Rod Mill Research Articles

The effect of smelting and granulation on some properties of smelter slag

The technogenic copper deposit of slag Depo 1 is located in the industrial district of the Smelter and Refineries of RTB Bor. Exploitation reserves are 9 190 940 t of slag with the average copper content of 0.715%. Sample of this deposit was melted in a furnace and then cooled with a jet of water when it was poured into a thin jet, whereby the small - granulated pieces were formed. Comparison of some properties of this sample was done with the sample in the form in which it was deposited in the deposit. This paper presents the chemical analysis, SEM - EDS analysis, Bond working index in a rod and ball mill, grinding kinetics and experiments of flotation concentration of copper depending on the grinding fineness in the range of 60 - 95% - 0.075 mm.

A Study on Elimination of Defects for Enhancement of Cost-Effectiveness in Wire Rod Mills in Indian Scenario

A Study on Elimination of Defects for Enhancement of Cost-Effectiveness in Wire Rod Mills in Indian Scenario

Application of stirred mill to upgrading of graphite concentrate by flotation

ABSTRACTIt is difficult to obtain high-grade concentrates for layered minerals, such as graphite, by mineral processing due to the existence of impurities between interlayers. Conventional grinding mills are inefficient in liberating the mineral layers. Upgrading a graphite concentrate by re-grinding with a designed stirred mill is investigated in this paper. Better liberation of mineral layers was achieved, compared with a ball mill and a rod mill. Through re-grinding with the stirred mill followed by a two-stage cleaning flotation process, a low-grade graphite concentrate containing 84.59% fixed carbon could be refined to a high-quality concentrate containing 98.62% fixed carbon with a graphite recovery of 94.15%. It is demonstrated that the stirred mill is more suitable for selective grinding, mineral flake protection and upgrading of layered minerals.

An effective approach to synthesize carbon nanotube-reinforced Al matrix composite precursor

Abstract Aluminum-based nanocomposites reinforced with carbon nanotubes have increased scientific attention in today’s life. The dispersion quality was the critical aspect, which decides the homogeneous distribution of CNTs within the Al matrix as starting precursors. In this study, a new attempt has been made to obtain a uniformly dispersed Al-0.75% CNT precursor via combining ultra-sonication, cubic tumbler rod milling, and spray drying. This process was integrated with organic deflocculant (formulator) in specific proportion to transform as a semi-wet-based route. The effect of milling media on the morphology and interface structure of the as-produced composite precursor after all the processing steps was investigated through scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy. The results reveal that the approach is effective in CNT dispersion in Al precursor, which shields the nanotube structure from damage for longer periods of milling time due to the organic formulator mixture, and also, the CNT retention in the Al precursor with minimum clustering is identified compared to the ball milling process. Carbon traces were confirmed in the as-produced composite precursor by this approach.

Effect of grinding media on the surface property and flotation behavior of scheelite particles

Grinding for mineral liberation is a prerequisite for a successful flotation separation. Different grinding media produce mineral particles with different surface properties and flotability. In this study, the surface properties and flotation behavior of scheelite particles having a size of −74+38μm produced by ball and rod mills were studied through single mineral flotation experiment, scanning electron microscopy (SEM) observation, wettability measurement, and X-ray diffraction (XRD) test. The wettability and flotation results showed that, compared to the ball mill particles, the rod mill ones have a lower critical surface tension and thus a greater hydrophobicity when treated with the collector solution, and accordingly perform a better flotation recovery using oleate as the collector. In addition, the rod mill particles have a smaller specific surface area, so the full monolayer adsorption of the collector on their surfaces is achieved at a lower oleate concentration. The SEM analysis further confirmed that mineral grains obtained from the rod mill possess larger elongation and flatness values, which are essentially required for their attachment with air bubbles. The XRD observations revealed that mineral particles from both mills (i.e. ball and rod) have similar exposure intensity of abundant {112} surface. However, the rod mill particles have more {101} surface exposed, while the ball mill particles have more {001} surface exposed, leading to a stronger interaction of the collector with the rod mill particles. Keeping in view the stronger interaction with the collector and the easier attachment to air bubbles, the rod mill scheelite particles are deemed to be more hydrophobic and have a higher flotation recovery. These details studied will help establish the relation between the particle surface properties and the grinding media, and provide guidance for optimizing flotation separation.

Material Tracking with Dynamic Torque Adaptation for Tension Control in Wire Rod Mill

Material tracking is an important part of the automation control system which has a major impact on the product quality. This paper addresses a stand load identification in wire rod mill as a new algorithm added to existing control system. Tension control approaches are described and a modification of existing tracking system is proposed in order to eliminate tracking faults. Proposed method is based on dynamic torque calculation and its performance was experimentally verified on the industrial wire rod mill. Experimental results show significant reduction of the errors.

Characterization of the Gold Ore to Acquire an Optimum Degree of Liberation

Gold ore processing is often ineffective in obtaining gold metal. Various methods have been successfully developed on an industrial scale, but small-scale gold mines are often problematic. The problem of inefficiency of processing is caused by gold ore characterization and evaluation of gold ore preparation process is not implemented. In this study, the conditions of gold ore deposits have a thin thickness (vein). These gold ore deposits have an economic value if they are developed by traditional gold mining. The objective of the research is to identify and characterize gold ore as well as to analyze the optimum condition to obtain the perfect gold mineral liberation degree. Research methods include characterization of gold ore geology, sampling for test preparation using rod mill (amalgamation), gold mineral liberation using time variables and number of rods. After the grinding process, grain size analysis is performed with various mesh sizes, and the analysis of each fraction uses a polarization microscope. The results show that goldore minerals are associated with pyrite, chalcopyrite, galena and gangue minerals. Gold minerals are fully liberated at a certain size. The results of this research are very useful for the gold ore grinding process to obtain an efficient gold processing

Development of the probabilistic model of grinding as applied to rod mills operation

Development of the probabilistic model of grinding as applied to rod mills operation

IMPROVEMENT OF THE PRODUCTION EFFICIENCY OF REINFORCEMENT SECTIONS AT THE OPERATING CONTINUOUS SMALL-SECTION MILL

The article considers a promising combined method for increasing the production effi ciency of the section rolling profi les – rollingdivision with the use of non-powered dividing tool, the experience in the use of which in the conditions of production has shown high effi - ciency of this direction in terms of reducing the cost of the fi nished product. The dependences, which allow to defi ne the frequency separation, and high-speed conditions when deciding industrial introduction of process technology of rolling-separation on current continuous small-section mill 250. The existing experience of implementing the rolling process-separation model of continuous small-grade mill 250 has been reviewed, which allowed to reveal the peculiarities in the distribution coeffi cients of drawing and changing speed conditions for groups of stands. It was found that on the basis of capacity of rolling equipment on the mill, it is advisable to carry out the longitudinal separation of the workpiece into two bands in the fi nishing group of stands, and changes in the total coeffi cients of drawing and rolling speed on rolling groups were also identifi ed. The article presents data on changes in the machine time for reinforcing the profi le no. 10, no. 12, no. 14 in connection with the development of technology in the process of rolling-division, which in turn contributed to increasing eff ectivelySTI production of existing continuous small-section mill. Proven in the industry values of the total coeffi cients of drawing and rolling speed on rolling groups can be determined from the shown illustrations. In addition, the study process was carried out for experimental – industrial rolling of rebar no. 8 under conditions of continuous light section mill 250-1 of the rolling shop of JSC “EVRAZ ZSMK”. The authors have compared the coeffi cients of drawing and rolling speed in the production of rebar no. 8 on the continuous wire mill 250 and a continuous small-section mill 250 from the same piece – square 100 mm. The results are provided in the illustration, which shows that the use of the rolling process-separation allows to use four stands less than at the rod mill at production of rebar no. 8 at a small-section mill.

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

ABSTRACTIn 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.

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst.

A method for the solvent-free photocatalytic conversion of solid and liquid substrates was developed, using a novel rod mill apparatus. In this setup, thin liquid films are realized which is crucial for an effective photocatalytic conversion due to the low penetration depth of light in heterogeneous systems. Several benzylic alcohols were oxidized with riboflavin tetraacetate as photocatalyst under blue light irradiation of the reaction mixture. The corresponding carbonyl compounds were obtained in moderate to good yields.

The protective mechanism of docosahexaenoic acid in mouse model of Parkinson: The role of heme oxygenase

Parkinson's disease (PD) is characterized by degeneration of the dopaminergic neurons in substantia nigra (SN). Its major clinical symptoms are tremor, rigidity, bradykinesia and postural instability. Docosahexaenoic acid (DHA) is an essential fatty acid for neural functions that resides within the neural membrane. A decline in fatty acid concentration is observed in case of neurodegenerative diseases such as PD. The present study aimed to explore the role of the heme oxygenase (HO) enzyme in protective effects of DHA administration in an experimental model of PD by using the neurotoxin 1-Methly-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).Three-month old male C57BL/6 mice were randomly divided into 4 groups as Control, DHA-treated (DHA), MPTP-injected (MPTP) and DHA-treated + MPTP injected (DHA + MPTP). DHA was administered daily (36 mg kg−1 day−1) by gavage to DHA and DHA + MPTP groups for 30 days. On the 23rd day of DHA administration, MPTP was intraperitoneally injected at a dose of 4 × 20 mg kg−1 with 2-hr. intervals.Motor activities of mice were evaluated by pole test, locomotor activity and rotarod tests on the 7th day of the utilization of experimental Parkinson's model. Total brain tissues were used in immunohistochemical analysis of the tyrosine hydroxylase (TH) and Nuclear factor E2 related factor2 (Nrf2). SN tissues were extracted for biochemical analysis. HO-1 and HO-2 protein levels were detected by western blotting. Further, HO activity was measured by spectrophotometric assay.As an indicator of motor coordination and balance, the rotarod test at 40 rpm showed that MPTP-treated animals exhibited shorter time on the rotating rod mill, which was significantly increased by DHA treatment in DHA + MPTP group. The total locomotor activity, ambulatory movement and total distance were decreased in MPTP group, whereas they were improved upon DHA treatment. The results of the pole test indicating the intensity of the bradykinesia showed that the T-turn and T-total were increased in MPTP group, while DHA treatment significantly shortened both parameters.The number of TH-positive cells in SN was significantly reduced in MPTP group compared to the Control and DHA + MPTP groups. Also, immunoreactive Nrf2 levels were clearly increased in MPTP group compared to DHA + MPTP group. HO-1 expression level decreased in the DHA + MPTP group compared to MPTP group.The results of the present study indicated that DHA has protective effects on dopaminergic neurons in MPTP-induced experimental model of PD. In addition, the pathways of HO-1 and HO-2 might participate in this protective mechanism.

Models for Rod and Bar Rolling Mills with 2‑roll, 3‑roll, and 4‑roll Stands

For the quality of rolled products, a perfect surface quality and tight, close tolerances apart from defined mechanical properties are essential. One key condition is a perfect pass design in the rolling mill. The paper deals with the models for a pass design calculation as well as a calculation of roll force and power demands for the rolling mill. On modern bar and rod mill, different types of mill stands are used, with 2‑roll, 3‑roll, and 4‑roll stands. For each of these stand types, a special model system is used for the calculation. Heat balance and temperature control by water cooling are the basis for thermomechanical rolling to achieve the desired mechanical properties of the material. Free size rolling and the compensation of the numerous influencing parameters on the product dimensions must be incorporated in a pass design.

Reducing mercury usage in artisanal gold mines using grinding and sieving

Gold extraction in primitive artisanal mines usually involves the over-usage of mercury (Hg). This practice results in significant environmental contamination, but is difficult to eliminate due to its effectiveness. Any alternative must be simple, inexpensive and visually effective. This paper proposes a novel, chemical-free method for extracting gold from gravity middlings which has potential as an effective alternative to Hg amalgamation. This method exploits the differences in relative malleability, rather than density, of gold and waste products by submitting concentrates to grinding in a rod mill. The grind products are separated through a sieve, where flattened gold particles are captured on the oversize while brittle waste reports to the fines. Recoveries often exceeded 90%, with nearly pure raw gold separated after only minutes of grinding. While recently adapted to the modern Yukon placer fields, this method has potential to reduce Hg usage by miners in more primitive settings.

Assessment of Exposure to Noise of Workers to a Reinforcing Bar Rod Mill ArcelorMittal Algeria

AbstractThis work is a contribution to a normative approach of noise assessment in the professional environment. It permits the identification of the affected workstations on the one hand and on the other hand it constitutes an important support to the preoccupations of the impact study on the environment in plants. It also informs us on the adequate preparation of the procedures required by the Environmental Management System (ISO 14001) being implemented in steel-making complex ArcelorMittal Algeria. It constitutes an answer to the recommended environmental politics.The proposed calculation methods are verified according to the recognized sources (ISO 9612, 2009) and the results will be estimated in relation to the legal thresholds recommended by international bodies. The methodology for measuring the noise exposure levels has been done according to the following steps: work analysis; selection of measurement strategy; measurements; error handling and uncertainty evaluations; calculations; and presentation of results. This will lead us to an implementation of a corrective and preventive action plan intended to master this occupational risk carrying prejudice to the health of the workers.

Bauxite grindability at elevated temperature in various mills

The present paper deals with the grindability experimental results of an Australian bauxite sample in the Universal Hardgrove mill, the Universal Bond ball mill and the heat insulated Bond Rod Mill in the temperature range from 20 up to 80°C. As previously observed the grindability of the bauxite has improved at elevated temperature. The specific grinding energy decreased. Correlation between the Bond Work Indices calculated from three different method (HGI, Bond Ball Mill Work Index and Bond Rod Mill Work Index) was established. Appropriate correlation in the investigated temperature interval was found. Pore size distribution, SEM and BET results show that in spite of the good correlation between the grindability characteristics, the material properties of the ground products have significant differences. Namely, the various grinding stresses resulted in different material pore size distribution and specific surface area.

Exploiting the malleability of gold for placer concentrate extraction and recovery

A novel, chemical-free method for extracting gold from gravity middlings is described. This method exploits the differences in relative malleability, rather than density, of gold and waste products by submitting concentrates to grinding in a rod mill. The grind products are separated through a sieve, where flattened gold particles are captured on the oversize while brittle waste reports to the fines. This paper presents the results of a field tour of this method throughout the Yukon placer gold fields, where gold was extracted from difficult to process stockpiled middlings. Recoveries were often well over 90%, with nearly pure raw gold effectively separated after only minutes of grinding in a batch mill. Gold remaining in the fine and evenly classified loss material is now more amenable to gravity processing than similarly sized unground concentrate. Further lab testing indicated that gold recoveries were most sensitive to the mill charge amount and total grind time. While these results are based on placer properties, the method has potential in any mill involving a gravity recovery circuit.

Effect of different grinding conditions on the dissociation and flotation of difficult-to-float coal

ABSTRACTThe recovery of clean coal can be improved through grinding. In this study, grinding and flotation experiments were conducted on difficult-to-float coal. Results show that the particle size obtained from ball milling is finer than that obtained from rod milling. However, the particle size distribution obtained from rod milling is more evenly distributed than that obtained from ball milling. The contact styles of steel rod and steel ball are “line contact” and “point contact,” respectively. Results from the flotation experiments are consistent with those from the orthogonal experiments.

Development of ball mill test for simulation of industrial circuit

The Bond method for ball mil designing has been used for 60 years. Based on the Work Index test, such method is applied mostly in traditional circuit configuration, which includes multi-staged crushing, followed by rod and ball milling. On the other hand, simulation is a widespread and used technique for comminution, classification modeling, and simulation. Even though both methods are complementary, there is no effective integration between them. This work shows a technique designed to integrate both energy and modeling approaches for estimating and improving ball mill grinding performance. The work is based on industrial data survey results, as well as on laboratory testing, the latter developed specifically for such a purpose. The technique was validated under an industrial environment for assessing the obtained results.

An Approach to Heat Transfer Analysis of Wire Loops Over the Stelmor Conveyor to Predict the Microstructural and Mechanical Attributes of Steel Rods

To understand and predict the microstructure evolution in various grades of steel, a heat transfer coupled with phase transformation model has been formulated with an enhanced stelmor cooling module. This module is capable of handling both blower assisted high cooling and retarded cooling using hoods. The stelmor module incorporates the change in ring spacing of the wire loops on the stelmor due to a change in mill speed and conveyor speed of the wire rod mill. A geometrical approach to convective and radiative losses taking into account the void fraction and shape factor of wire loop is reported. This makes the model robust by strengthening the heat transfer formulation. This paper deals with the correlation of wire rod mill process parameters on the cooling curve of wire rods. The cooling of wire rods is dependent on the stelmor operating parameters. Commercial high carbon grades require high capacity blowers for efficient cooling to refine the pearlite microstructure and impart greater strength. Welding grade wire rods (low carbon grades) on the other hand require retarded cooling to increase the ferrite grain size and decrease the ultimate tensile strength.