APPARATUS, METHOD AND PROCESS FOR THE RECOVERY OF MINERALS

Abstract

This invention relates to an inverted up-flow separator, its use in a method of recovering target mineral particles from tailings and a process for the recovery of target mineral particles from tailings using the inverted up-flow separator of the invention.

Claims

1. An inverted up-flow separator for the separation and recovery of target minerals, selected from the group consisting of fine and ultra-fine minerals, from a feed including particulate matter which comprises target mineral particles and gangue particles, the inverted up-flow separator including: (a) at least one working fluid inlet; an upper column; a feed inlet, for a feed including particulate matter which comprises target mineral particles and gangue particles, into the upper column; a lower column; a recovered product outlet; the upper column and lower column being in fluid flow communication with each other; a connecting member, connecting the upper column and lower column; and wherein: (b) the feed inlet has a feed outlet, the position at which the feed outlet terminates, in the inverted up-flow separator, being adjustable to optimise the discharge of feed in the inverted up-flow separator, (c) the upper column has a greater diameter than a diameter of the lower column; and (d) the upper column and lower column are configured and dimensioned such that upon introduction of an up-flow working fluid into the lower column, through the at least one working fluid inlet, the particulate matter in the inverted up-flow separator, when filled with fluid, is fluidised thereby imparting a first up-flow velocity (V.sub.1) to the particulate matter in the lower column and a second up-flow velocity (V.sub.2) to the particulate matter in the upper column, wherein the first up-flow velocity (V.sub.1) is greater than the second up-flow velocity (V.sub.2) and wherein the ratio of the first up-flow velocity (V.sub.1) imparted to the particulate matter in the lower column to the second up-flow velocity (V.sub.2) imparted to the particulate matter in the upper column is between 1:0.6 to 1:0.8.

2. The inverted up-flow separator of claim 1, wherein the connecting member is frustoconical in shape and defines an inner volume between the upper column and the lower column to which it is connected.

3. The inverted up-flow separator of claim 2, wherein the feed inlet has a feed outlet, the feed outlet terminating at or near where the connecting member and upper column meet and wherein the feed is discharged into the inner volume defined by the frustoconical shaped connecting member.

4. The inverted up-flow separator of claim 1, wherein the recovered product outlet is at the bottom end of the lower column for recovered target mineral particles having a higher specific gravity than the gangue particles.

5. The inverted up-flow separator of claim 1, wherein the recovered product is an outflow outlet at or near the top end of the upper column for recovered target mineral particles having a lower specific gravity than the gangue particles.

6. A method for the separation and recovery of target minerals from a feed including particulate matter which comprises target mineral particles and gangue particles, the method including the steps of: (a) using an inverted up-flow separator as claimed in claim 1, wherein the inverted up-flow separator is filled with fluid; (b) introducing the feed comprising target mineral particles and gangue particles, into an upper column of the inverted up-flow separator; (c) providing an up-flow working fluid from a fluid supply means in fluid flow communication with the at least one working fluid inlet of the inverted up-flow separator; and (d) maintaining a consistent up-flow of fluid thereby imparting upon the particulate matter a higher up-flow velocity in a lower column of the inverted up-flow separator than the up-flow velocity imparted upon particulate matter in the upper column.

7. The method of claim 6, wherein the target mineral particles have at least partially been liberated through one or more processes selected from crushing, grinding and sizing.

8. The method of claim 6, wherein the feed is sourced from tailings which include target mineral particles and gangue particles from a preceding inefficient separation of liberated target mineral particles and gangue particles.

9. The method of claim 8, wherein the feed includes particulate matter from tailings of fine and ultra-fine minerals selected from the group consisting of chromite (in the form of FeCr.sub.2O.sub.4), magnetite (in the form of Fe.sub.3O.sub.4), coal, mineral sands, free gold and cassiterite (in the form of SnO.sub.2).

10. A process for the separation and recovery of target minerals from a feed including particulate matter which comprises target mineral particles and gangue particles, the process including: (a) classifying the particulate matter into particle size bands using at least one screen and panel to obtain a first recovered product of classified particulate matter including target mineral particles and gangue particles; and (b) separating the target mineral particles from the gangue particles in the first recovered product using the separator of claim 1 to obtain a second recovered product including a higher concentration of target mineral particles to gangue particles.

11. The process of claim 10, wherein the panel includes apertures sized from between 10 micrometres to 150 micrometres.

12. A process for the separation and recovery of target minerals from a feed including particulate matter which comprises target mineral particles and gangue particles, the process comprising: (a) liberating target minerals from run of mine ore to produce an intermediate product of particulate matter including liberated target mineral particles and gangue particles; (b) separating and recovering the liberated target mineral particles from the gangue particles of the intermediate product through at least one spiral separator wherein at least some of the smaller sized target mineral particles and gangue particles are not fully recovered by the separation and are sacrificed to tailings; (c) classifying the tailings of smaller sized target mineral particles into particle size bands using at least one screen and panel to obtain a first recovered product of classified particulate matter including target mineral particles and gangue particles, wherein at least some of the smaller sized target minerals and gangue particles are not fully recovered in the first recovered product; and (d) separating the target mineral particles from the gangue particles in the first recovered product using a separator according to claim 1 to obtain a second recovered product including a higher concentration of target mineral particles to gangue particles.

13. The process of claim 12, wherein ultra-fine mineral particles having a particle size of less than 20 micrometres, not being part of the first recovered product, are subjected to further separation from gangue particles by means of a belt-type wet magnetic separator.

14. The process of claim 12, wherein ultra-fine mineral particles having a particle size of less than 20 micrometres, not being part of the second recovered product, are scavenged by means of a belt-type wet magnetic separator.

Description

DESCRIPTION OF THE FIGURES

[0087] FIG. 1: is a detailed schematic of the up flow inverted separator according to the invention as well as a cut away section A-A of the inverted up-flow separator.

[0088] FIG. 2: is a simplified diagram of the up flow inverted separator.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE FIGURES

[0089] Referring to FIG. 1, an inverted up-flow separator according to the invention is designated by the numeral 10.

[0090] The separator (10) is filled with water.

[0091] The separator (10) includes an upper column (12) and a lower column (14) that are in fluid flow communication with each other, and which are connected by a connecting member (16). The diameter of the upper column (12) is greater than the diameter of the lower column (14).

[0092] The connecting member (16) has a frustoconical shape and defines an inner volume therein.

[0093] A feed inlet (18) is provided which has a feed outlet (20) which extends into the upper column (12). The feed outlet (20) terminates at or near an end of the upper column (12) and a beginning of the connecting member (16). It will be appreciated that the position of the feed outlet (20) may be adjusted to achieve an optimal concentration of target mineral in the recovered product (not shown).

[0094] A fluid supply means (not shown) pumps fluid into multiple working fluid inlets (22) in the lower column (14) to fluidise the particles of mineral target and gangue thereby creating a working up-flow of fluid. The fluid supply means (not shown) also discharges fluid into the recovered product (not shown) which exits the recovered product outlet (24) in the lower column (14) in order to dilute the recovered product and allow it to run freely from the recovered product outlet (24) to avoid any blockages that may occur.

[0095] The source of fine and/or ultra-fine minerals to be recovered using the inverted up-flow separator is tailings. The tailings may be historic or current.

[0096] For present purposes, the process of the invention is exemplified with reference to current tailings derived from run of mine ore.

[0097] Accordingly, in use, run of mine ore (not shown) is processed to liberate target mineral particles from the ore. The method of liberation is well known to those skilled in the art and may include crushing, grinding and sizing to produce an intermediate product. Unliberated target mineral particles in the ore that do not pass through the aperture size of the screen will be recycled back to the crusher and/or grinder.

[0098] The liberated mineral particles and gangue particles are then fed through at least one spiral separator to recover the liberated mineral particles. It will be appreciated that particulate matter including smaller sized target mineral particles and gangue particles (fine and/or ultra-fine minerals) will not all be recovered and will, in prior art processes, be sacrificed to tailings.

[0099] Tailings are usually dumped as waste and often times it is not economically feasible to further process the tailings because further processing the tailings is unlikely to yield a recovered product having a sufficient concentration of mineral particles to gangue particles that would make the product commercially viable.

[0100] In the present invention however, current tailings including the smaller mineral particles and gangue particles (fine and/or ultra-fine minerals) are classified into particle size bands for separation using the inverted up-flow separator.

[0101] The classification takes place using at least one screen and panel, the panel having an aperture size of from 38 to 150 micrometres. Multiple stacked screen and panel configurations may also be used.

[0102] The resultant classified product of fine and ultra-fine mineral particles and gangue particles is then fed into the inverted up-flow separator (10), wherein the classified product is fed into the separator (10) through the feed inlet into the upper column.

[0103] The feed outlet (20) extends into the upper column (12) as shown in FIG. 1 and the fine and ultra-fine minerals and gangue enter the inner volume defined by the frustoconical connecting member (16).

[0104] When the separator (10) is in a steady state, water, which is pumped consistently into the lower column (14) through multiple water inlets (22), creates an up flow working fluid through both columns and the connecting member (16).

[0105] Fine and ultra-fine minerals report to the lower column (14) while gangue reports to the upper column (12). Where some of the fine and ultra-fine minerals get misplaced into the upper column (12), these will eventually report to the lower column (14), as the up-flow velocity V.sub.2 of particles in the upper column (12) is lower than the up flow velocity V.sub.1 in the lower column (14).

[0106] In order to prevent the build-up of recovered product at the recovered product outlet (24) of the lower column (14) water from the water supply means that supplies water to the multiple inlets in the lower column is also fed into the recovered product in order to dilute it thereby increasing its fluid flow properties.

[0107] The recovered product may then be further processed.

[0108] The invention will now be described with reference to the following non limiting examples:

EXAMPLE

[0109] For purposes of this example, and with reference to FIG. 2:

TABLE-US-00001 V.sub.1 Fluid velocity in lower column (cm/h) V.sub.2 Fluid velocity in upper column (cm/h) V.sub.2/V.sub.1 Dynamic Ratio A.sub.1 Cross-sectional area of lower column (m.sup.2) A.sub.2 Cross-sectional area of upper column (m.sup.2)

TABLE-US-00002 A.sub.2/A.sub.1 Static ratio R.sub.u Upper column radius (m) D.sub.u Upper column diameter (m) R.sub.l Lower column radius (m) D.sub.l Lower column diameter (m) Q.sub.l Volumetric flow rate lower column (l/h) Q.sub.u Volumetric flow rate upper column (l/h) Q.sub.feed Feed volumetric flow rate (l/h) Q.sub.UF Underflow volumetric flow rate (l/h) Q.sub.UP Up-flow volumetric flow rate - water box (l/h)

[0110] For purposes of this example it is assumed that the feed material has been classified to, nominally, 38 .Math.m -63 .Math.m and has a head-grade of 20% Cr.sub.2O.sub.3. The operational parameters given in table 1 hereunder result in 41% Cr.sub.2O.sub.3 with a recovery of 85%.

[0111] Recovery is defined below as

[00001]$recovery=\frac{productgrade\times productmass}{feedgrade\times feedmass}$

[0112] The cross-sectional areas of the upper column are related according to the static ratio defined as:

[00002]$staticratio=\frac{A_2}{A_1}$

[0113] The velocities V.sub.1 and V.sub.2 were optimised empirically. The length of the lower column, for purposes of this example, was 1000 mm whilst the length of the upper column was 550 mm.

[0114] Table 1 gives the operational parameters as well as critical separator dimensions for this example.

TABLE-US-00003 Operational Parameters V.sub.2 154 (cm/h) V.sub.1 220 (cm/h) V.sub.2/V.sub.1 0.7 A2 0.071 (m2) A.sub.1 0.018 (m2) Ru 0.15 (m) Du 0.3 (m) Ri 0.075 (m) Di 0.15 (m) Q.sub.l 38.9 (l/h) Q.sub.u 108.9 (l/h) Qfeed 70 (l/h) Q.sub.UF 11.7 (l/h) Q.sub.UP 50.5 (l/h)

[0115] It will be appreciated that the above is merely an example and that the separation and recovery of target minerals may take place in a different manner without departing from the spirit and scope of the invention. For example, target minerals need not be recovered from tailings emanating from run of mine ore. It may also not be necessary to engage in the crushing, grinding, sizing and separation using spiral separators and that the apparatus according to the invention may be used as a one pass separator to render a commercially viable recovered product.