M. Yekeler

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.

Kinetics of dry grinding of industrial minerals: calcite and barite

Abstract This paper presents the kinetics study of dry ball milling of calcite and barite minerals. The experimental mill used was a laboratory size of 209 mm diameter, 175 mm length, providing a total mill volume of 6001 cm3, with a total mass of 5.6 kg of steel balls of 46, 26 and 12.8 mm diameter, so as to occupy 20% of the mill volume and with a speed of rotation of 74 rpm. The breakage parameters were determined by using the single sized feed fractions of −850+600, −600+425, −425+300 and −300+212 μm for calcite and −850+600, −600+425, −425+300 μm for barite mineral. The Si (specific rates of breakage) and Bij (primary breakage distribution) values were obtained for those feed size fractions in order to predict the product size distribution by simulation for comparison to the experimental data. As the feed size fractions become coarser, the Si values increase. The highest Si value obtained for calcite was 0.86 min−1 for the −850+600 μm feed fraction, while it was 0.42 min−1 for the −300+212 μm feed when 26-mm ball sizes were used in the mill. The ball size effect was also investigated against the Si values in where the Si value increases when the ball sizes become smaller. The Bij values remained essentially the same for each feeds; the average of φ, γ and β values for all feed sizes of calcite were 0.65, 0.95 and 4.40, respectively. On the other hand, the highest Si value obtained for barite was 0.99 min−1 for the −850+600 μm feed fraction, while it was 0.66 min−1 for the feed size fraction of −425+300 μm when 26-mm ball sizes were used in the grinding mill. The Bij values also remained unchanged for each feeds; φ, γ and β values of barite for the average of all sizes were obtained to be 0.69, 0.81 and 3.94, respectively. The simulations of the product size distributions of both calcite and barite minerals were in good agreement with the experimental data using a standard ball mill simulation program. The slowing down effect was seen in the mill after 4 min of grinding for calcite and after 2 min of grinding for barite.

Chapter 9 Breakage and Morphological Parameters Determined by Laboratory Tests

Publisher Summary This chapter highlights the breakage and morphological parameters determined by laboratory tests. Size reduction of solids and minerals by crushers and grinding mills is an important industrial operation involving many aspects of mineral, metallurgical, power and chemical industries. Size reduction by crushers does not create problems because of high energy consumption and capital cost per ton per hour; however, fine grinding by mills consumes a lot of energy and causes high abrasive wear. As mineral particles are reduced to finer product sizes, their surfaces become more important. Surface characteristics and properties affect any of the fine particle processing operations. The particle morphology plays a very important role in many aspects of powder technology and enables one to predict how the minerals may behave when they are ground and to determine how those minerals may respond to processing. Obtaining the breakage and morphological parameters by laboratory studies helps to better understand the breakage behavior and predict the process outputs in desired unit operations to solve complex problems.

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.

Effect of the hydrophobic fraction and particle size in the collectorless column flotation kinetics

Abstract In order to investigate the particle size effect of a highly hydrophobic mineral (talc), different size fractions were floated in a column flotation cell to obtain the effect of flotation-rate constants (k) on the kinetics of flotation. Pure talc (100% talc or hydrophobic fraction) gave the highest recovery (97.5%) for particles below 38 μm. As the particle size fractions became coarser, the maximum recoveries as well as the flotation rate constants (k) decreased. The talc mineral containing different fractions of calcite (which is a highly hydrophilic mineral) when no chemicals were used gave the highest recovery (57.4%) when the fraction of talc was highest (75% talc+25% calcite). The lowest recovery obtained was 5.6%, when 100% calcite was present. The flotation rate constants decreased as hydrophilic fractions were increased. This paper presents the data and describes the approach used in the kinetics of column-flotation experiments.

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.

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.

Correlation of the Particle Size Distribution Parameters with Sieving Rate Constant

Controlling the particle size distribution (PSD) of raw materials, intermediates, and end products is very critical to the success of the powder technology related processes. This study presents the evaluation of the sieving characteristics of some industrial minerals, namely, quartz, talc, and barite, and the establishment of possible correlations between the PSD and kinetics parameters. PSD of the −600 µm fractions of quartz, talc, and barite minerals were plotted in Schuhmann mathematical approach. The size modulus (ks) and distribution modulus (αs) were obtained for each mineral. Then, sieving kinetics study was carried out for each mineral to determine optimum sieving time and sieving rate constant (kk). Further, the size distribution parameters were correlated with the sieving rate constant values for those minerals. While distribution modulus (αs) increases, size modulus (ks), and average sieving rate constant values (kk) decrease. The correlations were found to be ks = −293.52αs + 730.87 and kk = −0.0041αs + 0.0454. The results showed that near-mesh particles play important role in the overall kinetic process.

Combination of Different Size Distributions for Mineral Particles by Applying Experimentally Determined Apparent Mean Shape Factor

As is well known, the behavior of systems of fine particles is strongly dependent on the size of the individual particles, and the size effects become increasingly important as the particles become progressively smaller. This study covers two different size analysis techniques, sieving and laser diffraction measurement, and constructs whole size distribution for different mill (ball and rod) products of some industrial minerals: barite and quartz minerals. A smooth overlap of corrected laser diffraction size distribution and sieve size distribution was obtained by applying the particle size with the apparent mean shape factor shifting to the right side of the curve for the rod-milled barite and ball- and rod-milled quartz. The apparent mean shape factors determined from the corrected particle size distributions were found to be 1.02 and 1.39 for ball- and rod-milled barite and 1.29 and 1.25 for ball- and rod-milled quartz, respectively. The results indicate that the ball-milled products of barite mineral have more regular (rounder in shape) particles than those of rod-milled barite, but there are not significant differences between the shape factors of ball- and rod-milled products of quartz mineral, i.e., both of them have irregular particles that deviate from spherical shape, as evident from the SEM pictures taken.