Mill Size Research Articles

Preparation of Cobalt Blue Ceramic Glaze Ink Based on Sol- Gel Method

Cobalt blue pigment precursor xerogel was prepared by sol-gel method and then calcined to obtain cobalt blue pigment by self-propagating combustion. The effect of process parameters such as pH value, metal ion concentration, dispersant, sol reaction temperature, citric acid dosage and calcination temperature on the crystalline form of cobalt blue pigment was studied. The ultrafine cobalt blue pigment obtained by the above method is used as the inorganic pigment of the blue ink, and the blue ceramic ink is prepared by a dispersion method. The effects of the milling medium size, milling time, dispersion effect of different kinds of dispersants, and solvent addition was studied. Dry gel is processed by self-propagating combustion and then calcined athigh temperature. With the calcination temperature increasing, pigment color is more bright. At 1250 ?, thegrain size of the sample is approximately 200 to 500 nm. The sample is tested by a colorimeter, and its b*value is -43.09.

Historical assessment of metal recovery potential from old mine tailings: A study case for porphyry copper tailings, Chile

The metal mining activity has been the source of large volumes of tailings that must be stored in tailings storage facilities (TSFs). Since tailings might contain residual valuable metals, these are often subject of assessment studies aimed to find a feasible way to reprocessing. One of these TSFs was built and operated during the 1930’s for the exploitation of a giant porphyry copper deposit in Chile, a deposit that is still under exploitation today. For these old tailings a historical assessment was varied out about the copper recovery potential in a reprocessing scenario by flotation. Based on theoretical concepts and available historical operational data, it can be shown that the main reason for the relatively high copper grades found in these tailings are the corresponding high grades of the processed ores, instead of being the result of an inefficient past technology of flotation with consequential low recoveries. Conversely, the former flotation circuit was optimal concerning the recovery of copper sulphides favoured by the less restrictive high copper content of these sulphides. Consistently, it is argued for the study case that the main advances in flotation circuits have focused on improving selectivity without sacrificing recovery, due to the changes in the mineralogy of the exploited ores. These are relevant facts for a reprocessing scenario, indicating a low copper recovery potential if the current conventional flotation technology is considered; thus other and/or newer processing technologies could be more efficient for recovery of the remaining copper. There are hydrometallurgical potential alternatives for reprocessing but limitations are expected in relation to milling size of the tailings material. The present findings may apply elsewhere, due to the high representativeness of the present study case.

Surface engineered excipients: II. Simultaneous milling and dry coating for preparation of fine-grade microcrystalline cellulose with enhanced properties

A solventless process for simultaneously milling and dry coating microcrystalline cellulose (MCC) was investigated for producing fine excipients in five different sizes (∼20, 25, 30, 35, 40 µm) having high bulk density (BD), good flow function coefficient (FFC), and excellent compaction. Avicel PH-102, used as the starting material, was milled and coated with two grades of silicas, hydrophobic and hydrophilic (R972P and A200), using a fluid energy mill (FEM). Through judicious selection of the FEM feed rate, feeding pressure, and grinding pressure, five desired milled sizes were produced. The bulk density of all the milled-coated (1 wt% A200) excipients was significantly better than uncoated-milled MCC, Avicel PH-102, and Prosolv 50 and 90. Whereas the FFC values were greater than uncoated-milled MCC, Avicel PH-102, and Prosolv 50 (latter for ∼30, 35, and 40 µm sizes). The tablet compaction testing was used to evaluate compactibility (tensile strength vs tablet porosity), compressibility (tablet porosity vs compaction pressure), and tabletibility (tensile strength vs compaction pressure). The results indicate that all finer grade milled and A200 coated MCC had lower porosity and higher tablet strengths than Prosolv 50 and 90 at all compaction pressures. Surprisingly, the BD and FFC were better for A200 than for R972P coated-milled MCCs; explained through analyzing inter-particle contact models. Finally, milling did not increase the moisture content but coating with silica led to a slight increase; A200 higher than R972P. It is hoped that these engineered excipients would help formulators with a multitude of options for finer excipients without loss of flow and bulk density.

Step annealing and fading studies on EPR signals of Durango apatite for various grain size fractions at the edge of the nano-scale; comparison with the corresponding luminescence results

Durango apatite is a material that exhibits very strong athermal fading (AF) of luminescence signal. In this study, the EPR signals of natural Durango apatite in various different grain dimensions (ball milled for various durations up to 48 h and microscale grain size) were studied. The obtained EPR signal at room temperature yielded three different components with g values 2.0534 (hole center), 2.0398 (hole center) and 1.9920 (electron center). These components were observed for the reference grain size fraction of 100–180 μm; however, prolonged ball milling erases the two hole centers. The behaviour of all obtained components was investigated by step annealing processes (a) between room temperature and 400 °C in steps of 25 °C for 5 min and (b) between 400 °C and 1100 °C, in steps of 100 °C for 1 h. The EPR component with g value 1.9918 was almost totally removed until 1100 °C, while those with g values 2.0534, 2.0398 were erased after annealing at 500 °C and 400 °C respectively. The fading of EPR components was investigated for each ball milling (BM) and microscale grain size independently, at different storage times between 0 and 1000 min. Based on the results of fading and step annealing studies, the EPR component with g value 2.0398 could be directly correlated to the main dosimetric TL trap, while the component with g value 1.9920 appears to be responsible for TA – OSL signal for microscale grain size apatite, corresponding thus to a very deep trap. The behaviour of remnant EPR signal versus storage time could be successfully described by equations based on quantum mechanical tunnelling mechanism.

STUDY OF THE EFFECTS OF GYMPSUM, POZZOLANIC ADDITIVE MIXTURES AND THEIR FINENESS ON THE STRENGTH OF PCB50 FICO CEMENT

In the study, raw materials including clinker, gypsum, pozzolan were separately milled on a ball mill (the ball mill size: φ500 mm × L500 mm, productivity: 5 kg / grinding time) to achieve the desired blaine fineness. A mixture is mixed at the calculated ratio includes of 90 % fineness clinker, 5 % fineness gypsum and 5 % fineness pozzolan (In it, pozzolanic additive is mixed at different fineness levels). The effects of the mixture of gypsum and fineness pozzolanic additive as well as the fineness of pozzolanic additive to strength of PCB50 Fico cement were investigated. The study shows that, pozzolanic additive have reduced the strength of cement. But, when pozzolanic additive is mixed with gypsum, this additive mixture has increased the strength of the cement at the late time (at the age of 28 days). The fineness of pozzolan has little effected on the early strength of cement.

Dynamic modeling and simulation of a SAG mill for mill charge characterization

The modeling and simulation of semiautogenous (SAG) mills have been widely used in the design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. This paper attempts to characterize mill contents by solving Whiten’s first-order content-based model in the MATLAB/Simulink environment. The parameters in the model, such as breakage rate constant, discharge rate and appearance function, were estimated using process and design data collected from a gold mine operating in Alaska coupled with a nonlinear parameter estimation scheme. This model was then used to predict the dynamic responses of other key operational variables, such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated using dynamic response data from the plant to encompass operational characteristics of SAG mill behavior.

Optimization of a combined wet milling process in order to produce poly(vinyl alcohol) stabilized nanosuspension.

PurposeThe article reports a wet milling process, where the planetary ball mill was combined with pearl milling technology to reach nanosize range of meloxicam (Mel; 100–500 nm). The main purpose was to increase the dissolution rate and extent of a poorly water-soluble Mel as nonsteroidal anti-inflammatory drug as well as to study its permeability across cultured intestinal epithelial cell layers.MethodsViscosity of milled dispersion and particle size distribution and zeta potential of Mel were investigated and differential scanning calorimeter and X-ray powder diffractometer were used to analyse the structure of the suspended Mel. Finally in vitro dissolution test and in vitro cell culture studies were made.ResultsIt was found that the ratio of predispersion and pearls 1:1 (w/w) resulted in the most effective grinding system (200-fold particle size reduction in one step) with optimized process parameters, 437 rpm and 43 min. Nanosuspension (1% Mel and 0.5% poly[vinyl alcohol]) as an intermediate product showed a stable system with 2 weeks of holding time. This optimized nanosuspension enhanced the penetration of Mel across cultured intestinal epithelial cell layers without toxic effects.ConclusionThe dissolution rate of Mel from the poly(vinyl alcohol) stabilized nanosuspension justified its applicability in the design of innovative per oral dosage form (capsule) in order to ensure/give a rapid analgesia.

FEASIBILITY ANALYSIS OF USING BIOGAS RECOVERY FROM PALM OIL MILL EFFLUENT

The increasing of crude palm oil (CPO) production in Indonesia is followed by the increasing of palm oil mill effluent. Unfortunately, the open system effluent treatment carried out by most of the palm oil mills potentially generates methane gas emission and increases greenhouse gas concentration in the atmosphere. This study proposes of using methane gas recovery for alternatively flaring and generating electricity, and analyze it in the framework of Clean Development Mechanism. Samples of effluent were taken from the three size of palm oil mills (60, 40, and 30 tonnes per hour of empty fresh bunch) in north Sumatra. The results indicate that capturing methane gasfrom the palm oil mill effluent and using the biogas for generating electricity mainly and flaring the rest will reduce carbon emissions as well as generate the additional income for the palm oil mill business.keywords : POME, methane, carbon emission, generating electricity, feasibility analysis of business

Cave fragmentation in a cave-to-mill context at the New Afton mine Part II: implications to mill performance

The productivity of milling circuits is sensitive to the size of mill feed. Uncertainty about the size of caved ore presents unique challenges to forecasting and controlling mill throughput rates. Part I of this paper showed how fragmentation size and hang-up frequency relate to geology, proximity of drawpoints to the cave boundary and the height of draw at the New Afton mine. The second part, presented here, investigates the impact of varying caved fragment size on mill performance. Analysis of historical mine and mill data showed that mill feed size and subsequently mill throughput are sensitive to the areas being mucked within the cave. Fragmentation measurements of drawpoint muck, comminution tests and calibrated mill models were used to assess the impact of variations in feed size and hardness on New Afton mill performance. Image-based size analyses of drawpoint muck and comminution tests showed that coarser material generally contained harder rock.

Multiple Factor Analysis on Preparation of Cellulose Nanofiber by Ball Milling from Softwood Pulp

This work aimed to investigate the effects of various single factors and their interactions on the preparation of cellulose nanofiber (CNF) using ball milling. These factors included the milling ball size, milling time, mass ratio of milling ball to cellulose pulp, and alkali concentration, as well as their complicated interactions. The Taguchi method was applied to the experimental design to systematically study the influences of these factors on the yield of CNF. A method for evaluating the yield of CNF was developed. Both of the simple analysis (SA) and analysis of variance (ANOVA) of the experimental results indicated that the most significant factor influencing the yield of CNF was the mass ratio of milling ball to cellulose pulp. The interactions between this factor and other single factors, e.g., milling time, also showed significant influence on the yield of CNF. Although the influence of milling ball size was negligible, its interaction with mass ratio of milling ball to cellulose pulp must be considered during production. Based on these findings, a mini scaled-up practice was proposed to demonstrate the possibility of the application of ball milling on the mass production of CNF.

Simulation of Choghart AG mill circuit using JKSimMet software and investigating the possibility of converting to SAG mill

Summary The variation of feed characteristics of the Choghart Iron Processing Plant has resulted in the reduction of AG mill efficiency. In this research, the possibility of converting the Choghart AG mill to SAG mill to stabilize the mill power draw and improve the grinding process was investigated. The JKSimMet software was used to simulate the circuit and predict the effect of charging steel balls to the AG mill. The results of grinding tests on the ore samples were used to simulate the circuit. The product size distribution predicted by the software was very close to the actual product size of the AG mill. The simulation of the circuit, using different tonnage of 100 mm steel balls showed that the mill throughput could increase by around 6 percent with a slight increase in the mill product size. The actual results of adding the steel ball to the plant were in agreement with the simulation results. Introduction The throughput of Choghart AG mill circuit was lower than the expected level for grinding the oxidized (or high Fe/FeO ratio) ores. Converting the AG mill to SAG mill to increase the grinding of this type of ore was the investigated option. The circuit was simulated by JKSimMet software and then adding of steel ball to the system was evaluated. The results were validated using the plant-scale studies. Methodology and Approaches Samples from the feed and product streams were collected, the relevant grinding tests were conducted and the selection and breakage functions of the ore were determined. The ore breakage test results and the specification of the feed material and AG mill and vibrating screen were used as input data to the JKSimMet software. Then charging different tonnage of the steel balls to the AG mill was evaluated. Plant-scale experiments were also conducted. Results and Conclusions Based on the impact and abrasion tests of the feed samples this ore was considered as a medium hard type ore. The simulation result for the mill product size distribution was very close to the actual data of the plant. Therefore, this software could be used to predict other changes in the circuit. The simulation results showed that by adding 5 and 10 percent (volume) of 100 mm steel balls to the Choghart AG mill its throughput could be increased by around 3 and 7 percent, respectively. The plant scale experiments with the same type of steel ball were in agreement with the simulation results. As it was expected the mill product size increased slightly

Determination the Effective of Grain Size on Gold Recovery by Integral of Sieve Analysis and Atomic Absorption Spectroscopy Methods

The sieve analysis and atomic Absorption methods were applied for 21collected samples around Atbara region - River Nile State- Sudan. Three types of grinder were used in this study they are (1) A grinder (2) B grinder and (3) mill size to given us the general trend of gold concentrate with preferable grain size in area of case study. The gold assay result for different grain size within same sample reflect direct relationship between gold concentrate and grain size which gold increasing with finer grain size. he grain size equal or less than 0.075mm is the preferable size to recovery most gold from original material, and there is a difference in types of mills and efficiency, For each mill grinding time for each sample varies from the mill to another and it is reliable Depending on the test rate of the sieves in the sieves and definitely affects the reading of the concentrations of samples and therefore control the rate of raw inside is known and the percentage of milling as well as all depends on the quality control of the mining plants and reduces errors. From this study we conclude the sieve analysis isgood method to evaluate quality of various grinders.

Modeling of particle size distribution and energy consumption of wet milled maize at varying soaking period and method in the production of Ogi

ABSTRACTEnergy consumptions and particles size distribution of soaked maize grains at varying time were studied and modeled. Rosin–Rammler–Bennet (RRB) model well fitted first milling size distribution with a high coefficient of determination (R2) and low root mean square error (RSME). The milling energy of maize grains decreased significantly (p < 0.05) with increase in soaking time. The milling energy decrease from 32 to 8.72 kWh/kg and 32.00 to 9.00 kWh/kg for maize variety E9W at 24th hour soaking conditions of 28 and 65°C, respectively. Similar observations for A4W, B2Y and C3Y at 24 h of soaking were recorded. The Work index, Kick’s and Rittinger’s constants decreased with increase in soaking time. There was significant difference (p < 0.05) in values obtained for Bond work index, Rittinger’s and Kick’s constants; these decreased with increase in soaking time. Predicted energy consumption followed similar trend. The interaction effect between energy consumption, Moisture content, and Milling time showed a high R2 (0.8767–0.99349); while the regressed model for determining energy consumption from relationship between the mass, moisture content, milling time and the ratio of the geometric diameter mean and final size of the product were also established in this work with R2 ranging from 0.9355 to 0.967.

Effects of processing, particle size and moisturizing of sorghum-based feeds on pellet quality and broiler production.

ObjectiveThis study aimed to assess the effect of pelleted and expanded sorghum-based feeds prepared with different moisture levels and particle size of ingredients on metabolizable energy, ileal digestibility of amino acids and broiler performance.MethodsThe experiment was performed with 720 male broiler chicks of the Cobb strain, with treatments of six replications, with 15 birds each; they were arranged in a completely randomized design and 2×2×2 factorial scheme (pelleted or expanded feed processing, 0.8% or 1.6% moisture addition in the mixer, and particle size of 650 or 850 microns).ResultsHigher pellet quality (pellets, % and pellet durability index [PDI]) was obtained in expanded diets and inclusion of 1.6% moisture. The particle size of 850 microns increased the PDI of final diet. All studied treatments had no significant effect on weight gain and broiler carcass and cut yields. Lower feed conversion occurred for birds fed pelleted feed at 42 d. The highest apparent metabolizable energy (AME) and apparent metabolizable energy corrected to zero nitrogen balance (AMEn) values of feed in the initial rearing phase (10 to 13 days) were observed in birds fed pelleted feed or for feed prepared with 1.6% moisture. The highest ileal digestibility coefficients of amino acids were obtained with the consumption of pelleted feed prepared with a particle size of 650 microns and 1.6% moisture.ConclusionPelleted feed prepared with a milling particle size of 650 microns and 1.6% moisture provided increased ileal digestibility of amino acids and AMEn in the starter period. However, the expanded feed improved pellet quality and feed conversion of broilers at 42 days of age. We conclude that factors such as moisture, particle size and processing affect the pellet quality, and therefore should be considered when attempting to optimize broiler performance.

Application of Ultra-Small Micro Grinding and Micro Milling Tools: Possibilities and Limitations.

Current demands for flexible, individual microstructures in high quality result in high requirements for micro tools. As the tool size defines the minimum structure size, ultra-small tools are needed. To achieve tool diameters of 50 µm and lower, we investigate the complete manufacturing chain of micro machining. From the development of the machine tools and components needed to produce and apply the micro tools, the micro tools themselves, as well as the micro machining processes. Machine tools are developed with the possibility of producing the micro geometry (cutting edge design) of micro tools as well as plating processes to produce super abrasive micro grinding tools. Applying these setups, we are able to produce ultra-small micro grinding and micro milling tools with typical diameters of 50 µm and down to 4 µm. However, the application of such tools is very challenging. The article presents possibilities and limitations in manufacturing the micro tools themselves as well as microstructures made with these tools. A special emphasis will be on the influence of the tool substrate in micro milling and grain sizes in micro grinding.

The Effect of Sugarcane Bagassès Size on the Properties of Pretreatment and Enzymatic Hydrolysis

The influence of milled bagasse particle size on their reducing sugar and lignin content during dilute acid hydrolysis followed by enzymolysis was investigated. The biomass crystal structures of hydrolyzed residues and enzymolyzed substrates were studied with X-ray diffractometry (XRD). The results showed that the conversion ratio of reducing sugar declined with decreasing milled bagasse particle size. The conversion ratio of reducing sugar after acid hydrolysis decreased from 31.3% to 28.9%. The smaller of the milled bagasse particle size was, the higher of the klason lignin content of hydrolyzed residuals was, which resulted in a decline in conversion ratio of reducing sugar during enzymolysis. In this study, the optimal size of milled bagasse particles was 10 to 20 meshes. The total reducing sugar conversion ratio was 61.5%, consisting of 31.3% in hydrolysis and 30.2% in enzymolysis. After hydrolysis, the specific surface area and pore size increased, and the fiber length was shortened. The inner microfiber bundles were exposed, which improved the accessibility of cellulase and the efficiency of enzymolysis.

Evaluating the effect of feed particles size and their hardness on the particle size distribution of semi-autogenous (SAG) mill’s product

ABSTRACTThe main target of this research was to provide the optimal size of mills’ feed with acceptable accuracy, in order to find the size range of particles to achieve the maximum grinding product. Nowadays, experimental semi-autogenous (SAG) mill and drop-weight test are used for evaluation of grinding circuit regarding changes in feed particle size distribution, size of the ball, speed of mill, prediction of energy required, and product size distribution for complete grinding in AG and SAG mills. In this study, the effect of initial size ranges of feed (+13.2–315 mm) on the amount of grinding product and its size distribution has been evaluated, in order to find the size range of particles to achieve the maximum grinding product. The results showed that the feed size range of 19–22.4 mm had the highest amount of grinding product and breakage index number in different energy levels and the validity of results was evaluated with ball drop-weight test, as well.

Cu-Ti-B Composite Powder Prepared by Mechanical Alloying

Taking Cu, Ti and B powder as raw material, Cu-Ti-B composite powder was prepared by mechanical alloying (MA). The phase, microstructure of the powder during MA process was studied by XRD and SEM, and combining the flour yield to study the best ball mill time. The result shows that: Early ball milling, powder particle size drops rapidly. Extruding and shearing force between grinding balls, plastic deformation of sheets. After 15h, XRD diffraction peak intensity decrease stabilize, particle size reduce to around 20 um. Ball milling after 20 h, powder refining trend slowing, produce powder together. Considering the efficiency of ball milling and powder particle size requirements, determine the best ball milling time for 15 h.

Cu-Ti-B Composite Powder Prepared by Mechanical Alloying

Taking Cu, Ti and B powder as raw material, Cu-Ti-B composite powder was prepared by mechanical alloying (MA). The phase, microstructure of the powder during MA process was studied by XRD and SEM, and combining the flour yield to study the best ball mill time. The result shows that: Early ball milling, powder particle size drops rapidly. Extruding and shearing force between grinding balls, plastic deformation of sheets. After 15h, XRD diffraction peak intensity decrease stabilize, particle size reduce to around 20 um. Ball milling after 20 h, powder refining trend slowing, produce powder together. Considering the efficiency of ball milling and powder particle size requirements, determine the best ball milling time for 15 h.

Niobium Carbide-Reinforced Al Matrix Composites Produced by High-Energy Ball Milling

Aluminum and its alloys are key materials for the transportation industry as they contribute to the development of lightweight structures. The dispersion of hard ceramic particles in the Al soft matrix can lead to a substantial strengthening effect, resulting in composite materials exhibiting interesting mechanical properties and inspiring their technological use in sectors like the automotive and aerospace industries. Powder metallurgy techniques are attractive to design metal matrix composites, achieving a homogeneous distribution of the reinforcement into the metal matrix. In this work, pure aluminum has been reinforced with particles of niobium carbide (NbC), an extremely hard and stable refractory ceramic. Its use as a reinforcing phase in metal matrix composites has not been deeply explored. Composite powders produced after different milling times, with 10 and 20 vol pct of NbC were produced by high-energy ball milling and characterized by scanning electron microscopy and by X-ray diffraction to establish a relationship between the milling time and size, morphology, and distribution of the particles in the composite powder. Subsequently, an Al/10 pct NbC composite powder was hot extruded into cylindrical bars. The strength of the obtained composite bars is comparable to the commercial high-strength, aeronautical-grade aluminum alloys.