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The use of dry methods of processing and beneficiation of mineral raw materials is one of the promising areas, as this approach to concentrate production is less energy-consuming, less labor-intensive, and economically beneficial. The paper presents experimental studies on preliminary dry separation of Arkachan deposit ores to determine the quality of beneficiation of the separation products. The studies on dressability were carried out on pilot plants for dry ore processing and beneficiation: combined impact crusher DKD-300, centrifugal mill TsMVU-800, pneumatic separator POS-2000. Processing of the obtained separation products by pneumatic separation and screening according to the sequential flow chart of crushing and grinding was carried out in laboratory conditions at a gravity concentration table SKO-0.5. The GRG test was performed at an ITOMAK-0.1 centrifugal concentrator using a sequential grinding circuit. The GRG test showed that for more efficient gravity separation of gold, up to total gold recovery of 73.91%, the degree of grinding up to 80% passing 0.071 mm was required, allowing obtaining a gravity concentrate graded at 70.28 g/t gold.

The article presents the results of research on the development of processes and equipment for ore preparation and pneumatic dry beneficiation of mineral ores. The methods of crushing and grinding before enrichment of minerals have been considered, dry enrichment of geomaterials is investigated. Highly efficient prototypes of beneficiation equipment are developed and tested: crushers of multiple dynamic impact RD-MDV-900, DKD-300, centrifugal grinders CMVU-800 and VCI-12, pneumatic separator POS-2000. Fundamental designs are created, and a number of new ore preparation and pneumatic beneficiation instruments are being designed. The efficiency of approbation of an autonomous dry beneficiation complex with new safe environmental standards for the processing of gold-bearing ores, which makes it possible to fully release and extract free gold with a particle size from 10,000 to 100 µm, is shown. The introduction of the dry beneficiation method is very promising for the mining industry. It will allow to reduce capital costs for the construction of stationary beneficiation plants, completely or partially withdraw from the use of process water, the construction of a water supply system, a traditional tailing dam, etc.

The article presents a study of the influence of methods for calculating particle trajectories in the pneumatic separation channel (PSC) on the design parameters of the separation chamber (length and height of the exit window), completed in 2013-2021. The field of air flow velocities and trajectories of spring wheat seed material components in the separation chamber of fractioning pneumatic seed separator was constructed. The initial data for the calculation were the information obtained earlier when calculating the trajectories of particles in the PSC by various methods. The location at the outlet of the channel, the value and direction of the particle velocity vectors were determined by computer modelling using the Solidworks Flow Simulation software package and two experimental and theoretical methods. They took into account the real velocity field of the air flow with and without grain load. The obtained values of the design parameters are compared with the results of experimental studies of the separation chamber. It should be noted that the methods of calculating the trajectories of grain impurity particles have a significant impact on the length of the separation chamber and the height of the exit window. The maximum length of the separation chamber of 0.75 m will be required for computer modelling of the velocity field in the PSC. Much smaller values of 0.50 m and 0.45 m will be required when calculating the trajectories of particles in the PSC using the velocity field obtained by experimental and theoretical methods. During the experimental study of the separation chamber during the cleaning of wheat seeds, the optimal length of the separation chamber was determined to be 0.55 m with an exit window height of 0.30 m. Thus, the values of the design parameters of the separation chamber obtained by experimental and theoretical methods are the closest to experimental data, which makes it possible to recommend them for use at the design stage of pneumatic separators.

The article presents the comparison testing of particle trajectories in the pneumatic separation channel (PSC) of the pneumatic seed separator SP-2F and its bend, calculated using computer simulation method and two experimental-theoretical methods. They are based on taking into account the real airflow velocity field. In the first variant, the velocity field was measured in an idle mode, in the second at the nominal grain load. The studies were carried out in a vertical PSC with a supporting grid divided into two parts by a partition wall. In the variant with the theoretical velocity field the trajectories of light and grain impurities in the first part of the PSC are shifted closer to the outer wall. In the second part of the channel, particles with hovering speed of 8.0...10.0 m/s are carried upwards, and with hovering speed of 11.0 m/s they fall down into the purified material. In the variant of the experiment in an idle mode, particles with the hovering speed of 7.0...10.0 m/s rise up in the second part of the PSC. In the variant with grain load, particles with the hovering speed of 7.0...9.0 m/s rise upward and ricochet off the inner walls of the PSC and a bend wall, and particles with the hovering speed of more than 10.0 m/s fall down into the purified material. In the variant of the experiment with the grain load, the particle velocity with the hovering speed of 5.0...9.0 m/s at the exit of the PSC bend is more evened as compared to other options - 2.3...2.7 m/s, and the velocity vector of most particles is directed at a lower angle to the horizontal: from 4 up from the horizontal to 17 down from the horizontal. The most accurate is the calculation of particle trajectories using the velocity field in the PSC at the nominal grain load. The results of the study can be useful in the theoretical substantiation of the design parameters of pneumatic systems of grain cleaning machines.

To improve the separation efficiency of green leaf thresher, a pneumatic separator with heavier tobacco bypass was designed, meantime, the processing flow of the first stage pneumatic separating was modified accordingly. A mechanical roller is used to project tobacco, a deflector plate is used to adjust the projecting angle and distance, thereby to increase heavier tobacco output and deliver it directly to the second stage thresh, and to separate lighter tobacco from heavier tobacco precisely. The new separator was tested with tobacco of grade WCC3F in Tongren Redrying Factory of Guizhou Tobacco Redrying Limited Corporation, and the results showed that: 1) Compared with traditional pneumatic separator, the separation efficiency of the newly designed separator raised by 6.57 percentage points, the proportion of bypassed heavier tobacco reached 45%, the stem content in strips was less than 0.65%. 2) The moisture content and temperature of the heavier tobacco that went into the second stage thresher raised by 1.5 percentage points and 7.3 °C respectively, the large and medium-sized strip percentage increased by 0.69 percentage points, the breakage rate of strips was less than 0.25%, and the stem content in strips reduced by 0.23 percentage points. This technology provides a support for promoting the production performance of threshing lines. [ABSTRACT FROM AUTHOR]

In preparing of seed material it is important not only to compliance with the requirements of GOST R 52325-2005 for seed quality, content of seeds of other species, impurities, germination, but also the selection adjusted, the most biologically high-grade fractions. The use of airflow is one of the most common and effective ways to clean seeds from impurities. Separation of seeds by airflow allows to allocate the seeds with higher germination ability compared to separation on sieves. In Federal State Budgetary Scientific Institution "NIISH Severo-Vostoka" the effect of separation seeds of naked oat by airflow on yield quality and crop capacity was studied. Seeds were separated into heavy, medium and light fractions in two passes by the separator SP-4U-P. Grain yield in average in 2008-2010 at sowing seeds of light fraction was lower than control by 0.1-0.2 t/ha. When sowing seeds of heavy and medium fractions grain yield increased compared to control near equal - by 0.2-0.3 t/ha. Thus it is noted good sprouts, and tillering plants three days earlier. In order to reduce the discounted costs of cleaning the seeds pneumatic separator SP-2F was developed which one devides seeds on I-st and II-nd grade, grain forage and waste in a single pass. Evaluation of the quality of work of the separator carried at cleaning of covered oat Sapsan with base values: content of seeds of the main crop 97.04%, crushed grain 0.15%, husked grains 0.18%, small and feeble grain 2.47%, seeds of other species 6 pcs./kg, 1000 seeds weight 41.28 g. After pneumo-separation purity and germination of the I-st grade seeds rose to values met category OS, II grade - up to category РС with acceptable losses in the waste. Isolation of heavy and medium seed fractions with use of pneumatic separators increases yield quality and crop capacity. Application of pneumatic separator SP-2F allows to get the I and II grade seeds in one pass, and reduce the discounted costs.

Universal pneumatic separator of seed CP-2F is created for final cleaning and separaiting of seeds from impurities, differing by aerodynamic properties. Pneumatic separator contains the frame, diametrical fan, channel with support grid and partition wall, separation and sediment chambers, inertial jalousie-backward dust collector, input device of raw material of active type, output device for material, device of adjust the supply of material and the air flow rate, drive mechanisms of working bodies. Acceptance tests were carried out on the secondary cleaning of seeds of spring oats and red clover at filing 1.02.1.75 and 0.46.0.78 t/hour respectively. The purity of the inputing material of oats was 96.17.96.8%. The bulk of the waste it taken by squashed oat grains - 2.36.3.38% and crushed grain - 0.22.0.76%. The purity of the clover inputing material ranged from 95.94 to 96.58%. The waste consisted with seeds of timothy grass and meadow fescue 3.42.4.06%. The predominant species of weed were creeping thistle and meadow fescue. After cleaning first grade seeds of oats have purity about 97.60.98.81%, this is below requirements of the Terms of Reference (99.0%). The cleaning efficiency meet regulatory (no less 80%), with performance up to 1.20 t/h. Low purity of oats seeds caused by presence of squashed grain and crushed grain in inputing material. Clover seeds of first grade at all modes correspond purity categories of elite seeds with cleaning efficiency 85.8.96.4%. Seed losses in waste at cleaning of both crops do not exceed the allowance. Seed crushing is not found. According to the results of acceptance tests separator of seed CP-2F is recommended for use in agriculture.