Ugur Ulusoy

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.

Zinc Recovery From Lead–Zinc–Copper Complex Ores by Using Column Flotation

Pb–Zn–Cu complex ore from Balıkesir–İvrindi district have been concentrated by GESOM A.Ş. using a selective mechanical flotation technique. Ore feeds containing 3.23% Pb, 0.52% Cu, and 2.71% Zn were concentrated by six stages of cleaning and four stages of scavenging. The final zinc concentrate which contains 2.13% Pb, 1.14% Cu, and 52.77% Zn were produced with 61.38% Zn recovery. In this study, the effects of air rate, bubble diameter, gas holdup, and superficial air rate on the column flotation performance were investigated. In order to obtain best results, operation parameters were optimized. Besides, the number of cleaning and scavenging stages of zinc circuit was reduced by using column flotation instead of mechanical flotation. Hence, higher grade zinc concentrates with higher recovery were obtained. Using three stages of cleaning and three stages of scavenging, the zinc concentrate having 58.81% Zn was produced with a recovery of 74.21% indicating an improvement in final zinc concentrate. This achievement of column flotation method was recommended as an alternative method for the zinc circuit to the plant mentioned above, since it will reduce the operating costs.

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.

Characterisation of surface roughness and wettability of salt-type minerals: calcite and barite

Abstract Salt-type minerals of calcium (calcite) and barium (barite) are important raw materials for metallurgical, chemical and agricultural industries. Flotation is the primary process for recovering these minerals from ores. This study reports the determination of the surface roughness and wettability characteristics of these salt-type minerals ground in ball, rod and autogenous mills. Surface roughness values of these minerals have been expressed by the calculated surface roughness (RBET) factors based on BET (Brunauer-Emmett-Teller) surface area measurements. The wettability characteristics (γC) of these minerals ground by three different mills were also determined by a microflotation technique using the EMDEE MicroFlot agitator. Finally, significant correlations were found between the surface roughness (RBET) and wettability (γC) characteristics. The results revealed that the γCvalues increase with increasing RBET values. This means that if a mineral has lower surface roughness value, it will float better with lower γC value that indicates more hydrophobic character. The empirical relationships could be stated as γC = a × RBET + b type of equations; where a and b are constants.

Breakage parameters of chromite and simulation of the product-size distributions

Abstract The breakage parameters of a run of mine chromite for dry and wet ball milling were obtained by means of standard S and B test methods. This method requires a small amount of power for grinding for different length of time in a laboratory ball mill to obtain the breakage parameters. The single sized fraction of a − 425 + 250 μm feed of material obtained from our laboratories was ground for different lengths of time in a laboratory ball mill. The specific rate of breakage, (S i ), for dry milling was determined to be 0.28 min −1 , while the S i value for wet grinding was 0.56 min −1 . The cumulative breakage-distribution function (B ij ) values (ϑ, γ and β) obtained were the same for dry and wet ball milling. The , γ and β values were 0.75, 1.14 and 7.9, respectively. The simulation of the product-size distributions using a “Two-Stage Ball-Mill Circuit Simulator: PSUSIM” was performed by making use of the obtained S and B parameters. The simulated results were in good agreement with the experimental results.

Dynamic image analysis of differently milled talc particles and comparison by various methods

ABSTRACT In this study, particle shapes of talc mineral ground by various types of mills were determined using automated dynamic image analyzer by counting averagely 19,000 particles for each mill product. The results were expressed in terms of circularity (C) and bounding rectangle aspect ratio (BRAR). It was concluded that particles created by rod mill had the highest BRAR and the lowest C, while the particles having the highest C and the lowest BRAR were obtained by autogenous milling. The statistical significance of mean shape values of different milled particles was also tested by using one way analysis of variance (ANOVA) and post hoc Tukey test. The ANOVA results showed that there are significant differences among C and BRAR mean values of particles produced by autogenous, ball, and rod mill at 99% level of confidence. The results were in good agreement with the results obtained by other techniques employed previously. Thus, the result of dynamic image analysis (DIA) can be used for quality control of the products of talc mineral as the morphology decides whether specific talc is appropriate for a specific application or not.

Zinc Recovery from a Lead–Zinc–Copper Ore by Ultrasonically Assisted Column Flotation

In this study, zinc recovery from lead–zinc–copper ore was performed by column flotation with and without ultrasonic pretreatment. First, optimization of operational parameters was carried out by only single-stage column flotation without ultrasonic pretreatment. A zinc concentrate containing 16.93% Zn was obtained from the feed containing 2.71% Zn with 29.41% recovery using single-stage column flotation. Second, a concentrate containing 24.51% Zn was obtained with a recovery of 39.97% when ultrasonic pretreatment was applied to zinc beneficiation by single-stage column flotation at these optimized conditions. Third, a zinc concentrate having 53.41% Zn was produced with a recovery of 71.48% by using three stages of cleaning and three stages of scavenging flotation by column. Finally, a zinc concentrate containing 73.32% Zn was received with a recovery of 76.44% when the ultrasonic pretreatment was used before column flotation by multiple stages. The results revealed that zinc grade and recovery were increased by ultrasonically assisted column flotation tests. It may be due to the increasing dispersion of ultrasound, increasing adsorption of collectors, and the hydrodynamic cavitation which produced small bubbles attaching to the hydrophobic particles, thereby increasing contact angle and attachment.

Machine Vision Based Particle Size Distribution of Particulate Minerals and its Experimental Verification

Reliable and accurate measurement of particle size and subsequent analysis of particle size distribution (PSD) is central to characterization of particulate minerals. Traditionally PSD of particulate materials was determined using standard mechanical sieving, but it was shown to be deficient in accurate particle size measurements, hence PSD analysis. In this paper a highly inexpensive machine vision based approach was proposed as an alternative to mechanical sieving. The test mineral used was ball-milled celestite. This machine vision approach used a document scanner as imaging device and a user-coded java ImageJ plugin performed the image processing and automated the PSD analysis. The acquired color images were preprocessed to binary images and the particles analyzed after grouping them based on their distinct length. Volumes of all particles were evaluated assuming a prolate spheroid geometry from measured lengths and widths. A new approach of using sum of volumes as weighting factor (Svolume) was utilized for particle grouping in ASABE Standard PSD analysis. The plugin also evaluated several significant dimensional (16) and distributional (27) parameters that characterize the PSD of samples. Standard mechanical sieving of samples was performed for experimental verification and results compared with machine vision method. The cumulative undersize PSD followed a log-normal distribution, and the plot against particle size exhibited a linear trend. Shapes of log-normal plot of cumulative undersize PSD were similar between both methods; however, the mechanical sieving curves lagged by 0.2-0.5 mm. The deviation was attributed to the “falling-through” effect of longer particles through sieve openings.