Drum Rotation Research Articles

Prediction of barite recovery and grade by multiple linear regression (MLR) analysis in concentrating of barite tailings by using multi-gravity separator (MGS)

Multi-gravity separator (MGS) is a very effective separator for very fine-sized minerals. In this study, for the first time in the literature, the concentrability of a typical barite plant fines (tailing) was investigated by using an MGS. For this purpose, the effects of different operating parameters such as the solids ratio of feed pulp, the rotational drum speed, the wash water flow rate, and the tilt angle were studied in detail. Additionally, multiple linear regression (MLR) analyses were performed to understand the effect of operating parameters on the separator (MGS) performance for barite tailings, and the equations were developed to predict the recovery and the grade of barite concentrate fraction. As a result of experiments, a barite concentrate from the barite tailing containing 38.40% BaSO4 was obtained with 92.55% BaSO4 grade and a total barite recovery of 78.41%. MLR studies also showed that there were good correlations between the experimental results and predicted values (R 2 values of 0.928 and 0.853 for the recovery and grade of barite concentrate, respectively). Based on the results obtained from this study, it can be concluded that while the solids ratio of feed pulp showed an important effect on the BaSO4 grade, the tilt angle had an effect on the recovery of the barite concentrate.

THE DRUM ROTATION VELOCITY VALUE WHEN AUTO-OSCILLATION SELF-EXCITATION WITH MAXIMUM SWING OF A POLYGRANULAR INTRACHAMBER FILL

The influences of the structure of two-fractional polygranular intrachamber fill on the drum rotation velocity value when auto-oscillation self-excitation with maximum swing is considered. The pulsating mode of flow of such intrachamber fill is used in the self-oscillating grinding process in a tumbling mill. Spherical particles of non-coherent granular material of 2.2 mm size were used as a large fraction modeling the grinding bodies. Cement was used as the small fraction modeling the particles of the crushed material. The factors of experimental studies were accepted: the gaps between particles of large fraction degree of filling at rest dispersed particles of small fraction 0, 25, 50 and 100%, the relative size of particles of large fraction in the drum chamber 0.519, 0.733, 1.04, 1.47, 2.08, 2.93, 4.15 and 5.87% (drum chamber radius 212, 150, 106, 75, 53, 37.5, 26.5 and 18.75 mm), the chamber degree of filling at rest 25, 35 and 45%. The method of visual analysis of transient processes of self-oscillating fill flow modes in the cross section of a rotating chamber was applied. Measurements of the drum rotation velocity during fill self-excited self-oscillations were performed. The magnitude of the self-oscillation swing was estimated by the increase in the difference of the maximum and minimum values of the fill dilatation over one period of pulsating. The magnitude of the relative drum rotation velocity at the maximum range of fill self-oscillation swing varied within 0.777-1.4. The effect of a decrease in the relative drum rotation velocity value, when the maximum polygranular intrachamber fill self-oscillations swing, with enhanced fill coherent properties has been registered. A decrease in the relative rotational velocity was established with a decrease in the relative particle size of large fill fraction and an increase in the content of small fill fraction and an increase in the chamber degree of filling. A sharp intensification of the decrease in the relative rotation velocity at a value of the relative size of large particles of less than 0.015 is revealed.

Validating N-body code chrono for granular DEM simulations in reduced-gravity environments

ABSTRACT The Discrete Element Method (DEM) is frequently used to model complex granular systems and to augment the knowledge that we obtain through theory, experimentation, and real-world observations. Numerical simulations are a particularly powerful tool for studying the regolith-covered surfaces of asteroids, comets, and small moons, where reduced-gravity environments produce ill-defined flow behaviours. In this work, we present a method for validating soft-sphere DEM codes for both terrestrial and small-body granular environments. The open-source code chrono is modified and evaluated first with a series of simple two-body-collision tests, and then, with a set of piling and tumbler tests. In the piling tests, we vary the coefficient of rolling friction to calibrate the simulations against experiments with 1 mm glass beads. Then, we use the friction coefficient to model the flow of 1 mm glass beads in a rotating drum, using a drum configuration from a previous experimental study. We measure the dynamic angle of repose, the flowing layer thickness, and the flowing layer velocity for tests with different particle sizes, contact force models, coefficients of rolling friction, cohesion levels, drum rotation speeds, and gravity levels. The tests show that the same flow patterns can be observed at the Earth and reduced-gravity levels if the drum rotation speed and the gravity level are set according to the dimensionless parameter known as the Froude number. chrono is successfully validated against known flow behaviours at different gravity and cohesion levels, and will be used to study small-body regolith dynamics in future works.

On the determination of design and geometric parameters of a upper bit slurry grinder

Experimental and field studies have identified the rational geometric dimensions of elements of upper bit sludge grinder, ensuring its operation’s stability. Laboratory studies of upper bit device model showed that the amplitude of drum oscillations depends on the shaft rotation frequency, spring stiffness, and drum inertia moment. To determine the dimensions of working channels and drum openings of a upper bit device, the analysis of slurry samples from directional and horizontal wells was carried out. Designs of a slurry grinder for drilling wells with cone bits with diameters of 146 and 215.9 mm have been developed. Field tests showed that the use of the developed design of near-bit sludge grinder allows to increase the mechanical speed by 18% compared to the conventional method of drilling.

Increasing the biological activity of benzimidazoles based on the supramolecular nanoscale delivery system with licorice extract against helminthiasis

This paper considers the effect of mechanochemical technology on the anthelmintic efficacy of a solid dispersion (SD) of albendazole (ABZ) with licorice extract (LE) / SDALE/, which is considered as a means of targeted delivery. SDALE tests were carried out on white mice experimentally infected with Trichinella spiralis and Hymenolepis nana and on sheep naturally infected with gastrointestinal strongylates and Moniezia expansa cestodes. For each helminthiasis, animals of different groups of 9–12 in each were orally administered once a dose of SDALE of 2.0 mg/kg of active substance (AS) in the form of 10–20 % powders and 1 and 2% suspensions in comparison with the basic drug - a substance of albendazole at the dose of 2.0 mg/kg. SDALE is prepared by joint milling of similar components (ABZ and LE) in grinders with adjustable immersion energy (module, time, weight ratio of components, drum rotation speed) for 2 hours. Animals of the control groups did not receive the drug. The activity of the drugs was determined according to the data of coproovoscopic examination of sheep by flotation method before and 15 days after treatment. SDALE at the dose of 2.0 mg/kg of AS in the form of 10 and 20% powders and 1 and 2% suspensions showed respectively 91.4; 89.3; 87.2 and 92.3% efficacy against Nematodirus spp. and 90.7; 88.4; 87.4 and 91.2% activity against other types of Strongylata when receiving a 23.2 and 22.7% effect of the base drug - ABZ.

Biofermentation of organic waste from a pig-breeding complex in a drum-type installa-tion

Relevance. In modern pig-breeding complexes, manure is processed by separation producing the liquid and solid manure fractions. The complexes also generate other types of organic waste. Testing the process of producing the organic fertilizer based on the solid organic waste of a pig-breeding complex in a drum-type biofermenter.Material and methods. The processing of a mixture of two types of solid fractions of pig slurry and the waste from mechanical cleaning of grain into an organic fertilizer in a drum-type biofermentation unit was tested. The tested material was produced on the pig-breeding complex with the closed production cycle located in Leningrad Region. The optimization criterion was the temperature of the mixture in the installation. The controlling factors were the aeration frequency, the air supply rate to the biofermenter, and the rotation interval of the drum. Assumed values of the tested factors were: the moisture content of the mixture of 55–65% and the density of the mixture of 400– 600 kg/m3. The standard methods for statistical and experimental data analysis were applied.Results. Four operation modes of the biofermenter were tested, of which only one allowed to achieve the heating of the mixture above 55 °C and a stable course of the biofermentation process. Under this mode, the aeration rate was 5 min/h; the air supply rate to the biofermenter was 10 m/s; and the drum rotation interval was every 12 hours. The significance of the factors in a multivariate experiment was considered; the mathematical model was analyzed using the steepest ascent method. Considering the identified operation mode, 12 drum-type biofermenters with the working volume of 31.3 m3 each will be needed to process the solid fraction of manure produced on the pig-breeding complex with the animal stock of 107,000 head and the output of the solid fraction of manure of 90 tons per day. A building with a floor area of 1000 m2 will be required to place these biofermenters. This area is 113.4 times smaller than the area of the watertight pad for clamps to process the manure by the passive composting technology. Nitrogen emissions will be reduced by 6.3% owing to the intense mineralization of nitrogen in the fermented mixture.

Cutting length the fodders of green stalks by drum chopper

In Uzbekistan, special attention is paid to the development of livestock, poultry, and fish farming. In the ration of animals, green fodder obtained by cutting green stalks corn, alfalfa and other feed crops have a special place. For high-quality chopping of stalks with the required cutting length for each type of animal, a chopper has been developed with a simple design for chopping green feed. Testing of the chopper work, carried out at an engine speed of 2800 rpm, a cutting drum rotation speed of 950 rpm and in two rotations of the feed rollers 10 rpm and 20 rpm with an average length of alfalfa stalks 71.6 cm and an average length of corn stalks 216.4 cm, showed that at a feed roller rotation speed of 10 rpm the average cutting length of the stalks was 10.6 mm, and at a feed roller rotation speed of 20 rpm - 17.6 mm. It can be seen from the data that with a twice increase in the feed roll speed, the cutting length increases 1.66 times, which confirms the theoretical assumptions obtained.

Investigation of the Quality of the Mixture at the First Stage of Operation of a Gravitational Apparatus

The quality of the mixture obtained after the first stage of batch mixing of loose components in the preparation of a finished mixture with a ratio of 1:10 or more is assessed, according to the proposed method of three stages and the results of stochastic simulation of the process of mixing of loose materials in a gravitational apparatus during operation of drums with screw-wound brush elements installed above the trays and with inclined bumpers. The models of the formation of rarefied torches of two types of particles in two cases were employed: (1) after the interaction with the brush elements of the layers of dosage components coming from the drum–tray gap and (2) after the impact of the incoming torches on the bumper. For the first stage of mixing, dependences of the volume and weight fraction of the key component on the reflection angles are simulated with allowance for the physical mechanical properties of the materials and the design and regime parameters of the apparatus, based on the corresponding nonequilibrium differential distribution functions for the number of particles of each component in the angle of scattering from the brush elements (case 1) and the angle of reflection from the bumpers surface (case 2). Using the proposed recurrence relation for dosage materials, the coefficient of inhomogeneity of the mixture at the first stage of mixing particulate components is calculated with the focus on the most significant factors of a quality mixing: the angular speed of drum rotation ω; the degree of deformation of brush elements Δ (the ratio of their length to the height of the drum–tray gap); and the angle of inclination of bumpers to the horizon ψ1. Analysis of the theoretical and experimental results showed their satisfactory agreement and made it possible to reveal the most rational ranges of variation of the сhosen process parameters at the first mixing stage: ω = (45.5–47.2) s–1; Δ = (1.48–1.52); and ψ1 = (0.87–1.04) rad. These findings can be used in the development of the engineering methodology for calculating new gravity mixers.

Scaling behavior of particle breakage in granular flows inside rotating drums.

We perform systematic particle dynamics simulations of granular flows composed of breakable particles in a 2D rotating drum to investigate the evolution of the mean particle size and specific surface as a function of system parameters such as drum size, rotation speed, filling degree, and particle shape and size. The specific surface increases at a nearly constant rate up to a point where particle breakage begins to slow down. The rates of particle breakage for all values of system parameters are found to collapse on a master curve when the times are scaled by the characteristic time defined in the linear regime. We determine the characteristic time as a function of all system parameters, and we show that the rate of particle breakage can be expressed as a linear function of a general scaling parameter that incorporates all our system parameters. This scaling behavior provides a general framework for the upscaling of drum grinding process from laboratory to industrial scale.

Impacts of hybrid (convective‐infrared‐rotary drum) drying on the quality attributes of green pea

AbstractA hybrid convective‐infrared‐rotary drum (CIRD) dryer was designed and fabricated to examine the drying behavior of the green pea under different experimental conditions. In this study, the effect of temperature was evaluated at three levels (40, 55, and 70°C); while the infrared (IR) power and drum rotation speed were also varied in three levels: 250, 500, and 750 W and 5, 10, and 15 rpm, respectively. The effect of these three variables was assessed on the drying, durability extension and quality of the green peas. Drying of green pea with CIRD method by the following conditions: air temperature, IR power and drum rotation speed enhanced the drying rate, the variations in the effective moisture diffusion coefficient, rehydration ratio, total phenol content, and antioxidant capacity. In addition, increasing temperature, IR power, and rotary speed reduce the color changes and specific energy consumption. The highest effective moisture diffusion coefficient, rehydration ratio, total phenol content, and antioxidant capacity were 1.58 × 10−11 m2/s, 2.19 ± 0.13, 12.99 ± 0.35 mg GAE/g dry sample, and 75.73 ± 0.82%, respectively. Moreover, the lowest specific energy consumption, color variation, and pH were 107.49 ± 0.88 MJ/kg, 44.40 ± 0.51, and 4.98 ± 0.11, respectively. The highest qualitative and nutritional preservation belonged to the highest air temperature, maximum IR power, and highest drum speed.Practical applicationsToday, drying is not only a way to store foodstuffs, but it is also known as a way to increase the value added to food products. Extracting water from a product under controlled conditions reduces the moisture of foods to a certain level and prevents microbial growth that causes foods to spoil. One of the main goals of modern food technology is to maximize nutrient protection during the process and storage. In addition, antioxidant compounds reduce the risk of developing a variety of cancers and cardiovascular disease by eliminating free radicals and active oxygen.

Research of loading of loose components the lock feeder at secondary temporary dispensing for non-mixing automatic machines

Results of pilot study and their statistical processing on the basis of multiple-factor experiment are provided. Operation of the stand of the lock feeder applied to dispensing of bulks from metal powders by way of time separation from the flow of micro doses of components given by the feeder was investigated. These feeders are used as the automation equipment in conveyor, rotor and birotary non-mixing installations. Regression models for determination of the actual productivity of lock feeder are received. It is established that dependences of productivity of lock feeders on the circumferential speed of rotation of the dosing drum and its operating volume are nonlinear. At the constant volume of grooves, the same productivity can be received at different values, the circumferential speed of drum that is at implementation of the different kinematic modes. At design and the choice of processing equipment it is necessary to use the received dependences that will allow on the set actual capacity of the feeder to choose geometry and kinematic parameters of process of dispensing.

Improving the efficiency of tilling the soil for combine harvesting potatoes

The article deals with the problem of reducing the content of clods in the soil, in order to prepare it for combine harvesting potatoes. To do this, we proposed a soil-tilling rotary plow with a serrated knife shape. Tillage machines with active working bodies provide high quality tillage before planting, creating the conditions for the efficient cultivation of potatoes. The article also presents the results of a study of the influence of the cutter knife length, the milling drum rotation speed and the number of knives on the amount of the soil crumbling. The research program is presented, as well as the levels and intervals of factors variation are presented. Based on the research results, the regression equation was obtained and analyzed, which reflects in a coded form the influence of significant factors on the degree of soil crumbling. Theoretical background was verified by fi eld studies of the proposed rotary plow with a serrated knife profi le on the fi elds of Belaya Dacha Farming LLC, Tambov District, Tambov Region. Testing of a soil-tilling rotary plow with a serrated profi le of knives was carried out during the soil loosening after harvesting barley. Soil moisture content was 17.3–20.9 %, hardness was 0.8–1.8 MPa, soil density was 0.9–1.0 g/cm3 . The average height of plant and crop residues was 20 cm. From the results of the agrotechnical appraisal, it is clear that when processing the depth of 11.6 cm, the quality of crumbling was satisfactory, the density of the cultivation layer was 1.10 g/cm3 , which meets the agrotechnical requirements for the maturation of potatoes. Weed plants are pruned completely. The height of the ridges was 1.54–1.62 cm. In heavy soils, the combines began to work easier, the heap became clean from clods and damage to tubers was reduced. When combineharvesting potatoes, their productivity in the prepared area by rotatilling increased by almost 25 %. The amount of soil impurities in the hopper decreases by 35–40 %.

An experimental investigation on fracture parameters of recycled aggregate concrete with optimized ball milling method

In this paper, Ball Milling Method (BMM) is employed on recycled aggregate (RA) with an optimization process which is conducted to enhance RA efficiently eliminating attached old mortar (AOM) content in RA. Various combinations of drum rotation (R) (100-200-300-400-500) and the steel balls (S) (0-2-5-7-10-12) applied to the recycled aggregate during the BMM process and treated recycled aggregates (RAi) are obtained. The mechanical properties (compressive, splitting tensile and flexural strength values and elasticity modulus) and the non-linear fracture parameters (effective crack length, crack mouth opening displacement, crack tip opening displacement, initial cracking toughness, unstable fracture toughness and fracture energy) of concretes including untreated and treated recycled aggregate (RAi) are determined. The test results proved that the water absorption values of recycled aggregates in the size of 4–11.2 mm and 11.2–22.4 mm reduced from 8.80% to 1.40% and 8.95% to 0.84%, respectively, after treatment process. It is also found that the compressive strength of concretes are marginally affected with the use of treated recycled aggregate (RAi) up to 60% which is twofold of the optimum recycled aggregate proportion given in the literature. Moreover, 60% RAi content in concrete can be recommended in terms of fracture characteristics (ac, CMODc, CTODc, Kıcini, Kıcun and GF).

Heat transfer enhancement in rotary drum dryer by incorporating jet impingement to accelerate drying rate

The purpose of this study was to investigate experimentally the effects of impinging jets installed in a conventional rotary dryer for heat transfer enhancement. The metal drum had as insert a jet tunnel at the centerline, and the jets were arranged in an in-line configuration on the jet tunnel. A jet-to-jet (S) and a jet-to-target (H) distances were fixed at S/d = 6 and H/d = 4, respectively. Jet velocity (Vj ) was set at Vj = 5, 10 and 15 m/s, while jet temperature (Tj ) was 70, 80 or 90 °C. Drum rotation speed (N) was also investigated at N = 0.5, 1, and 3 rpm. The conventional rotary dryer was examined at the same mass flow rate of hot air to compare with the case having impinging jets. All experiments were conducted by batch drying 5 kg of fresh chilies for 8 hours. Results showed that installing jets gave more effective heat transfer, which accelerated water removal over that with the conventional rotary dryer, and the moisture contents were greatly reduced. On using impinging jets, the jet temperature had more influence on heat transfer enhancement than the jet velocity. In comparison, the effect of drum speed was small.

Analysis of Statistics on Methane Release in High-Production Coal Faces in Kuzbass

The statistical analysis results on methane release in coal faces in Kuzbass are presented. The parabolic curves of methane release have maximums as regard to feed velocity and productivity of shearer. Methane release from broken coal is an inverse proportional function of linear hyperbolic dependence and has maximum as regard to feed velocity and productivity of shearer. The analysis of the found methane release from broken coal shows that methane release reduces as a quadratic dependence with decreasing drum rotation speed and number of picks per cutting line, and increases also as a quadratic dependence with growing thickness of coal seam and shearer web width.

Distribution of the components of the building mixture in the presence of secondary raw materials during rotary mixing

The purpose of this study is a stochastic description of the distribution of solid dispersed components, including those from secondary raw materials, according to the characteristic angle of scattering ϴij when receiving a construction mixture at the first stage of operation of the rotary apparatus. Two stages of the formation of rarefied flows are assumed: when scattering particles of components by elastic blades of a rotating drum and when interacting with the baffle surface. Modeling method this is energy method of Klimontovich Yu.L. The analysis of the efficiency of the first stage (rotary mixing) is carried out based on the obtained distribution functions of the number of particles of bulk components over the scattering angle, taking into account their physical and mechanical properties and a variety of design and operating parameters of the apparatus. The bulk of the particles of the mixed components are scattered at the initial angles of rotation of the mixing drum, when the deformation of the elastic blades is most significant. This is accompanied by the characteristic first bursts of the obtained distribution curves (ϴij< 0.1 rad) for the number of particles of the tested bulk materials at the given ranges of parameters.

Manipulating Chain Type and Flail Drum Speed for Better Fibre Recovery in Chain-Flail Delimber-Debarker-Chipper Operations

A chain-flail delimber-debarker-chipper (CFDDC) was adapted for treating smaller trees than normal by replacing the standard flails with lighter ones, and by reducing flail drum rotation speed. The machine produced 16 full containers (24 t each) for the standard configuration and 24 full containers for the innovative one. For each container the researchers measured: original tree mass, chip mass, time consumption and fuel use. Results indicated that the innovative setting accrued a 12% improvement on fiber recovery compared with the standard setting (control). At the same time, productivity increased by 20% and fuel consumption was reduced by 30%. Product quality was largely unaffected, with bark content remaining below the 1% threshold specification. If at all, product quality was improved through the reduction of fine particles, possibly derived from less diffused fraying. These results have triggered the real scale adoption of the new setting by contractors who participated in the study. The success of the innovative treatment is likely explained by its better alignment with the weaker structure of small trees from low-yielding stands.

Numerical research on wear characteristics of drum based on discrete element method (DEM)

Drum works on high impact and non-linear load condition, which easily results in wear and failure. However, it is still an urgent problem to study the wear mechanism of drum and how to reduce the drum wear. In this study, the coupling model of drum cutting in complex coal seam was established using discrete element method (DEM). Then, the motion state of coal/rock particles, the wear distribution of drum and the influence of working parameters on drum wear were all studied to reveal the wear mechanism. To reduce the wear of drum and take into account the cutting performance of shearer, the optimal working parameters were obtained based on the multi-objective optimization theory. The results indicate that abrasive wear is the main form of drum wear. Wear of pick and blade among the drum assembly is relatively serious. The main influencing parameter of pick wear is traction speed and that of blade wear is drum rotation speed. Under the certain working condition, when the traction speed is 4.85 m/min, the drum rotation speed is 86.82 r/min, and the spiral angle is 13.8°, the wear of drum will be reduced to a certain extent, and the comprehensive performance of the shearer will be optimal.

Implementation of an automatic control system on a roaster of peruvian andes grains

This paper presents the results of the automation of a roaster of grains grown in the Peruvian Andes. The research work consisted in developing an automatic control system for the temperature and speed of rotation of the drum of a gas roaster machine with mechanical-electrical control. The new system is based on a PLC with a proportional control algorithm for temperature and an open loop for drum rotation, which allows the grain temperature to develop, in time, the predefined curves for its 3 types: corn, broad beans and soybeans. The cultivation of these in the various microclimates along the Andes Mountains gives them unique characteristics that condition the proper roasting to the operator’s experience. To that end, a matrix was developed with parameters whose values were determined by tests conducted by expert operators in manual roasting. The experimental results showed that the roasted beans reached the desired quality characteristics such as humidity, color, aroma and flavor, as well as a decrease in the duration of the process and in fuel consumption, as well as the reduction of waste for over-roasting.

Coupled CFD-DEM Simulation of Tea Particles in a Cylinder Fixation Equipment

This paper presents a coupled CFD-DEM approach to simulate the process of tea fixation in a cylinder fixation equipment. We have carried out quantitative assessments of process conditions, such as rotation speed, number and height of lifter and drum tilt. The temperature and movement charatertristic of particles in the drum are obtained and analyzed. We assess the performance of our framework by employing temperature rising rate, which presents the efficiency of heat transfer between hot air and particles. An orthogonal experiment with four factors and three levels was designed, and the results show that the rotation speed and drum tilt have great influence on the temperature rising rate of tea particles, and the number and the height of lifter had little influence on the temperature rising rate. Finally, we have identified a lifter of 14 pieces and 70 cm height, a rotation speed of 20 r/min and a drum tilt of 3 degrees as a set of optimal operating conditions.