Substantiation of technological resource-saving conditions for the use of equipment in the sand deposit mining

The mining and technological features of the Gusarovsky deposit of molding sands mining under the conditions of technological limitations of the existing enterprise have been studied. The granulometric composition of balance reserve sands, as well as overburden rocks, was analyzed. In order to obtain a high-quality commercial product with a minimum content of fine and clay particles from the initial rock mass of the surface and watered ledges, the parameters of the hydromechanized complex were substantiated by mining and processing. The calculation is based on the three most available options for filling the mining and processing complex (MPC). To substantiate the rational parameters of the MPC and ensure the purification of the commercial product from fine impurities, a graphical characteristic of the hydraulic vertical classifier GKCD2000 was constructed when supplying clean water and at a slurry concentration of 10%. The graphical characteristics of hydraulic transport systems were constructed in accordance with the design diagrams of the accepted variants of the complex. To substantiate the rational parameters of the pumping station, the characteristics of the mining and processing complex were constructed when pumping clean water and slurry at a concentration of 10%. For the first time, the rational parameters of the technological complex of mining and processing, consisting of a suction dredger – a transport slurry pipeline – and a vertical hydraulic classifier GKCD2000, have been substantiated. The development of a technological complex of mining and processing will allow the existing enterprise to continue developing the deposit and obtaining high-quality commercial products under the conditions of technological limitations.


Introduction
Gusarovsky mining and processing plant (MPP) for molding materials is located near the Gusarovka village in the Kharkov region [1].Since the middle of the last century, the enterprise has been developing the Gusarovsky deposit of molding sands [2].The mineral consists of molding sands and is developed by two mining ledges, above-water and underwater, which is due to the peculiarities of the geological structure of the deposit and the hydrogeological conditions of occurrence [3].To develop the deposit, traditional technological schemes are used with excavator development of surface mining and overburden benches [4].The underwater ledge is developed using a floating suction dredger, followed In terms of grain and chemical composition [7], and physical and mechanical properties [8], the sands of the watered ledge correspond to the quartz group of molding sands [9] (GOST 2138-91.Molding sands.General technical conditions).The sands of the above-water ledge in their chemical composition and physical and mechanical properties correspond to the quartz group of molding sands [10]; however, due to the presence of more than 2% clay component, they are classified as a lean group [11].After hydraulic processing, the sands of the above-water bench can claim to correspond to the quartz group of molding sands [12].
The granulometric composition of the sands from the overburden rocks which belong to the Gusarovsky molding sand deposit was studied by specialists from the Planning and Design Office Hydraulic Technology of Mining (htmp.com.ua).Single samples of sand from four overburden ledges were examined [13].Based on the results of the work performed, the sands of the 1 st and 2 nd overburden ledges are of greatest interest.The study of samples [14] showed that, according to the size class of 0.1-0.16mm, the specific exit made up respectively overburden ledges: 1 -86.8 %; 2 -51.5%.At the same time, the yield for dusty and fine particles was less than 0.05 mm, respectively, for the overburden ledges: 1 -5.4 %; 2 -6.1%.Such values of the granulometric composition show that after gravitational hydraulic processing, in terms of grain composition, these sands can claim to correspond to the lean or quartz group of molding sands [15] (GOST 2138-91.Molding sands.General technical conditions).
A preliminary study of physical and mechanical characteristics of the sand mining surface ledge [16], as well as sand intermediate overburden ledges [17], shows that in terms of granulometric composition, this granular material category may be processed to obtain additional significant volumes of commodity products that comply with current standards for foundry sands [18].Therefore, the rational parameters of the complex for mining and processing substandard sands in the conditions of Gusarovsky MPP is an important and relevant scientific and technical task.

Methods
The research was accompanied by the use of certain well-known technological and design solutions for hydromechanized mining [19], transportation [20], processing [21], and storage of molding sands [22] with the formation of previously unknown sequences and connections as part of the technological complex of mining and processing in relation to the peculiarities of the geological structure of the deposit and the physical and mechanical properties of the mineral [23].The work used well-known techniques IOP Publishing doi:10.1088/1755-1315/1269/1/0120243 [24] to determine the parameters of the movement of solid particles within the flow part of a vertical hydraulic classifier [25].
The construction of graphical characteristics of hydraulic transport systems [26] in accordance with the design schemes of the accepted options for the mining and processing complex is carried out on the basis of known analytical dependencies [27], mathematical constants [28], and hydraulic characteristics [29].The volumetric concentration of slurry adopted in the hydraulic calculations of the complex elements is limited to 10% in accordance with the recommendations for hydraulic mechanization systems during the mining and transportation of soil.

Justification of the parameters of the hydromechanized complex of sand mining and processing based on the GKCD2000 classifier
Taking into account the recommendations of the Gusarovsky MPP's management, when developing technical solutions in order to minimize capital costs to saturate the complex, the equipment available at the enterprise was used to the maximum.These included the following units: a suction dredger with a 20R-11m soil pump, a Gr 1600-25 soil pump, and a vertical hydraulic classifier GKCD2000.
A general view of the vertical hydraulic classifier GKCD2000 in the form of a computer model developed in the specialized SolidWorks program is shown in Figure 1.
Taking into account such technological limitations, the work calculated the rational parameters of the mining and processing complex (MPC) based on a suction dredger, a transport slurry pipeline, and a vertical hydraulic classifier GKCD2000.The purpose of the performed justification of the complex parameters was the selection of equipment and its operating parameters to obtain a high-quality commercial product with a minimum content of fine and clay particles from the initial rock mass of the surface and watered ledges of the Gusarovskoye molding sands deposit.

Figure 1. SolidWorks model of hydraulic vertical classifier GKCD2000
The calculation is based on the three most accessible options for filling the MPC: 1a suction dredger with a 20R-11m soil pump, a slurry pipeline based on a straight-seam electric-welded steel pipe in accordance with GOST 10704-91 DN 630 mm, a hydraulic vertical classifier GKTSD2000 (Fig. 2).3a suction dredger with a Gr 1600-25 soil pump, a pumping station based on a Gr 1600-25 soil pump, a slurry pipeline based on a straight-seam electric-welded steel pipe in accordance with GOST 10704-91 DN 325 mm, a hydraulic vertical classifier GKCD2000 (Fig. 3).

Construction of characteristics of the hydraulic vertical classifier GKCD2000
For calculation, the following initial data were used for the technological and operating parameters of the mining and processing complex.
Mineral resources -molding sand, overburden sand.The granulometric composition of the feedstock is given in Table 1; Depth of mineral mining Hm -10 m; Geometric height of pulp lifting Hl -17 m; Residual pressure when releasing slurry from the classifier Ho -1 m; The transportation distance, for options 1 and 2 -Ltr (Fig. 2), for option 3 -L1 and L2 (Fig. 3)are determined by calculations; The annual operating period of the enterprise is 4160 hours.
To substantiate the rational parameters of the MPC and ensure purification of the commercial product from fine impurities, a graphical characteristic of the hydraulic vertical classifier GKCD2000 was constructed when supplying clean water and at a slurry concentration of 10% (Fig. 4).Axis X shows the hydraulic transport system productivity for pumping slurry Qs (m 3 /hr), and Axis Y shows the average sand size dav (mm).Calculations were performed using known analytical dependencies [30] and data on the rate of sedimentation of round solid particles in water [31].The chart corresponds to the value of the limiting particle size of solid particles.It is obvious that solid particles located above the chart will settle and represent a commercial product, solid particles from the area below the chart will be carried by the slurry flow outside the classifier and are sludge.The chart shows that an increase in the productivity of the slurry feeding the classification process will lead to an increase in the value of the limiting separation size.Taking into account the data on the granulometric composition of sand, to obtain a high-quality commercial product, a feeding area from 1000 to 1200 m 3 /hour is rational.

Construction of hydraulic transport system characteristics
Obtaining a commercial product purified from fine impurities can be ensured by substantiating the rational parameters of the MPC.Taking into account the known design and technological parameters specified in the initial data, the main changeable parameters are the following operating parameters of the compressor chamber: slurry productivity at the entrance to the classifier and the length of the slurry pipeline.In this section, the graphical characteristics of hydraulic transport systems are constructed in accordance with the design diagrams of MPC options 1-3 (Fig. 2, 3).Calculations were performed using known analytical dependencies [32].The calculations performed include the following necessary sections: 1conversion of the characteristics of the soil pump from water to slurry; 2calculation of the performance of the hydraulic transport system; 3justification of the parameters of the main slurry pipeline; 4construction of the flow-pressure characteristics of the transport slurry pipeline and the slurry pump; 5calculation of the power parameters of the drive of the soil pump.
Due to the cumbersomeness of the mathematical apparatus used for these calculations when constructing graphical characteristics, this work presents only the results obtained.
In accordance with the design diagram of the MPC 1, shown in Figure 2, calculations and construction of the flow-pressure characteristics of the MPC were carried out.Calculations were made for transportation ranges Ltr of 1000 and 500 m, which provide rational operating conditions for the control panel with the specified equipment.When operating under these conditions, the hydraulic transport system provides slurry productivity of 3750 and 5000 m 3 /hour, respectively.
The results of calculations and construction of the flow-pressure characteristics of the MPC in accordance with the design scheme 2 (Fig. 2) showed that with a transportation distance of Ltr 250 and 100 m, which provide rational operating conditions for the MPC with the specified equipment, the hydraulic transport system provides slurry productivity from 750 to 1000 m 3 /hour.
Calculations and construction of the flow-pressure characteristics of the pumping station were also carried out in accordance with design diagram 3, shown in Figure 3.The calculations were performed in two stages, since the hydraulic transport system consists of two sequentially installed soil pumps.So, with transportation distances L1= 340 and L2= 140 m, the hydraulic transport system provides a pulp productivity of 1000 m 3 /hour.With a minimum transportation distance of L1= 170 and L2= 50 m, the hydraulic transport system provides a slurry capacity of 1300 m 3 /hour.

Construction of the mining and processing complex characteristics
To substantiate the rational parameters of the MPC, the characteristics of the mining and processing complex were constructed using previously obtained calculation data.The results of the data obtained for pure water and a slurry concentration of 10% are shown in Figure 5.
From the characteristics it is clear that the use of the MPC in accordance with option 1 as part of a suction dredger with a 20R-11m soil pump, a DN 630 mm slurry pipeline, and a GKCD2000 classifier (Fig. 2) will lead to losses of the main amount of the commercial product.In this regard, this filling of the complex cannot be recommended for use in the conditions of the Gusarovsky MPP.
The use of the MPC in accordance with option 2 as part of a suction dredger with a Gr 1600-25 soil pump, a DN 325 mm slurry pipeline, and a GKCD2000 classifier with a minimum slurry transportation distance of about 100 m can be implemented.However, with such a length of the slurry pipeline, maneuvering the suction dredger can be difficult, and its use to develop the entire underwater ledge becomes impossible.Thus, this version of the MPC can be recommended for use only at the initial stage to assess the performance and test the technological and design parameters of the equipment.
It is clear from the characteristics (Fig. 5) that for high-quality cleaning of sand from fine and clay impurities, the mining system must provide sufficient productivity when supplying slurry to the classifier.In the conditions of the Gusarovsky MPP, one of the possible options for filling the hydromechanized sand mining and processing complex is a pumping station based on a suction dredger with a Gr 1600-25 soil pump, a Gr 1600-25 pumping station, a DN 325 mm slurry pipeline, and a GKCD2000 classifier (option 3, Fig. 3).To process sand from the surface mining bench, as well as sand from overburden benches mined by the dry method, a version of mining and processing complex 3 with preliminary preparation of the slurry and maximum use of the resources available to the enterprise can also be implemented.In this case, a feeder hopper for initial overburden sand, a belt conveyor and a slurry preparation hopper should be added to the technological complex proposed in the work.Such an upgrade of the complex will allow us to additionally process large volume of sand from overburden benches and perform their pre-process it, which will allow us to obtain marketable products of higher quality.Prospective studies of the technological acceptability and economic feasibility of using such a complex are planned for further research by a team of authors.

Conclusions
As a result of justification of technology and equipment parameters for the mining and processing of foundry sands in the conditions of the Gusarovsky MPP and minimal capital investments, the rationality of using a hydromechanized complex for the mining and processing of MPC based on a suction dredger with a soil pump Gr 1600-25, a slurry pipeline DN 325 mm long 170 m, pumping station Gr 1600-25, slurry pipeline DN 325 mm, length 50 m, vertical hydraulic classifier GKCD2000.The calculations and IOP Publishing doi:10.1088/1755-1315/1269/1/0120247 construction of the flow-pressure characteristics of the MPC showed the ability of the hydraulic transport system to produce commercial products in the form of molding sand with high-quality purification from fine and clay impurities and provide a slurry productivity of 1300 m 3 /hour, which corresponds to the calculated value of such a MPC in terms of operational productivity of 350 thousand m 3 /year. .Thus, as a result of justification of technological parameters, Planning and design office Hydraulic Technology of Mining (htmp.com.ua)managed to ensure the possibility of using the set of equipment available at the Gusarovsky MPP to obtain high-quality commercial products at minimal cost.The development of a technological complex for mining and processing, the parameters of which are justified in the work, will allow the existing enterprise to continue developing the deposit and obtain high-quality commercial products.

Figure 4 .
Figure 4. Characteristics of the GKCD2000 classifier: a) when supplying clean water; b) at a slurry concentration of 10%

Figure 5 .
Figure 5. Characteristics of the mining and processing complex when fed with: a) clean water, b) slurry concentration 10%: 1characteristics of the GKCD2000 classifier; 2area of operation of the MPC in accordance with option 2; 3area of operation of the MPC in accordance with option 3; 4area of operation of the MPC in accordance with option 1