Industrial Ball Mill Research Articles

Application of an industrialized ultrafine composite powder in cement-based materials: Hydration characteristics, microstructure, and corrosion resistance

To reduce the reliance on cement clinker, employing ultrafine powders as supplementary cementitious materials (SCMs) is gradually gaining importance. This study investigated the effect of an ultrafine composite powder (UCP) having a specific surface area of approximately 730 m²/kg, produced by industrial ball milling ordinary blast furnace slag and fly ash at a 1:1 ratio, on cement hydration and its durability. The ultrafine composite powder was characterized by X-ray fluorescence spectrometer (XRF), X-Ray diffraction (XRD), particle size analyzer, and scanning electron microscope (SEM). The effects of ultrafine composite powder on the macroscopic properties of cement-based materials were assessed through flowability tests, setting time tests, and mechanical properties tests. Then, the hydration heat release, hydration products and microstructures of the pastes were characterized using isothermal calorimetry, XRD, thermogravimetric (TG), SEM and mercury intrusion porosimetry (MIP). Finally, the effects of ultrafine composite powder on the durability of cement-based materials were evaluated by electrical flux, chloride diffusion coefficient, and mechanical properties tests. The results showed that ultrafine composite powder enhanced the flowability of cement paste under the synergistic effect of superplasticizer. However, the setting time was prolonged due to the dilution of cement by ultrafine composite powder. The ultrafine composite powder significantly improved the early mechanical properties of the mortar, and the mechanical properties after 28-days was equivalent to that of the control. The ultrafine composite powder could significantly decrease the cumulative heat release of cement paste. Due to the high SO3 content, an additional exothermic peak representing ettringite formation was observed. As the hydration time extends, the hydration products in the paste changed, especially the transformation from ettringite to kuzite, and the formation of hemicarbonate and monocarbonate. As the ultrafine composite powder content increases, the proportion of gel micro-pores increased, whereas the proportion of middle and large capillary pores decreased. Consequently, the total pores in the paste also decreased. The addition of ultrafine composite powder enhanced the durability of the cement-based materials, making it an ideal choice for use in coastal engineering projects.

Simulating large-diameter industrial ball mills from batch-grinding tests

Phenomenological models of ball milling are routinely used to optimize size reduction operations. A usual method adopted in the minerals industry relies on batch-grinding tests to calibrate models in a population balance model formulation describing the breakage behaviour and then scale-up the breakage parameters using an energy-based relationship. Despite the important advances and application of these methods, their application in describing grinding in large-diameter (>7.5 m) mills has not been widely demonstrated. The work demonstrates the calibration of industrial-scale ball mill model parameters from laboratory milling tests on Platinum Group Metals (PGM) and Itabirite iron ores. Minor fine-tunning of a single model parameter was required to simulate the large-diameter industrial mills, demonstrating the validity of the approach for ores as distinct as PGM and Itabirite iron ores. Estimation of the Arbiter Flow Number below 4.1 showed a regular slurry transport for all mills studied. This model can then be used in optimization of the ball mill performance.

Selection of Organic Coating Systems for Corrosion Protection of Industrial Equipment

The most important element of corrosion protection in industrial conditions is the protective coating system. However, selecting the right coating can often be a real problem due to the sheer number of coating manufacturers and their products on the market. A quantitative approach based on the data mining technique used to analyze the obtained multi-site exposure data has been proposed. This was demonstrated by the example of the selection of a coating system to protect an industrial ball mill located in a hall for the enrichment of copper ore at the Polish company KGHM Polska Miedz S.A. A collection of 21 two-layer coating systems from different manufacturers was tested for one year. Multiple areas on the industrial ball mill, subjected to varying degrees of vibrations and abrasion, were painted. In addition, sets of samples that can be detached from the mill housing were mounted, as well as the set exposed in the hall without vibrations. The condition of the coatings after exposure was assessed using impedance spectroscopy. The obtained data from many different exposure areas were analyzed using principal components analysis (PCA). In this way, the most advantageous coating systems for the specific conditions in the hall were indicated. Additionally, on this basis, the contribution of various destructive factors, including vibrations and abrasion, to the protective properties of the tested coatings, was estimated.

Investigation of the effect of industrial ball mill liner type on their comminution mechanism using DEM

The mill shell liner type, rotation speed and the amount of its loading are the key factors influencing the charge behavior, consequently the comminution mechanism. In this paper, milling operation of industrial ball mills using Discrete Element Method (DEM) is investigated. First, an industrial scale ball mill with a Smooth liner type is simulated. Then, by changing liner type, i.e. Wave, Rib, Ship-lap, Lorain, Osborn, and Step liners, six other independent simulations are performed. Effects of mill shell liner type on charge shoulder, toe, impact, and head points, also on head height and impact zone length as well as on creation of cascading, cataracting, and centrifuging motions for balls at two different mill speeds, i.e. 70% and 80% of its critical speed (NC) are evaluated. Also, in order to validate simulation results, a laboratory scale mill is simulated. The results indicate that the charge heads are respectively about 240.13, 283.40, 306.47, 278.12, 274.42, 274.42, and 278.12 cm at the simulations performed with Smooth, Wave, Rib, Ship-lap, Lorain, Osborn, and Step liners at 70% of NC. The corresponding values at 80% of NC are as follows: 256.08, 264.56, 313.54, 298.45, 313.54, 311.60, and 283.40 cm. On the other hand, the impact zone lengths are respectively about 33.14, 22.11, 38.63, 35.86, 38.63, 38.63, and 49.59 cm at the simulations performed with above-mentioned liners at 70% of NC. The corresponding values for impact zone lengths at 80% of NC are as follows: 35.86, 27.63, 49.59, 38.63, 33.14, 52.32, and 41.38 cm. Comparison of the simulations related to the laboratory scale mill with experimental results demonstrates a good agreement which validates the DEM simulations and the software used.

Mechanistic modeling and simulation of grinding iron ore pellet feed in pilot and industrial-scale ball mills

Various approaches have been used over the years to describe quantitatively ball milling, with different levels of success. The present work presents the application and validation of a mechanistic model to describe ball milling of iron ore pellet feed. The approach started by estimating selected parameters describing the ore characteristics by back-calculation from batch grinding tests, followed by validation of the model in batch grinding as well as continuous open-circuit ball milling at a pilot-scale operating at a variety of solids concentrations, both with overflow and grate discharge. An industrial ball mill was then laser scanned and surveyed, including measurements of residence time distribution. Simulations using the discrete element method were then conducted and the model was applied to simulate closed-circuit operation, resulting in good agreement between measured and predicted size distributions and circulating load ratio.

Effects of Mill Speed and Air Classifier Speed on Performance of an Industrial Ball Mill

Nowadays, ball mills are widely used in cement plants to grind clinker and gypsum to produce cement. The research focuses on the mill speed as well as air classifier speed effect on the two compartment Cement ball mill performance in terms of Blaine, Sulphur trioxide contents, mill power, mill residue and mill residence time. Special importance was assigned to the study of the specific surface area and the surface area production rate, both during the variation with the mill speed and the air classifier speed. Within the content of this work, sampling campaigns were organized around a cement grinding circuit and varying cement ball mill speed as well as an air classifier speed at various dosage feed rate. The fact that such an examination has not been made previously by using industrial data rather than lab scale makes this work unique. The fineness is measured in terms of Blaine number. Mill speed and air classifier speed were the investigating parameters. It was deduced that depending on the speed of mill and air classifier, their effects on Blaine, SO3, mill power and mill performance were varied, ultimately all of them improved the performance of grinding and classification operations. The rapid expansion of ceramic wastes in China has raised great many interests in their sustainable uses in building materials The micro ceramic powder can be taken as a supplementary cementitious material to replace cement up to 40% for tuning the microstructure and mechanical properties of blend cement materials. The Blaine quality dictates strength, setting time and overall performance of cement. Optimum performance of ball mill could potentially refine Blaine fineness, thereby improving the cement quality. This study investigates the effects of separator speed and mill speed on Blaine fineness, mill residue, consumed power. Five speed levels used in closed cycle grinding mill are 200, 400, 600, 800 and 1000 rpm. The capacities were determined to obtain product Blaine surface areas in the limits between 2000 cm2 / gram and Variations in clinker feed rate, mill speed and separator speed could proportionally impact the grain quality of Blaine. When the separator speed is increased from 850 to 900 rpm the Blaine is increased from 2800 to 3000 cm2/g and mill residue decrease from 15 to 10 microns. Therefore, optimum parametric combination could reduce power consumption while improving the cement quality. Knowledge of effects of parametric variations on the quality of end product could be helpful for controlling product quality. Furthermore, proper grinding of clinker produces fine Blaine at first place and reduces the need for recycling of coarse grains.

Comparison of particle size and shape distribution of corundum produced by industrial ball mill and material bed compression

Comminution of corundum is a challenging task, as it has very high hardness and compression strength, and it is also a very abrasive material. Selection of the best comminution process for each particle size thus has a great importance. But for this, first we must understand the effects of different type of stresses and comminution methods used for the dry comminution of corundum. In this article the comparison of particle size and shape distribution of corundum produced by material bed compression and classic ball mill grinding is carried out. Comminution experiments were carried out in a laboratory scale piston press, to achieve material bed compression like in HPGR technology, and in a conventional industrial scale ball mill for particle-particle, particle-grinding media interaction. The results showed that the products of the two comminution methods have a significant difference both in particle size and shape distribution.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ПРОЦЕССА КЛАССИФИКАЦИИ МАТЕРИАЛА В КЛАССИФИЦИРУЮЩЕЙ ПЕРЕГОРОДКЕ ШАРОВОЙ МЕЛЬНИЦЫ

Ball mills are widely used for dispersion of materials in various industries, as they are characterized by ease of maintenance, operation and sufficiently high performance. To improve the process of inner-chamber classification of coarse-ground material, a new construction of the classifying partition with blades having cylindrical screening surfaces is proposed. The aim of the research is to substantiate the effectiveness of the application of the developed construction of the classifying partition in an industrial ball mill. The tasks of the research are to study the effectiveness of the developed construction of the classifying partitions on industrial ball mill. The tasks are solved of constructing and analyzing a regression equation that adequately describes the efficiency of the process of classifying coarse material with a cylindrical sieving surface depending on variable factors, determining rational areas of their values; comparing the efficiency of using blades with cylindrical and flat screening surfaces for inner-chamber classification of coarse material; confirmation of the possibility of providing the developed classifying partition with the mass productivity necessary for the operation of the mill. In the course of the work, the methods of simulation and mathematical modeling were used. As a result of the study, the efficiency of using a classifying partition with blades with cylindrical screening surfaces of a ball mill D×L=2×10,5 is substantiated.

An innovative approach for determining the grinding media system of ball mill based on grinding kinetics and linear superposition principle

Herein, an innovative approach for determining the grinding media system of ball mill based on grinding kinetics and linear superposition principle was proposed. The optimal media ball size of −2 + 0.45 mm, −0.45 + 0.15 mm, and − 0.15 mm feeding samples were 40 mm, 30 mm, and 30 mm, respectively. According to the linear superposition principle, the media size ratio is equal to the yield of ores. The optimal media proportion was φ 50 mm: φ 40 mm: φ 30 mm = 28%: 28%: 44% via wet grinding experiment, in which the yield of qualified granular material (−0.074 + 0.03 mm) suitable for beneficiation was the largest in the ground products. The optimized space-filling factor and material media ratio was 35% and 1.0 through the wet grinding experiment. According to the energy consumption method, the mathematical function models of installed power and mill productivity vs. space-filling factors were established to calculate the installed power and productivity of an industrial ball mill (Φ5.03 m × 6.40 m).

STUDYING THE EFFECT OF ORE TEXTURE ON THE BOND WORK INDEX AT THE MAHD AD DAHAB GOLD MINE: A CASE STUDY

The grinding process in industrial ball mills is the basic unit and most energy-consuming component. Therefore, great economic gains will be achieved if a slight improvement occurs in the efficiency of grinding. The variation of gold ore petrography affects its mechanical properties which in turn, affects the grinding process. In this investigation, different gold-bearing ore types from the Mahd Ad Dahab gold mine were tested. As a part of the current study, some of the me- chanical and physical properties including strength properties, geological characterization and Bond work index were determined. This investigation showed that the Bond work index increases with an increase in rock strength properties. The maximum difference in the Bond work index for the five tested gold ores was 11%. Whereas, an average interval between the two-sequence types of the tested ore was approximately 2.5%.

Power-draw prediction by random forest based on operating parameters for an industrial ball mill

Estimation of mill power-draw can play a critical role in economics, operation and control standpoints of the entire mineral processing plants since the cost of milling is the single biggest expense within the process. Thus, several empirical power-draw prediction models have been generated based on a combination of laboratory, pilot and full-scale measurements of different milling conditions. However, they cannot be used in industrial plants, where in full-scale operations, only not few numbers of input parameters used in those models are measured. Moreover, empirical models do not assess the relationship between input features. This investigation is going to introduce random forest (RF), as a predictive model, beside of its associated variable importance measures system, as a sensible means for variable selection, to overcome drawbacks of empirical models. Although RF as a powerful modeling tool has been used in several problem solving systems, it has not comprehensively considered in the powder technology areas. In this investigation, an industrial ball mill database from Chadormalu iron ore processing plant were used to develop a RF model and explore relationships between power-draw and other monitored operating parameters. Modeling results indicated that RF can highly improve the prediction accuracy of power-draw as compared to the regression as a typical method (R2: 0.98 vs. 0.60, respectively) and rank operational milling parameters based on their importance.

Investigation grindability of portlandcement in industrial ball mills

Investigation grindability of portlandcement in industrial ball mills

A survey on troubleshooting of closed-circuit grinding system

ABSTRACTAn industrial ball mill operating in closed-circuit with hydrocyclones was studied by five sampling surveys. The aim of the present study was to optimise operating parameters (i.e. charge volume, make-up ball size regime, slurry mean residence time, number of hydrocyclones in operation and hydrocyclone’s feed solids content (Sf)) with respect to increasing throughout from 225 to 300 tons per hour (tph). The obtained results showed that increasing charge volume from 32 to 39% led to producing approximately 9% finer product size (P80). Binary ball size regime rather than using mono-sized balls resulted in reduction of the P80 relatively 5%. The Sf was identified as the most effective parameter on grinding efficiency. The cut-size plunged dramatically from 130 to 90 μm by reduction of Sf from 54 to 48%. Finally, it was concluded that the capacity of grinding circuit could be practically increased to 300 tph if all relevant parameters fell into the optimised ranges.

Determination of the granulometric composition parameters of the grinding product in a ball mill

The article deals with the issue of the formation of the grain composition of the comminuted material inside the drum of a ball mill. The approach to the calculation of the grain composition at its transition from a larger fraction from a smaller fraction is presented. The proposed approach was tested on an industrial cement ball mill and confirmed on an experimental installation. This approach allows you to determine the parameters of the kinetics of grinding, depending on the design parameters used ball mills.

A new statistical view to modeling of particle residence time distribution in full-scale overflow ball mill operating in closed-circuit

ABSTRACTIn the present study, residence time distribution (RTD) of an industrial ball mill operating in closed-circuit with hydrocyclones was measured. Several probability distribution functions (PDFs) constituting exponential, Weibull, Gamma, logistic, normal, and lognormal were applied to obtained RTD results and evaluated based on Anderson-Darling statistic (AD) and associated p-value indices. In addition, three most common empirical RTD models (i.e., perfect mixer, N-Mixer and Weller) were fitted to the given practical data. Aside from assessment of coefficient determination (R2) for each model, a factor of incorporating the number of model parameters was considered using Bayesian information criterion, low of iterated logarithm criterion and Akaike information criterion. It was revealed that Weibull PDF is fitted reasonably well to the measured experimental data compared with the other PDFs. Despite the relative variance (σ2) of N-Mixer model was slightly less than the corresponded value of Weller model, the goodness of fit criterion (R2) and all four information criteria (IC) showed better results for Weller model. Therefore, one large with two small tanks in series along with a dead time was selected as the best model from the statistical point of view. Finally, it was concluded that the RTD models must be evaluated not only on the basis of goodness of fit but also the number of model parameters should be taken into account.

Investigation of laboratory conditions effect on prediction accuracy of size distribution of industrial ball mill discharge by using a perfect mixing model. A case study: Ozdogu copper-molybdenum plant

Investigation of laboratory conditions effect on prediction accuracy of size distribution of industrial ball mill discharge by using a perfect mixing model. A case study: Ozdogu copper-molybdenum plant

Performance optimization of an industrial ball mill for chromite processing

Performance optimization of an industrial ball mill for chromite processing

Scalable Preparation of LiFePO4/C Nanocomposites with sp2‐Coordinated Carbon Coating as High‐Performance Cathode Materials for Lithium‐Ion Batteries

AbstractWe hereby report carbon‐coated LiFePO4 cathode materials prepared by industrial ball milling and a solid‐state reaction with Li2CO3, NH4H2PO4, and FeC2O4⋅2 H2O as starting materials. Soluble starch as the primary carbon source was investigated for its capability of generating a highly graphitic carbon coating, whilst sufficiently controlling the crystal growth of LiFePO4. XRD analysis, Raman spectroscopy, and electrochemical testing revealed the significant impact of the amount of starch added to the pre‐sintered precursor on phase purity, carbon quality, and electrochemical performance of the final LiFePO4/C composite. The optimum soluble starch content to achieve a highly sp2‐coordinated carbon coating is 10 wt %, which enabled our LiFePO4/C composite to achieve competitive reversible capacities as well as improved rate performance.

Vibration Feature Extraction and Analysis of Industrial Ball Mill Using MEMS Accelerometer Sensor and Synchronized Data Analysis Technique

Abstract The use of advanced technologies such as Micro-electromechanical system (MEMS) sensors and low power wireless communication hold a great promise for optimal performance of industrial wet ball mill. The direct translation of the natural phenomena of the batch mill in a lab setup to a continuous process mill in the industry is quite perplexed in the nature of their intent and operating conditions. In this paper, the vibration signatures are analyzed for industrial wet ball mill using a MEMS accelerometer sensor. The signals are acquired using two wireless accelerometer sensors; mounted at feed and discharge end of the ball mill to validate the grinding status of the copper ore. The vibration spectrum before and after feed are compared to estimate the actual grinding status of the ore inside the mill. A limiting threshold level for the intensity is identified from the spectral analysis to monitor the desired grinding status of the ore. The high frequency (ZigBee) transmission loss due to diffraction is also compensated by the novel arrangement of the sensor transceiver. Finally, Pearson correlation technique is used to analyze the effect of sample length and its dependency with the rpm of the mill in determining the actual vibration signature.

Use of the attainable region method to simulate a full-scale ball mill with a realistic transport model

Optimisation and better control of milling circuits require extensive modelling of milling data. This paper extends the enquiry to the use of the attainable region (AR) technique to determine the optimal residence time of ore in a ball mill. It also evaluates the energy requirements of the mill at the set residence time to maximise the production of the desired size range which enables maximum recovery of platinum group minerals (PGM) during the flotation stage.With these purposes in mind, the breakage function and the scaled-up selection function parameters were used to simulate the operating conditions required by an industrial ball mill and the power requirements were predicted using the Morrell power model. This allowed the application of the AR methodology to be extended to a full-scale ball mill. Then a link was established between residence time to mill product specifications for a given feed size.The findings showed that the residence time required by a full-scale mill falls between those at which the fully mixed and the plug flow mills operate. The results also showed that operating the ball mill at a lower mill speed and a higher ball filling saves energy. Mill speed was again found to be a key operational factor for controlling the retention time of particles inside the mill. This yielded valuable insight for the importance of optimally controlling both the residence time of the material inside the mill and the amount of energy required to maximise the desired size range, in this case −75+9μm.