be located at a pH of 2.6 using hindered settling technique. It was determined that the magnesium ion was more effective on the celestite suspension than calcium and aluminum ions and its effect significantly varied depending on concentration and pH of the suspension. The coagulation power values for magnesium ion increased rapidly towards the 5×10 −5 M concentration and reached a maximum value (∼90%) at a pH of 11. While calcium and magnesium ions were not effective below neutral pH, aluminum ion caused the stabilization of the celestite suspension below pH 8.5. A-150 and N-100 polymers strongly flocculated the celestite suspension than C-573 polymer. While the celestite suspension with A-150 polymer was flocculated well at neutral and alkaline pH range, N-100 polymer was not much affected by the pH changes of the suspension. For the flocculation experiments with A-150 polymer at pH 11 with pre-addition of particular concentrations of calcium and magnesium ions into the suspension, i.e. destabilization process prior to the flocculation, the flocculation of the celestite suspension was enhanced by the coagulation process.

Kinetics of fine wet grinding in a laboratory ball mill

Abstract The kinetics of batch wet grinding of quartz from a feed of 600×425 μm to a product of 80% less than 8 μm have been determined using sieving and laser diffractometer sizing for size analysis. A dispersing agent was added while proceeding to longer grinding times to prevent particle agglomeration in the mill. The specific rates of breakage (Si) values obtained were higher than those of dry grinding of quartz at the same experimental conditions, but the primary breakage distribution (Bi,j) values were the same. Non-first order grinding was observed with continued decrease of the specific rates of breakage for finer grinding. The simulations of the product size distributions were in good agreement with the experimental data, providing the decrease in rates was included.

Comparison of stages in oil agglomeration process of quartz with sodium oleate in the presence of Ca(II) and Mg(II) ions

The oil agglomeration of quartz with sodium oleate in the presence of calcium and magnesium ions comprises three consecutive stages: adsorption of cations onto quartz surfaces, which leads to coagulation of the suspension, shear flocculation with sodium oleate and finally, agglomeration of flocs by kerosene. The effects of pH and cation concentration on these stages were investigated and the results were presented comparatively. It was found that all the stages of oil agglomeration of quartz exhibited sharp dependences on pH and cation concentration. That is, these stages generally took place in the pH and concentration ranges in which hydroxy complexes of the cations existed in the suspension. In the case of magnesium ion, the coagulation, shear flocculation and especially oil agglomeration of quartz improved after precipitation of hydroxide. These species of calcium and magnesium ions formed at high pH were adsorbed on the negatively charged surface of quartz, as a result of which the adsorption of sodium oleate became possible and thus the shear flocculation of the particles was achieved. Thereafter, the hydrophobic quartz flocs could be agglomerated by kerosene as bridging liquid. The increase in the shear flocculation efficiency depending on the increase of surface hydrophobicity enhanced the oil agglomeration of quartz with kerosene. The maximum recoveries for all the stages of the quartz were obtained in the presence of 10(-3) M magnesium and 5x10(-3) M calcium ions at pH 11. However, some differences in the behavior of shear flocculation and oil agglomeration of quartz suspension were observed above 10(-3) M concentration of magnesium ion.

Coagulation and flocculation characteristics of talc by different flocculants in the presence of cations

Abstract The coagulation and flocculation characteristics of talc, using anionic, cationic and non-ionic flocculants in distilled and fresh water containing Ca 2+ , Mg 2+ , Na + and K + ions were investigated. It was shown that the stability of the talc suspension remained almost constant in distilled water at all pH values, while it was strongly coagulated with these cations at pH values greater than 10.5. In fresh water, anionic and non-ionic flocculants were very effective on the talc suspensions at pH 7.2 and at pH values greater than 10.5. Flocculation of the talc suspension was assisted by the coagulation effect at pH levels greater than 10.5. The cationic flocculant was ineffective on the talc suspensions in the presence of cations at almost all pH levels. However, the cationic flocculant caused weak aggregation of the suspension with distilled water in acidic conditions.

Correlation of Flocculation and Agglomeration of Dolomite with its Wettability

Wettability is an important parameter which affects the shear flocculation and oil agglomeration behaviors of minerals. The critical surface tension of wetting (γc) as a wettability parameter describes wetting characteristics of any mineral. In this study, the correlation of shear flocculation and oil agglomeration processes of dolomite with its wettability parameter is investigated. The experimental studies have indicated that these processes improved with decreasing wettability depending on the increase of oleate adsorption despite a simultaneous increase in the zeta potential of dolomite. On the other hand, the flocculation and agglomeration of dolomite decreased with decreasing surface tension and did not occur below a particular value of surface tension, corresponding to the critical surface tension of wetting (γc) and the critical solution surface tension (γc-a) values, respectively. Also, the γc-a values are slightly higher than the γc values, indicating that the agglomeration of the particles requires a lower wettability.

A new microcolumn flotation cell for determining the wettability and floatability of minerals.

Flotation is one of the most important physicochemical processes for mineral separations and other recovery operations. Flotation machines have been developed since the beginning of the 19th century and are still under intensive research and development. The cell we devised is a combination of the Canadian column flotation cell and the Partridge-Smith cell. The materials used for the construction of the new cell are cheap and use available laboratory accessories and aquarium materials. The cell functions well in terms of its scale, control, and sample requirement. It can be used both in the laboratory for research and in classrooms for demonstrations of experiments. Some of the data obtained by the flotation method using this cell are in good agreement with data measured independently on the same minerals by the contact angles method. The critical values of surface tension of wetting (gamma(c)) for talc, sulfur, and chemically treated surfaces of calcite and barite obtained by the contact angle measurements were 31, 26, 30.5, and 31.2 mN/m, respectively. On the other hand, the gamma(c) values of those minerals, obtained using our new designed flotation cell, were 30, 28, 31.4, and 34.5 mN/m, respectively. The measurements obtained in our experiment are also comparable to those previously published for the same minerals.

Prediction of the wettability characteristics of some minerals from their breakage parameters

Abstract In this contribution, the breakage and wettability properties of calcite and barite minerals were presented and some correlations were established between these experimentally determined parameters. The γ c relates to S i by a relationship: γ c =−4.94 S i +32.5 (calcite) and γ c =−5.70 S i +36.1 (barite), where γ c is the critical surface tension of wetting of mineral determined by flotation technique and S i is the specific rate of breakage of mineral obtained from grinding tests. Another relationship found is expressed by: m f =4.20 S i +5.30 (calcite) and m f =7.96 S i +6.71 (barite), where m f in to slope of the flotation recovery curve. These relationships will help us to predict the wettability behavior of solids in surface chemistry related processes, by knowing the breakage parameter S i previously from any grinding tests.

Hydrophobic flocculation of talc with kerosene and effects of anionic surfactants

ABSTRACT The variation of the hydrophobic flocculation behavior of talc mineral with pH, kerosene concentration, stirring speed, flocculation, and settling times was investigated. The experimental studies showed that the flocculation of talc suspension increased to a particular point with increasing kerosene concentration and thereafter decreased slightly. Also, the flocculation with kerosene was not much affected by the pH changes of the suspension. On the other hand, sodium oleate, sodium dodecyl sulfate (SDS), and Aero 801 used as anionic surfactant in conjunction with kerosene provided significant increases in the flocculation of talc, and depends on increasing surface hydrophobicity of the particles. Especially, in the presence of sodium oleate along with kerosene, the talc suspension could be flocculated with a recovery of 95%. Consequently, the enhancement with nonpolar oil was more significant for the hydrophobic flocculation of talc suspension promoted by long hydrocarbon chain surfactant (sodium oleate) than short hydrocarbon chain surfactants (SDS and Aero 801).

Flocculation of coal suspension with mono/dual polymer systems and contribution of Ca(II)/Mg(II) ions

Abstract In the experimental study carried out on mono-flocculation, anionic and especially non-ionic polymers strongly flocculated the coal suspension than cationic polymer. The dual-flocculation of the coal suspension with cationic and anionic polymer combination was also studied and the high performances of flocculation were also reached with dual-polymer approach. Furthermore, dual-polymer system required lower concentrations for the successful flocculation of coal particles. On the other hand, the pre-destabilization of the coal suspension with calcium and magnesium ions at particular pH and concentrations highly improved the flocculation of fine coal particles with these polymers.

Correlation of the breakage parameters with the critical surface tension for wetting of barite

Abstract In this paper, we present a correlation and experimental data for a relationship between the breakage and the wettability for barite mineral. The breakage parameters, which are readily obtained from grinding test, are the specific rates of breakage ( S i ) and the fineness value ( γ ) of the primary breakage distribution function ( B i , j ). The wettability parameter, which is easily obtained from contact angle measurements or flotation tests, is the critical surface tension for wetting of any mineral ( γ c ). The barite sample studied for the correlations was ground in a laboratory-size porcelain ball mill and tested extensively for wettability using a contact angle goniometer and our newly designed micro-column flotation cell. There is a significant relationship between the S i and γ c values from our experimental work on the barite sample, where the higher S i means lower γ c , i.e., a mineral was more hydrophobic when it had a higher S i value, or a more rapid breakage of the top sizes leads to better hydrophobicity or floatability. Another relationship was found between the fineness value ( γ ) of the breakage and the critical surface tension for wetting ( γ c ), which indicates that as the γ value increases (meaning less fines produced), the γ c increases (meaning less hydrophobicity) based on the contact angle and flotation tests.