CN113631739A - Recovery of fine chromite material - Google Patents
Recovery of fine chromite material Download PDFInfo
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- CN113631739A CN113631739A CN202080023373.4A CN202080023373A CN113631739A CN 113631739 A CN113631739 A CN 113631739A CN 202080023373 A CN202080023373 A CN 202080023373A CN 113631739 A CN113631739 A CN 113631739A
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- 239000000463 material Substances 0.000 title claims description 71
- 238000011084 recovery Methods 0.000 title description 13
- 238000000034 method Methods 0.000 claims abstract description 106
- 239000002002 slurry Substances 0.000 claims abstract description 94
- 239000000696 magnetic material Substances 0.000 claims abstract description 50
- 239000012141 concentrate Substances 0.000 claims abstract description 47
- 239000002699 waste material Substances 0.000 claims abstract description 20
- 238000007885 magnetic separation Methods 0.000 claims abstract description 18
- 238000000926 separation method Methods 0.000 claims description 36
- 239000006148 magnetic separator Substances 0.000 claims description 33
- 239000006246 high-intensity magnetic separator Substances 0.000 claims description 16
- 238000011144 upstream manufacturing Methods 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 41
- 239000002562 thickening agent Substances 0.000 description 25
- 239000011651 chromium Substances 0.000 description 16
- 230000005484 gravity Effects 0.000 description 11
- 238000002360 preparation method Methods 0.000 description 7
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 4
- 239000000701 coagulant Substances 0.000 description 4
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- 229910052804 chromium Inorganic materials 0.000 description 3
- 210000004907 gland Anatomy 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000003621 irrigation water Substances 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000010977 unit operation Methods 0.000 description 2
- 229910000604 Ferrochrome Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000003287 bathing Methods 0.000 description 1
- 229910001570 bauxite Inorganic materials 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 229910001710 laterite Inorganic materials 0.000 description 1
- 239000011504 laterite Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/02—Magnetic separation acting directly on the substance being separated
- B03C1/30—Combinations with other devices, not otherwise provided for
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B7/00—Combinations of wet processes or apparatus with other processes or apparatus, e.g. for dressing ores or garbage
Abstract
A process (10, 200) for recovering chromite fines from a slurry, the process comprising: feeding a feed slurry (68) containing chromite fines to a wet spiral beneficiation stage (14) comprising a plurality of wet spiral separators or wet spiral concentrators (32); separating the slurry (68) into a high grade chromite slurry (74), a low grade chromite slurry (76) and a first tailings stream (78) by a wet process spiral separator or wet process spiral concentrator (32); magnetically separating the low-grade chromite slurry (76) in a wet magnetic separation stage (24) into a magnetic material stream (80) and a non-magnetic material waste stream (86); and separating the high grade chromite slurry (74) and the magnetic material stream (80) into a chromite concentrate (90) and a second tailings stream (92) in a shaker stage (18).
Description
The invention relates to the recovery of fine chromite material. In particular, the present invention relates to a process for recovering fine chromite material from a slurry.
Processing chromite Ore (FeCr)2O4) The plant in (b) will typically produce tailings or tailings, typically in the form of a slurry or slime stream containing valuable chromite fines. Recovery of chromite fines from such slurry or slurry streams in a cost effective manner is difficult, especially for-75 μm chromite fines. The loss of chromite from the tailings from the chromite processing plant can be significant, with a loss of Cr in the chromite fed to the chromite processing plant of about 35-40 mass%.
Therefore, there is a need for a process for economically and efficiently recovering fine chromite material from a slurry.
According to the present invention there is provided a process for recovering chromite fines from a slurry, said process including the steps of:
feeding a feed slurry (feed slurry) comprising chromite fines to a wet spiral beneficiation stage comprising a plurality of wet spiral separators or wet spiral concentrators;
separating the slurry into a high-grade chromite slurry, a low-grade chromite slurry and a first tailings stream by a wet spiral separator or a wet spiral concentrator;
magnetically separating the low-grade chromite slurry into a magnetic material stream and a non-magnetic material waste stream in a wet magnetic separation (wet magnetic separation) stage; and
the high grade chromite slurry and magnetic material stream are separated into a chromite concentrate and a second tailings stream in a cradle stage.
"Recovery of chromite values from plant tailings by gravity concentration" (Recovery of chromite values from plant tailings by gravity beneficiation) by tripath, Sun Kumar, Ramamurthy, Y. and Singh, Veerendra (Journal of mineral and Material Characterization and Engineering), volume 10, phase 1, pages 13-25, month 2011) discloses beneficiation of chromite streams in which at least 50% of the fines are 100 to 35 μm using spiral separation and rocking machines (shake table). Tripathy, Sunil Kumar and Murthy, Y.Rama, "Multi-objective optimization of spiral concentrator for separation of ultra-fine chromite" ("International Journal of Mining and Mineral Engineering", Vol.4, vol.2, month 1 2012) also mentions spiral separation of ultra-fine chromite (spiral separation) wherein 70% of the chromite has a particle size of less than 75 μm. US 3323900, CN 101823018 and CN 201366374 mention the recovery of chromium from bauxite (laterite) using spiral separators. US 3323900, US 3935094, RU 2208060, CN 101823018, CN 201366374, ZA 2011/00444 and ZA 2014/004437 disclose magnetic separation of fines containing chromite. ZA 2005/03034 teaches mechanical cleaning of the surface of chromite crystals present in chromite fines and magnetic separation of iron oxides. US 3,323,900, CN 101823018 and CN 201366374 disclose rocking platforms for chromite recovery. However, none of these documents teach or suggest a process according to the present invention, the use of unit operations in the same order as in the process of the present invention, and the use of the same feed and product streams connecting the various unit operations.
The method may comprise subjecting the feed slurry to a feed preparation stage prior to feeding the feed slurry to the wet spiral beneficiation stage.
In the feed preparation stage, the feed slurry may be screened to separate oversized material from the feed slurry. Typically, oversized material is discharged onto a dump (dump).
The feed preparation stage may be configured to separate oversize material of +1000 μm, preferably +950 μm, more preferably +900 μm, most preferably +850 μm from the feed slurry.
During the feed preparation phase, magnetic material (e.g., tramp metal) may be magnetically separated from the feed stream in multiple wet medium intensity magnetic separators operating in parallel. Typically, the magnetic material is discharged onto a scrap heap, for example, along with oversized material.
If necessary or desired, the method may comprise: water is added to the feed slurry from the screen (i.e., to the underflow from the screen) during the feed preparation stage to reduce the consistency of the feed slurry prior to magnetically separating the magnetic material from the feed slurry.
The wet medium intensity magnetic separator may produce a magnetic flux intensity of about 0.2 tesla to about 0.8 tesla, preferably about 0.3 tesla to about 0.7 tesla, most preferably about 0.4 tesla to about 0.6 tesla, for example about 0.5 tesla.
The method may comprise: subjecting at least one of the high grade chromite pulp stream and the magnetic material stream to a size separation stage to produce one or more finer material components or underflow components and one or more coarser material components or overflow components, followed by separation of the at least one high grade chromite pulp stream and magnetic material stream in the form of at least the one or more finer material components and optionally the one or more coarser material components in a shaker stage into a chromite concentrate (concentrate) and a second tailings stream. Preferably, both the high grade chromite slurry and the magnetic material are subjected to a size separation stage.
In one embodiment of the invention, as an alternative to the way in which the coarser material component or components from the size separation stage are separated in the shaker stage, the coarser material component or components from the size separation stage are discharged as tailings.
The size separation stage typically comprises one or more screens to separate the high grade chromite slurry and the magnetic material stream into two size components, for example a +100 μm component and a-100 μm component, or a +90 μm component and a-90 μm component.
Cr of the feed slurry on a dry basis2O3The content is about 7 to about 11 mass%, for example about 9 mass%.
The feed slurry to the wet spiral beneficiation stage can comprise chromite fines such that at least 90% of the chromite fines pass through a 150 μm square mesh, or through a 125 μm square mesh, or through a 115 μm square mesh or through a 100 μm square mesh.
More than 50% or more than 60% or more than 70% or more than 80% of the chromite fines in the feed slurry to the wet spiral beneficiation stage are typically-75 μm material.
The method can comprise the following steps: the feed slurry is dewatered prior to being fed to a wet process spiral separator or wet process spiral concentrator. Dewatering of the feed slurry can be accomplished using any suitable dewatering technique or equipment (e.g., a dewatering cyclone). Generally, water removed from the feed slurry is fed to a thickener (thickner) or the like.
The specific gravity of the feed slurry to the wet process spiral separator or wet process spiral concentrator relative to water may be from about 1.2 to about 1.8, preferably from about 1.3 to about 1.7, more preferably from about 1.4 to about 1.6, for example about 1.5.
The pitch angle (pitch) of the wet process spiral separator or wet process spiral concentrator may be from about 4 ° to about 10 °, preferably from about 4 ° to about 9 °, more preferably from about 5 ° to about 8 °, for example about 6.5 °.
The wet process spiral separator or wet process spiral concentrator may have a diameter of from about 50cm to about 150cm, preferably from about 60cm to about 140cm, more preferably from about 70cm to about 130cm, for example about 90 cm.
The angle of inclination (profile) of the wet process spiral separator or wet process spiral concentrator may be from about 1 ° to about 5 °, preferably from about 1.5 ° to about 4.5 °, more preferably from about 2 ° to about 4 °, for example about 3 °.
The wet process spiral separator or wet process spiral concentrator may have a height of about 2 turns (turn) to about 6 turns, preferably about 3 turns to about 5 turns, for example about 4 turns.
Each wet process spiral separator or wet process spiral concentrator may provide a feed slurry at a rate of from about 0.5 tons/hour to about 1.5 tons/hour, preferably from about 0.6 tons/hour to about 1.4 tons/hour, more preferably from about 0.7 tons/hour to about 1.3 tons/hour, for example about 1 ton/hour.
The wet spiral separator or wet spiral concentrator may be configured such that the higher grade chromite slurry is a concentrate fraction (cut) from the wet spiral separator or wet spiral concentrator, the lower grade chromite slurry is a middlings (middlings) fraction from the wet spiral separator or wet spiral concentrator, and the first tailings stream is a tailings fraction from the wet spiral separator or wet spiral concentrator.
Typically, all wet process spiral separators or wet process spiral concentrators are roughing (rougher) spiral separators or concentrators and the process therefore does not employ a cleaning (cleaner) or a flushing (scuvenger) spiral separator or concentrator.
The wet spiral separator or wet spiral concentrator may be constructed and operated as Cr of high grade chromite slurry on a dry basis2O3The content is about 11 to about 20 mass%, preferably about 12 to about 19 mass%, more preferably about 13 to about 18 mass%, for example about 16 mass%.
The wet spiral separator or wet spiral concentrator may be constructed and operated on a dry basis as Cr for a low grade chromite slurry (i.e., middlings)2O3The content is about 6 to about 11 mass%, preferably about 7 to about 9 mass%, for example about 8 to 10 mass%.
The wet spiral separator or wet spiral concentrator may be configured and operated such that the Cr of the first tailings stream is on a dry basis2O3The content is less than about 8 mass%.
The wet spiral separator or wet spiral concentrator may be configured and operated with a mass flow ratio of high-grade chromite slurry to low-grade chromite slurry of from about 1:1.5 to about 1:2.5, for example, about 1:2, on a dry basis.
Magnetically separating the low-grade chromite slurry in the wet magnetic separation stage may comprise passing the low-grade chromite slurry through a plurality of wet high intensity magnetic separators operating in parallel. The wet high intensity magnetic separators may be roughing separators (rougher separators) that each produce a magnetic flux density of about 1 tesla (tesla) to about 1.4 tesla, such as about 1.2 tesla.
The magnetic separation of the low-grade chromite slurry in the wet magnetic separation stage may comprise: the nonmagnetic material waste stream is conveyed from the roughing separator to a further or downstream wet high intensity separator, i.e. a wash separator (scavenger separator), operating in parallel. The flushable separators may each produce a magnetic flux density of about 1 tesla to about 1.4 tesla, such as about 1.2 tesla.
If desired, the magnetic separation of the low-grade chromite slurry in the wet magnetic separation stage may include: passing a waste stream of non-magnetic material from the flush separator to at least one further downstream set of flush separators operating in parallel.
In one embodiment of the invention, the wet high intensity magnetic separators of the wet magnetic separation stage are grouped together into processing units, each processing unit comprising a roughing wet high intensity magnetic separator, followed by two downstream wash wet high intensity magnetic separators in series. The magnetic material streams from the rougher and the rinse wet high intensity magnetic separators are combined to form the magnetic material stream that is fed to the shaker stage, typically through a size separation stage.
The method may include: the one or more finer material components are dewatered prior to separation in the shaker stage into a chromite concentrate and a second tailings stream. Dewatering one or more of the finer material components can be accomplished using any suitable dewatering technique or equipment (e.g., a dewatering cyclone). Typically, the water removed from one or more of the finer material components is fed to a thickener or the like, possibly via a guard cyclone or the like.
Typically, if one or more coarser material components are separated in the shaker stage but not discharged, one or more coarser material components need not be dewatered prior to separation in the shaker stage.
The shaker stage may employ a plurality of shakers or Wilfley-type shakers for one or more finer material components, and in one embodiment of the invention, a plurality of shakers or Wilfley-type shakers for one or more coarser material components. Thus, one or more finer material components may be treated separately from one or more coarser material components in the shaker stage. The number of platforms required for one or more finer material components may be higher than the number of platforms required for one or more coarser material components.
As an alternative to the practice of separating the coarser material component or components from the size separation stage in the shaker stage, the coarser material component or components from the size separation stage are discharged as tailings.
The shaker stage may comprise: a roughing shaker upstream of the cleaning shaker. Typically, in this embodiment of the invention, one or more finer material components or underflow components from the size separation stage alone are thus fed to the rougher shaker, and one or more coarser material components from the size separation stage are discharged, for example as tailings, and are not treated in the shaker stage.
The specific gravity of the finer material component or components fed to the rocking bed relative to water may be from about 1.1 to about 1.6, preferably from about 1.2 to about 1.5, more preferably from about 1.3 to about 1.4, for example about 1.35.
In one embodiment of the invention, the concentrate components from the tables handling one or more finer material components and the tables handling one or more coarser material components form or constitute chromite concentrate. The concentrate fraction therefore consists of the most dense material from the table. Typically, chromite concentrate is dewatered (e.g. using a dewatering cyclone) and stacked in a stockpile (stockpile). The water obtained after dewatering of the chromite concentrate may be fed to a thickener, possibly through a guard cyclone or the like.
The middling and tailings fractions from each shaker may form a second tailings stream. The middling and tailings fractions from each table are less dense than the fractions without the concentrate fraction.
The method may include: the first and second tailings streams from the wet magnetic separation stage and the waste stream of non-magnetic material are combined into a tailings stream and the tailings stream is treated to recover water, for example for use as process water. The tailings stream also typically contains water from any dewatering operations performed. The treatment of the tailings stream typically involves the use of a thickener and may also include a settling pond (clarifier). The outlet of the tailings stream may comprise, if desired or necessary: the tailings stream is first passed through a guard cyclone, separated into an oversize material stream and an undersize material stream, and fed to a thickener, where the undersize material stream is processed in a tailings storage facility.
In another embodiment of the invention, wherein the process comprises treating only one or more finer material components or underflow components from the size separation stage on the rougher and cleaner beds, the process comprises further processing stages for treating at least one middling component from the cleaner bed, and the concentrate component from the cleaner bed constitutes a chromite concentrate.
Preferably, at other processing stages, the middlings fraction from the rougher shaker and the tailings fraction from the cleaner shaker will also be treated.
Other processing stages may include a rougher wet magnetic separator that receives material from the shaker stage.
Typically, the rougher wet magnetic separators of the other processing stages receive middling components from the rougher shaker, middling components from the cleaner shaker, and tailings components from the cleaner shaker.
Other processing stages may include a clean wet magnetic separator that receives magnetic material from the rougher wet magnetic separator. The non-magnetic material from the magnetic rougher separator may be discharged, for example as tailings.
The method may include: in other processing stages, the magnetic material from the clean wet magnetic separator is dewatered and the dewatered magnetic material from the clean wet magnetic separator is recycled to the clean shaker. The dewatering of the magnetic material from the clean wet magnetic separator can be accomplished using any suitable dewatering technique or equipment (e.g., a dewatering cyclone). Typically, feeding the water removed from the magnetic separated material of the clean wet magnetic separator to a thickener or the like, possibly by means of a guard cyclone or the like.
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 shows an embodiment of the process of the present invention for recovering chromite fines from a slurry; and is
Fig. 2 shows another embodiment of the process according to the invention for recovering chromite fines from a slurry.
Referring to FIG. 1 of the drawings, reference numeral 10 generally indicates the process of the invention for recovering chromite fines from a slurry. The method 10 generally includes: a feed preparation stage 12, a wet spiral dressing stage 14, a size separation stage 16, a table stage 18, a concentrate treatment stage 20, a tailings treatment stage 22 and a wet magnetic separation stage 24.
The feed preparation stage 12 is provided with a screen 26 and a plurality (e.g. 10) of wet medium intensity magnetic separators 28 operating in parallel.
The wet spiral beneficiation stage 14 is provided with a plurality of dewatering cyclones 30 and a plurality (e.g., one hundred sixty) of rougher wet spiral separators or wet spiral concentrators 32.
The wet magnetic separation stage 24 comprises: a first set of 14 wet high intensity rough magnetic separators 34 operating in parallel, a second set of wet high intensity magnetic separators 36 (also 14 operating in parallel), and a third set of wet high intensity magnetic separators 38 downstream of the second set of wet high intensity magnetic separators 36. There are also 14 wet high intensity magnetic separators 38 in the third set of wet high intensity magnetic separators 38.
The size separation stage 16 includes a pair of screens 40, 42, but a single screen may be used. Generally, in the embodiment shown in FIG. 1, screen 42 is actually a pair of screens, considering that the load of screen 42 is higher than the load of screen 40. In the embodiment shown in FIG. 1, the screens 42, 42 are 100 μm screens. In another embodiment of the invention, the screen is a 90 μm screen.
The shaker stage 18 has a plurality of dewatering cyclones 44, a plurality of (e.g. 42) to 100 μm shakers 46, and a plurality of (e.g. 24) +100 μm shakers 48.
The concentrate treatment stage 20 includes a dewatering cyclone (not shown) and a chromite stacker 50.
The tailings treatment stage 22 includes a thickener 52 and a settling tank 54.
The process 10 is configured to process about 420 tonnes/hour of feed slurry consisting of chromite fines (i.e. tailings) produced from processing of chromite ore concentrate by a chromite recovery plant (not shown). Cr of the feed slurry on a dry basis2O3The content is usually about 8 to 10 mass%. The chromite fines in the feed slurry are such that at least 90% of the chromite fines pass through a 115 μm square mesh.
The feed slurry is fed to the screen 26 through a feed slurry line 60, wherein +850 μm oversized waste material is removed through an overflow line 62. The underflow from screen 26 is fed to wet medium intensity magnetic separator 28 via underflow line 64. Magnetic waste material (e.g., iron) is removed by the wet medium intensity magnetic separator 28 and combined with oversize material from the screen 26 by the magnetic material line 66.
The wet medium intensity magnetic separators 28 each produce a magnetic flux intensity of about 0.5 tesla or about 0.6 tesla that is high enough to remove magnetic waste material (e.g., iron) and low enough to produce a non-magnetic material slurry stream containing chromite fines, which is then removed through a slurry line 68 and pumped to the dewatering cyclone 30 of the wet spiral beneficiation stage 14.
Dewatering cyclone 30 removes some of the water from the slurry, producing a slurry with a specific gravity of about 1.5 relative to water. Water removed from the slurry by the dewatering cyclone 30 is drawn through an overflow line 70 and pumped to the thickener 52.
The dense slurry is removed from dewatering cyclone 30 via underflow line 72 and fed to wet process spiral separator or wet process spiral concentrator 32. Each wet process spiral separator or wet process spiral concentrator 32 is provided with a slurry having a specific gravity of 1.5 of about 1 ton/hr. The rougher wet spiral separator or wet spiral concentrator 32 is each about 90cm in diameter, has a pitch angle of about 5 °, a pitch angle of about 1-5 °, and a height of about 4 turns. Three fractions are removed by each of the rougher wet process spiral separators or wet process spiral separators 32. The first fraction is the radially inner fraction (i.e. the high grade chromite slurry), which is removed via the concentrate line 74. The low grade slurry is the radially intermediate middlings fraction which is removed via the middlings line 76. The radially outer tailings fraction is removed as a first tailings stream and pumped through a first tailings stream line 78 to thickener 52. There is no washout spiral separator or wet spiral concentrator in the spiral concentration stage 14.
Although not shown in the drawings, process water is typically added to the high-grade and low-grade chromite slurries to reduce the slurry consistency before the slurries are pumped to the size separation stage 16 and wet magnetic separation stage 24 respectively.
Cr of the middlings fraction on a dry basis2O3Is present in an amount of about 8 to 10 mass% and represents about 40 to 50 mass% of the slurry fed to the rougher or wet spiral concentrator 32. The middlings fraction is pumped through a middlings line 76 to the wet magnetic separation stage 24 for distribution to the first set of wet high intensity magnetic separators 34 for further processing to recover the remaining chromite. The wet high intensity magnetic separators 34 act as roughing separators each producing a magnetic flux density of about 1.2 tesla. The wet high intensity magnetic separator 34 produces a magnetic material stream that is removed through a magnetic material stream line 80. The non-magnetic waste material from the wet high intensity magnetic separator 34 is gravity fed through the non-magnetic material feed line 82 to the second set of downstream wet high intensity magnetic wash separators 36, magneticThe magnetic material is again withdrawn therefrom through the magnetic material flow line 80 and the non-magnetic waste material is withdrawn therefrom through the non-magnetic material feed line 84. The nonmagnetic material feed line 84 gravity feeds nonmagnetic waste material to the third set of downstream wet high intensity flush magnetic separators 38, again producing a magnetic material stream drawn through the magnetic material stream line 80 and a nonmagnetic waste stream drawn through the nonmagnetic waste material draw line 86 (directed to the thickener 52).
The magnetic material in the magnetic material flow line 80 is pumped to the size separation stage 16 and discharged onto the screen 42 (typically actually two screens). Process water is added with a magnetic material (not shown) as needed so that the volumetric flow rate remains constant. Similarly, concentrate from the concentrate line 74 is fed to the size separation stage 16 and discharged onto the screen 40. The screens 40, 42 separate the material discharged onto the screens into a +100 μm component and a-100 μm component. Process water is sprayed onto the oversized material to wash the oversized material. The-100 μm fraction from the screens 40, 42 is pumped via a slurry line 75 to the dewatering cyclone 44 of the shaker stage 18, while the +100 μm fraction from the screens 40, 42 is fed via a slurry line 77 directly to the +100 μm shaker 48 of the shaker stage 18.
In the shaker stage 18 the-100 μm fraction is first dewatered in a dewatering cyclone 44 and the water is removed via overflow line 88, which is fed to thickener 52. The underflow of the dewatering cyclone 44 has a specific gravity relative to water of about 1.35 and is fed to a-100 μm shaker 46 via flow line 79. The-100 μm and +100 μm tables are universal weikfield type tables that separate particles based on density and size, each producing a concentrate fraction, a middlings fraction and a tailings fraction. The concentrate fraction from the-100 μm rocking bed 46 and the concentrate fraction from the +100 μm rocking bed 48 are withdrawn through the concentrate line 90 and fed to the concentrate treatment stage 20. The middlings and tailings fractions from the-100 μm and +100 μm shakers 46, 48 are combined to form a second tailings stream which is fed to the thickener 52 via a second tailings stream line 92.
In the concentrate treatment stage 20, concentrate from the concentrate line 90 uses a dewatering cyclone (not shown)Shown) and the dewatered concentrate is stacked by the chromite stacker 50 onto a concentrate stack 94. Cr of the concentrate pile 94 on a dry basis2O3The content is usually about 40 mass%.
The thickener 52 of the tailings treatment stage 22 receives a first wake from the first wake line 78, non-magnetic waste material from the non-magnetic material withdrawal line 86, a second wake from the second wake line 92, an underflow from an underflow line 104 leading from the settling pond 54 to the thickener 52, water from the dewatering cyclone 30 discharged through the overflow line 70, water from the dewatering cyclone 44 discharged through the overflow line 88, and water from the dewatering cyclone of the concentrate treatment stage 20 (not shown). Thickener 52 is provided with coagulant via coagulant feed line 96. The underflow 106 from the thickener 52 contains about 3 to 4 mass% Cr on a dry basis2O3It is discharged and pumped to tailings storage facilities. The overflow from thickener 52 is fed to the settling tank 54 through overflow line 98 and is also provided with flocculant (flocculant) from flocculant feed line 96 and coagulant (coagulunt) from coagulant feed line 100. The underflow from the settling tank 154 is returned to the thickener via underflow flow line 104 and the overflow from the settling tank 54 is drawn through process water line 102 and fed to a process water tank (not shown) for use as process water in the process 10, e.g., spray water, wash water, gland seal water (gland seal water), dilution water, and wash and irrigation water (water for flushing and bathing).
Fig. 2 shows another embodiment of the process of the present invention for recovering chromite fines from a slurry, generally indicated by the reference numeral 200. FIG. 2 is simplified over FIG. 1, which omits many of the details of the various processing stages, but rather serves to emphasize the differences between method 10 and method 200 at a summary level. However, unless otherwise indicated, the same reference numerals used in the method 10 of fig. 1 are used in the method 200 of fig. 2 to indicate the same or similar method features.
Unlike process 10, in which oversize material from screens 40, 42 of size separation stage 16 is processed in shaker stage 18, oversize material from size separation stage 16 of process 200 is discharged as tailings through oversize material withdrawal line 202. In other words, in the process 200, the oversize material from the screen of the size separation stage 16 is not further processed to recover chromite. The size separation stage 16 of the process 200 is used to remove oversize material that adversely affects the chromite recovery efficiency of the rocking bed stage 18.
Thus, another difference between method 200 and method 10 is that: in the shaker stage 18, as an alternative to the parallel processing of undersized and oversized materials from the size separation stage 16 on separate shakers 46, 48 in the process 10, the vibration table stage 18 of the process 200 has a plurality of rougher shakers 246 upstream of the plurality of cleaner shakers 248. Only the undersized material from the size separation stage 16 is fed through slurry line 75 to the shaker stage 18, dewatered in dewatering cyclone 44, and then processed on the rougher shaker 246. The rougher table 246 is used to maximise chromite recovery from the wet spiral dressing stage 14 and the wet spiral dressing stage 24. The density of the slurry fed to the rougher shaker 246 is controlled using the dewatering cyclone 44.
The rougher shaker 246 is a three-tier shaker (triple-deck scraping table) that receives the underflow from the dewatering cyclone 44 and adds wash water to the shaker 246 to improve feed material separation. The rougher table 246 serves to maximise the recovery of chromite from the high quality chromite slurry obtained from the wet spiral beneficiation stage 14 and the magnetic material obtained from the wet spiral beneficiation stage 24. Three products, namely concentrate, middlings and tailings, are recovered from the rougher shaker 246. The concentrate is fed via flow line 204 to the clean-up table 248 for further processing. Middlings from the rougher shaker 246 are fed via flow line 206 to other processing stages as will be described in more detail below. Tailings from the rougher shaker 246 are withdrawn through a second tailings stream line 92.
The clean table 248 is used to upgrade the rougher table concentrate to the chromite grade specification required for the final concentrate product. There are 16 three-layer cleaning cradles 248. The clean shaker 248 receives wash water to summarize the feed materialsAnd (5) separating materials. Three products, namely concentrate, middlings and tailings, are recovered from the clean-shaker 248. Middlings and tailings are fed to other processing stages via flow lines 208 and 210. The concentrate from the clean shaker 248 is withdrawn through the concentrate line 90 and dewatered using a stacker cyclone (not shown), and then the underflow from the stacker cyclone is stacked by the chromite stacker 50 onto the concentrate pile 94. Cr of the concentrate pile 94 on a dry basis2O3The content is usually about 40 mass%.
Other processing stages that do not form part of the process 10 include a rougher wet magnetic separator 212 upstream of the clean wet magnetic separator 214, and a dewatering cyclone 216.
Middlings from the rougher shaker 246 of the shaker stage 18 are fed to the rougher wet magnetic separator 212 via flow line 206. The rougher wet magnetic separator 212 also receives middlings and tailings from the clean shaker 248 of the shaker stage 18 via flow lines 208 and 210. The rougher wet magnetic separator 212 produces a nonmagnetic material waste stream that is withdrawn through the second tailings stream line 92 and a magnetic material stream that is conveyed from the rougher wet magnetic separator 212 to the downstream clean wet magnetic separator 214 through flow line 213.
The clean wet magnetic separator 214 also produces a non-magnetic material waste stream, which is withdrawn through the second tailings stream line 92, and a magnetic material stream, which is conveyed to the dewatering cyclone 216 through flow line 218.
Overflow from the dewatering cyclone 216 is withdrawn through a second tailings stream line 92. The underflow from the dewatering cyclone 216 is withdrawn via flow line 20 and recycled back to the clean shaker 248 of the shaker stage 18 for density control. Thus, the density of the slurry fed to the clean shaker 248 is controlled by the operation of the rougher shaker 246 and the operation of the dewatering cyclone 216 of the other processing stages 250.
Another difference between method 200 and method 10 is: the process 200 has a guard cyclone 260 forming part of the tailings treatment stage 22. In the process 200, the first tailings stream from the spiral separation stage 14 is fed via the first tailings stream line 78 to the guard cyclone 260 rather than directly to the thickener 52. Similarly, the second tailings flow line 92 and the non-magnetic waste material withdrawal line 86 lead to the guard cyclone 260 and do not lead directly to the thickener 52.
The tailings treatment stage 22 of the process 200 is shown with a tailings pumping system 270. The underflow from the shield cyclone 260 flows under gravity through flow line 262 to the tailings pumping system 270, and the overflow from the shield cyclone 260 flows under gravity through flow line 264 to the thickener 52. The underflow from thickener 52 is delivered to tailings pumping system 270 via flow line 266. A flow line 268 leads from the tailings pumping system 270 to a tailings storage facility (not shown).
The overflow from thickener 52 is drawn off via process water line 104 and fed to a process water tank (not shown) for use as process water in method 200, e.g., spray water, wash water, gland seal water, dilution water, and rinse and irrigation water. The main source of process water is thickener overflow, and if necessary, a raw water supplement (not shown) should be provided.
The process 200 is configured to process about 500 tonnes/hour of a feed slurry comprising a chromite fines (i.e. tailings) composition resulting from processing of a chromite ore run by a chromite recovery plant (not shown). Cr of the feed slurry on a dry basis2O3The content is usually about 8 to 10 mass%. The chromite fines in the feed slurry are such that at least 90% of the chromite fines pass through a 115 μm square mesh.
The processes 10, 200 as shown recover chromite concentrate, on a dry basis, of Cr from the chromite concentrate in an economically efficient manner2O3The content is at most about 40 mass%. With only a relatively small fraction of Cr in the feed slurry2O3(e.g., about 4-5% on a dry matter basis) is discharged from thickener 52 as a waste material. Thus, the methods 10, 200 as shown can advantageously recover a substantial portion of the chromium (as Cr)2O3) Even when the majority of chromite fines are-75 μm.
Claims (15)
1. A process for recovering chromite fines from a slurry, said process comprising:
feeding a feed slurry comprising chromite fines to a wet spiral beneficiation stage comprising a plurality of wet spiral separators or wet spiral concentrators;
separating the slurry into a high-grade chromite slurry, a low-grade chromite slurry and a first tailings stream by a wet spiral separator or a wet spiral concentrator;
magnetically separating the low-grade chromite slurry into a magnetic material flow and a non-magnetic material waste flow in a wet magnetic separation stage; and
the high grade chromite slurry and magnetic material stream are separated into a chromite concentrate and a second tailings stream in a cradle stage.
2. The method of claim 1, wherein the Cr of the feed slurry2O3The content is from 7 to 11 mass% and/or the feed slurry to the wet spiral beneficiation stage comprises chromite fines such that at least 90% of the chromite fines pass through a 150 μm square mesh, or through a 125 μm square mesh, or through a 115 μm square mesh, or through a 100 μm square mesh.
3. The process of claim 1 or claim 2, wherein magnetically separating the low-grade chromite slurry in the wet magnetic separation stage comprises: passing the low grade chromite slurry through a plurality of wet high intensity roughing magnetic separators operating in parallel and passing the non-magnetic material waste stream from the roughing magnetic separators to a wet high intensity magnetic separator further downstream in parallel which is a rinse separator.
4. The method of any one of claims 1 to 3, the method comprising: subjecting at least one of the high grade chromite pulp stream and the magnetic material stream to a size separation stage to produce one or more finer material components or underflow components and one or more coarser material components or overflow components, followed by separation of the at least one high grade chromite pulp stream and magnetic material stream in the form of at least the one or more finer material components and optionally the one or more coarser material components in a table concentrator stage into a chromite concentrate and a second tailings stream.
5. A process according to claim 4, wherein the rocking bed stage employs a plurality of rocking beds for one or more finer material fractions and a plurality of rocking beds for one or more coarser material fractions, whereby the one or more finer material fractions are processed independently of the one or more coarser materials in the rocking bed stage.
6. A process according to claim 4 wherein the coarser material fraction or fractions from the size separation stage are discharged as tailings as an alternative to separating the coarser material fraction or fractions from the size separation stage in the shaker stage.
7. The process of claim 6, wherein the shaker stage comprises a rougher shaker upstream of the cleaner shaker and the one or more finer material components from the size separation stage are fed to the rougher shaker.
8. The process according to claim 7, comprising a further processing stage for treating at least the middling fraction from the clean bench and the concentrate fraction from the clean bench constitutes chromite concentrate.
9. A process according to claim 8, wherein in the further processing stage the middlings fraction from the rougher shaker and the tailings fraction from the cleaner shaker are also treated.
10. The process defined in claim 8 or claim 9 wherein the further processing stage includes a rougher wet magnetic separator that receives material from the table stage.
11. The process of claim 10 wherein the rougher wet magnetic separator of the further processing stage receives middling components from the rougher shaker, middling components from the cleaner shaker and tailings components from the cleaner shaker.
12. A method according to any one of claims 8 to 11, wherein the further processing stage comprises: a clean wet magnetic separator that receives magnetic material from the rougher wet magnetic separator and the non-magnetic material from the rougher magnetic separator is discharged as tailings.
13. The method of claim 12, the method comprising: in the further processing stage, the magnetic material from the clean wet magnetic separator is dewatered and the dewatered magnetic material from the clean wet magnetic separator is recycled to the clean shaker.
14. The process of any one of claims 1 to 13, wherein the wet spiral separator or wet spiral concentrator is configured and operated to condition the Cr of the high grade chromite slurry2O3The content of Cr in the low-grade chromite slurry is 11-20% by mass on a dry basis2O3The content is 6 to 11 mass% on a dry basis and the Cr of the first tailings stream2O3The content is less than 8 mass% on a dry basis.
15. A process according to any one of claims 1 to 14, wherein more than 50%, or more than 60%, or more than 70%, or more than 80% of the chromite fines in the feed slurry fed to the wet spiral beneficiation stage are-75 μm material.
Applications Claiming Priority (3)
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| ZA201901722 | 2019-03-20 | ||
| ZA2019/01722 | 2019-03-20 | ||
| PCT/IB2020/051627 WO2020188379A1 (en) | 2019-03-20 | 2020-02-26 | Recovery of chromite fines |
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| CN113631739A true CN113631739A (en) | 2021-11-09 |
| CN113631739B CN113631739B (en) | 2024-03-22 |
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| EP (1) | EP3914740B1 (en) |
| CN (1) | CN113631739B (en) |
| CY (1) | CY1126134T1 (en) |
| DK (1) | DK3914740T3 (en) |
| EA (1) | EA202192514A1 (en) |
| ES (1) | ES2953087T3 (en) |
| FI (1) | FI3914740T3 (en) |
| WO (1) | WO2020188379A1 (en) |
| ZA (1) | ZA202001193B (en) |
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| CN113941441A (en) * | 2021-10-14 | 2022-01-18 | 中钢集团马鞍山矿山研究总院股份有限公司 | Wet-type strong magnetic preselection method for low-grade chromite |
| CN116943856B (en) * | 2023-09-20 | 2023-11-28 | 矿冶科技集团有限公司 | Method for effectively recovering chromite |
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| US4295881A (en) * | 1979-04-23 | 1981-10-20 | Texasgulf Inc. | Process for extraction of platinum group metals from chromite-bearing ore |
| CN101890394A (en) * | 2009-05-23 | 2010-11-24 | 魏子贺 | Ore dressing process for weakly magnetic iron ore |
| JP2014196569A (en) * | 2014-06-05 | 2014-10-16 | 住友金属鉱山株式会社 | Chromite recovery method |
| CN206965906U (en) * | 2017-07-24 | 2018-02-06 | 大连地拓环境科技有限公司 | A kind of iron tailings recycling treatment system |
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| US3323900A (en) | 1964-08-13 | 1967-06-06 | Fuji Iron & Steel Co Ltd | Process for treatment of iron oxide ores containing nickel, chromium and cobalt |
| US3935094A (en) | 1974-10-10 | 1976-01-27 | Quebec Iron And Titanium Corporation - Fer Et Titane Du Quebec, Incorporated | Magnetic separation of ilmenite |
| US4059506A (en) * | 1975-05-23 | 1977-11-22 | United States Steel Corporation | Ore tailings treatment |
| RU2208060C2 (en) | 2001-05-23 | 2003-07-10 | Калмукшев Сатвалде Ромазанович | Method for producing chromite concentrates from lean disseminated chrome iron bearing ores |
| ZA200503034B (en) | 2004-04-19 | 2005-12-28 | Paul Kruger Family Trust | Beneficiation of chromite ore |
| CN201366374Y (en) | 2008-12-30 | 2009-12-23 | 中国恩菲工程技术有限公司 | Laterite chromium-separating facility |
| CN101823018B (en) | 2009-03-05 | 2013-03-06 | 中国恩菲工程技术有限公司 | Method for selecting chromium from laterite |
| ZA201404437B (en) | 2013-03-19 | 2015-08-26 | Khulasonke Transp Cc | A method of treating a chromite containing material |
| AP2015008650A0 (en) * | 2014-06-02 | 2015-08-31 | Mintek | Smelting of low grade chromite concentrate fines |
-
2020
- 2020-02-26 EP EP20712025.4A patent/EP3914740B1/en active Active
- 2020-02-26 CN CN202080023373.4A patent/CN113631739B/en active Active
- 2020-02-26 DK DK20712025.4T patent/DK3914740T3/en active
- 2020-02-26 ZA ZA2020/01193A patent/ZA202001193B/en unknown
- 2020-02-26 ES ES20712025T patent/ES2953087T3/en active Active
- 2020-02-26 WO PCT/IB2020/051627 patent/WO2020188379A1/en active Search and Examination
- 2020-02-26 FI FIEP20712025.4T patent/FI3914740T3/en active
- 2020-02-26 EA EA202192514A patent/EA202192514A1/en unknown
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| US4295881A (en) * | 1979-04-23 | 1981-10-20 | Texasgulf Inc. | Process for extraction of platinum group metals from chromite-bearing ore |
| CN101890394A (en) * | 2009-05-23 | 2010-11-24 | 魏子贺 | Ore dressing process for weakly magnetic iron ore |
| JP2014196569A (en) * | 2014-06-05 | 2014-10-16 | 住友金属鉱山株式会社 | Chromite recovery method |
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Also Published As
| Publication number | Publication date |
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| WO2020188379A1 (en) | 2020-09-24 |
| CN113631739B (en) | 2024-03-22 |
| ZA202001193B (en) | 2022-05-25 |
| CY1126134T1 (en) | 2023-11-15 |
| EA202192514A1 (en) | 2021-12-13 |
| EP3914740A1 (en) | 2021-12-01 |
| FI3914740T3 (en) | 2023-08-17 |
| EP3914740B1 (en) | 2023-05-17 |
| DK3914740T3 (en) | 2023-08-14 |
| ES2953087T3 (en) | 2023-11-08 |
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