RU2781003C1 - Screw separator - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: proposed invention relates to mining, namely to a processing device, and can be used to detect fine fractions of a valuable component from hydraulic suspension during dense grinding in the mining industry. The screw separator has a hollow round post with holes, a screw chute located around the stud, a loading device located in the upper part, a design of a device for selection and withdrawal of enrichment products installed in the lower part of the chute. The screw chute in the radial section is made with a straight, rectilinear in the horizontal direction. The screw chute is made with variable radii and pitch, decreasing up and down, with the ratio

, where t is the helical pitch, R is the chute radius. The rack is equipped with cut-off pockets located at the holes.

EFFECT: increasing the efficiency of extracting a valuable component, as well as increasing the throughput of the screw separator.

1 cl, 3 dwg

Description

The invention relates to the enrichment of minerals, in particular, to screw separators used in the enrichment of finely dispersed mineral raw materials in the mining industry, and can be used both in mining and processing, and in metallurgical and other industries.

Screw separators are known, including a vertical round rack, a screw chute located around the rack, a loading device located in the upper part of the structure, a device for separating and discharging enrichment products located in the lower part (see Shokhin V.N., Lopatin A. G. Gravitational enrichment methods, Moscow: Nedra, 1993, pp. 249-260.

The disadvantage of these separators is the low catching efficiency for fine classes (-0.1 mm) of particles of a valuable component, which are in suspension in the suspension. Such structures are used for enrichment of sands with a solids content in the pulp with grain size of -3 + 0.1 mm.

The closest to the proposed solution in terms of technical essence is a screw separator for mineral processing, including a hollow round rack with holes, a screw chute located around the rack, a loading device located in the upper part of the structure, a device for separating and outputting separation products installed in the lower part of the gutter (see patent RU No. 2306181, C1, B03V 5/52 dated 12/23/2005, publ. 09/20/2007).

The disadvantage of this design is the low throughput of the original feed due to the need to pass the original pulp through all the turns of the trough and significant losses of heavy fine minerals, for example, gold of size class -0.1 mm, in the concentrate at the outlet due to the weak centrifugal forces of inertia that occur during the enrichment of the pulp in the form of a suspension in which the solid phase is in suspension.

The technical result of the invention is to increase the capacity of the screw separator and increase the efficiency of extracting a valuable component from the suspension by increasing the centrifugal forces of inertia.

где t - винтовой шаг, R - радиус желоба, а стойка снабжена отсекающими карманами, расположенными у отверстий.The essence of the invention lies in the fact that a screw separator, including a hollow column of circular cross section with holes, a screw chute located around the column, a loading device located in the upper part of the structure, a device for separating and outputting separation products installed in the lower part of the chute, differs in that that the screw chute in the radial section is made with a bottom that is rectilinear in the horizontal direction, the screw chute is also made with variable radius and pitch, decreasing from top to bottom, while the ratio

where t is the helical pitch, R is the radius of the gutter, and the post is provided with cut-off pockets located at the holes.

The use of the shape of the chute in a radial section with a straight bottom in the horizontal direction allows the unimpeded movement of solid particles in suspension in the direction of the emerging centrifugal forces of inertia to the outer side of the chute, and the joint decrease in the radius and pitch of the screw chute from top to bottom increases the emerging centrifugal forces of inertia, which, in in turn, enhances the effect of moving particles heavy in density from the center to the outer side of the chute, thereby increasing the trapping ability of the structure for fine fractions of the valuable component. The design of a vertical hollow rack of circular cross section with holes and the provision of holes with pockets for cutting off part of the flow in the chute adjacent to its inner side at the rack with holes allows cutting off and diverting the unproductive part of the hydraulic suspension flow, thereby increasing the capacity of the separator for the initial feed.

In FIG. 1 shows a general view of the separator; in fig. 2 - section A-A in Fig. one; in fig. 3 - diagrams of changing parameters along the height of the helical part of the separator.

The screw separator (Fig. 1; 2) consists of a vertical hollow post of circular cross section 1, a screw chute 2 located around the post, a loading device 3, a device for separating and withdrawing enrichment products 4, cutting off pockets of a part of the flow adjacent to the post, 5.

Thin-layer separator works as follows (Fig. 1).

The initial power (hydraulic suspension) through the loading device 3 is fed into the upper part of the screw chute 2. The flow, moving from top to bottom along the helical surface, due to the centrifugal forces of inertia, transfers heavy solid particles of the hydraulic suspension to the outer side of the chute in the radial direction from the center, and the resulting the non-productive part of the flow, adjacent to the post, is partially diverted through the cut-off pockets 5 into the hollow post 1 (Fig. 1; 2) and output to the tails. In this case, pockets are installed on each turn, starting from the second or third in height. In the lower part of the trough, the flow is divided into concentrate and tailings and is discharged through device 4 to the outside.

что дает возможность сохранить окружную скорость потока (V_ок), как и в винтовом сепараторе аналога, у которого R=const и t=const., при одинаковой высоте винтовой поверхности (h), фиг. 3. Применив теорему об изменении кинетической энергии, определим продольную скорость частицы в желобе. Если

где V_п0 и V_п - начальная и конечная продольные скорости частицы, g - ускорение свободного падения, m - масса частицы, то при V_п0=0 получаем

и тогда определяется окружная скорость как V_ок=V_в⋅ctg(ϕ), а полный пройденный путь частицей составит

Эти соотношения показывают, что радиус и шаг витков не оказывают влияние на кинематические параметры перемещающейся частицы, а уменьшающийся сверху вниз радиус увеличивает центробежную силу инерции, так как

где аⁿ - нормальное ускорение, что в свою очередь, создает дополнительное силовое воздействие на твердые частицы, повышая тем самым эффект по переводу тонкодисперсных частиц в зону формирования концентрата. Так, например, при уменьшении радиуса и шага в три раза, сила инерции увеличивается тоже в три раза с F₁ до F₂, (фиг. 3).Let us consider the effect of varying values of the radius (R) and pitch (t) of the helical surface on the emerging centrifugal inertia forces (F) acting on a particle of mass m. The variable radius of the turns (R), in combination with the proportionally changing pitch (t), form a constant chute angle (ϕ), since

which makes it possible to maintain the circumferential flow velocity (V _ok ), as in the analogue screw separator, in which R=const and t=const., with the same height of the helical surface (h), Fig. 3. Applying the theorem on the change in kinetic energy, we determine the longitudinal velocity of the particle in the chute. If a

where V _p0 and V _p are the initial and final longitudinal velocities of the particle, g is the free fall acceleration, m is the mass of the particle, then with V _p0 = 0 we obtain

and then the peripheral speed is determined as V _ok \u003d V _in ⋅ctg (ϕ), and the total path traveled by the particle will be

These relationships show that the radius and pitch of the turns do not affect the kinematic parameters of the moving particle, and the radius decreasing from top to bottom increases the centrifugal force of inertia, since

where a ⁿ - normal acceleration, which in turn creates an additional force on the solid particles, thereby increasing the effect of the transfer of fine particles in the concentrate formation zone. So, for example, when the radius and step decrease three times, the inertia force also increases three times from F ₁ to F ₂ (Fig. 3).

The volumes of discharged flows from the chute to the hollow rack are determined constructively through the dimensions of the cut-off pockets and holes in the rack with a change from Q _max to Q _min (Fig. 3). If each pocket cuts off up to 10% of the volume of the passing hydraulic suspension, then at the outlet of the chute with 7 pockets, 51% of the original flow will remain.

от t_max=0,36 м до t_min=0,12 м, состоящего из 8 витков. При этом высота винтовой части (h) составит 1,92 м, угол наклона желоба по его среднему радиусу

а его длина

м. За твердую фазу гидровзвеси примем полиминеральную смесь, состоящую из пустой породы (кварц) класса крупности -0,1 мм и плотности ρ_к=2650 кг/м³, а за ценный компонент - тяжелую фракцию (золото) той же крупности с плотностью ρ_з=19000 кг/м³. Время перемещения частиц по средней винтовой линии составит 7=2,8 с.Example. Let us consider the influence of the variable radius of the helical surface (R) and its pitch (t) on the emerging centrifugal forces of inertia (F) of the solid particles of the hydraulic suspension and their location in the separator chute. As a basis, we take a screw separator with varying radii from R _max =0.6 m to R _min = 0.2 m and a step at

from t _max =0.36 m to t _min =0.12 m, consisting of 8 turns. In this case, the height of the helical part (h) will be 1.92 m, the angle of inclination of the chute along its average radius

and its length

m. For the solid phase of the hydraulic suspension, we will take a polymineral mixture consisting of waste rock (quartz) with a size of -0.1 mm and a density of ρ _to = 2650 kg / m ³ , and for a valuable component - a heavy fraction (gold) of the same size with a density ρ _s \u003d 19000 kg / m ³ . The time of particle movement along the middle helix will be 7=2.8 s.

м/с, окружная скорость V_ок=V_ncosϕ=4,26 м/с, а на выходе из желоба -

где g - ускорение свободного падения.We assume that solid particles are in suspension. The shape of the bottom of the gutter in the radial section is taken in the form of a horizontal line (Fig. 1). The longitudinal velocity of particles (V _n ) along the center of the trough, based on the theorem on the change in kinetic energy (under initial conditions V _n0 =0), will be on average turns

m / s, peripheral speed V _ok \u003d V _n cosϕ \u003d 4.26 m / s, and at the outlet of the gutter -

where g is the free fall acceleration.

кг, а для кварца - m_к=1,7-10^-10 кг. Центробежные силы инерции на средних витках

для золота - F_з=5,7-10^-8 Η, для кварца - F_к=0,8-10^-8 Н. Сила сопротивления вязкой среды P_c=3πμV_Rd_э, где μ - динамический коэффициент вязкости воды μ=10^-3 Па⋅с, V_R - скорость частиц в радиальном направлении. С учетом принятых значений, получаем Р_с=4,7⋅10^-7⋅V_R Η. Дифференциальное уравнение движения частиц в радиальном направлении принимает вид

или

где b – для частиц из золота и кварца, для принятых величин b=45, а k=0,4·10³ - для золота, k=2,9⋅10³ - для кварца. Интегрируя это уравнение, получаем

Тогда, с учетом числовых значений, скорость частиц в средних витках достигает значений V_Rз=0,11 м/с - для золота и V_Rк=0,015 м/с - для кварца, при этом радиальное смещение (S) частиц от центра желоба составит соответственно S_з=0,34 м и S_к=0.04 м. Это означает, что тяжелые частицы (из золота при d_э<0,l мм) достигают внешнего борта желоба, в отличие от частиц пустой породы (из кварца), у которых радиальное смещение в 8,5 раз ниже. В сравнении с аналогами, у которых концентрат формируется у внутреннего борта желоба, в предлагаемой конструкции для обогащения полиминеральной гидровзвеси, этот процесс протекает у внешнего борта.Let's compare the change in the position of particles under the action of centrifugal forces of inertia in the radial direction from the center of the trough for two particles (made of gold and quartz), with the same equivalent diameter (d _e ), assuming d _e = 0.05 mm and assuming that they are in the flow in suspension. The mass of a gold particle will be

kg, and for quartz - m _k \u003d 1.7-10 ^-10 kg. Centrifugal forces of inertia on medium turns

for gold - F _c \u003d 5.7-10 ^-8 Η, for quartz - F _c \u003d 0.8-10 ^-8 N. The resistance force of a viscous medium P _c \u003d 3πμV _R d _e , where μ is the dynamic coefficient of water viscosity μ =10 ^-3 Pa⋅s, V _R - speed of particles in the radial direction. Taking into account the accepted values, we obtain P _c =4.7⋅10 ^-7 ⋅V _R Η. The differential equation for the motion of particles in the radial direction takes the form

or

where b - for particles of gold and quartz, for the accepted values b=45, and k=0.4·10 ³ - for gold, k=2.9⋅10 ³ - for quartz. Integrating this equation, we get

Then, taking into account the numerical values, the particle velocity in the middle turns reaches the values V _Rz = 0.11 m/s - for gold and V _Rk = 0.015 m/s - for quartz, while the radial displacement (S) of particles from the center of the trough will be respectively S _z = 0.34 m and S _k = 0.04 m. This means that heavy particles (from gold with d _e <0.l mm) reach the outer side of the chute, in contrast to the particles of waste rock (from quartz), y which the radial displacement is 8.5 times lower. In comparison with analogues, in which the concentrate is formed at the inner side of the trough, in the proposed design for the enrichment of polymineral hydraulic suspension, this process takes place at the outer side.

The use of the proposed technical solution makes it possible to increase the productivity of the separator, for example, when enriching gold-bearing slurry from the washing of metal-bearing sands in alluvial deposits, as well as to increase the trapping capacity of the device for fine classes of a valuable component.

Claims (1)

Screw separator, including a hollow column of circular cross section with holes, a screw chute located around the column, a loading device located in the upper part of the structure, a device for separating and removing separation products installed in the lower part of the chute, characterized in that the screw chute in the radial section is made with a bottom that is rectilinear in the horizontal direction; also, the screw chute is made with variable radius and pitch, decreasing from top to bottom, while the ratio

where t is the helical pitch, R is the radius of the gutter, and the post is provided with cut-off pockets located at the holes.

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