Ores · Gravity index
Ores that answer to gravity.
Density does the separating. If the valuable mineral is heavy enough against its gangue, a shaking-table circuit will take it — test work on your sample says how much.
Ores
Seven ores. One separator.
Gold, chromite, lead and barite, pyrite, tin, tungsten, antimony — and the tailings and wastes they leave behind. Where our test work has returned a figure it is shown; where it has not, the gravity index says how the mineral should behave on a table, and test work on your sample decides.
How every plant walks the same ten steps-
Gold
free gold and gold locked in pyrite · shaking tables
Free gold is as easy as tabling gets — at SG 19.3 it sits off the top of the gravity index. Gold locked in pyrite follows its host: the dense sulphide is concentrated on rougher and cleaner shaking tables and the gold goes with it. The 300 t/h Kazakhstan flowsheet, gold entrapped in pyrite, is exactly this route.
96.1% recovery
test work · free-milling ore
Service lines that apply
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Chromite
ground to liberation · shaking tables
Chromite is ground only to liberation and concentrated on shaking tables. Concentration criterion 2.1 against quartz — workable, so the grind and the table feed are set by test work, not assumed. Chromite plant wastes have been through the same programme at Bursa.
48% Cr₂O₃
test work · gravity
Service lines that apply
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Lead & barite
galena and barite on shaking tables
Galena (SG 7.5) is one of the easiest minerals to take by gravity — concentration criterion 3.9 against quartz — and barite is tabled the same way. Both have been across a shaking-table deck at the Bursa test centre, and the Romania pyrite and lead plant chose gravity after pilot-plant test work, with shaking tables as the separators.
CC 3.9
test work at Bursa · Romania plant (pyrite & lead)
Service lines that apply
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Pyrite
shaking tables · rougher and cleaner
Pyrite carries value twice — as a product in its own right and as the host of locked gold. Ground to liberation and classified into even table feeds, it is concentrated on rougher tables and cleaned on a second bank. Pyrite on the shaking table is a standing test-work programme at Bursa; the Kazakhstan gold-in-pyrite plant and the Romania pyrite and lead plant are both gravity circuits.
300 t/h plant
Kazakhstan · gold in pyrite · Romania · pyrite & lead
Service lines that apply
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Tin
cassiterite · shaking tables
Cassiterite (SG 7.0) sits in the easy band of the gravity index at CC 3.6 against quartz — the classic shaking-table ore. Rougher tables take the bulk of the feed; cleaner tables finish the concentrate. No test-work figure of ours yet: the sample decides the grind and the table count.
CC 3.6
gravity index · test work decides
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Tungsten
wolframite · jigs and shaking tables
Wolframite (SG 7.3) answers to gravity as readily as galena — CC 3.8 against quartz. Jigs take the coarse liberated fraction ahead of the mill, so less rock is ground; shaking tables finish the fines. No published figure yet — test work on the sample decides.
CC 3.8
gravity index · test work decides
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Antimony
stibnite · shaking tables
Stibnite (SG 4.6) gives CC 2.2 against quartz — workable, not easy, so liberation size and particle shape count for more than they do with galena or cassiterite. A shaking-table programme on the sample settles the grind and the table count before anything is designed.
CC 2.2
gravity index · workable · test work decides
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Legacy tailings & wastes
lead-zinc tailings · ferrochrome wastes · chromite plant wastes
Old dumps go through the same circuit: reclaim, scrub and screen, classify, then tables and jigs. Lead-zinc tailings give up their lead — galena, CC 3.9 — while zinc recovery by gravity is limited and test work says how much. Ferrochrome metal is jigged back out of slag; chromite plant wastes have been tested at Bursa. The residue leaves dewatered and stackable, with the water recycled.
Value out.
Inert residue.chromite plant wastes tested at Bursa · zinc by gravity is limited
Service lines that apply
Recoveries, grades and plant figures are from test work and reference projects on the named ore. CC is the concentration criterion against quartz gangue in water — an index, not a result. Your sample decides.
Gravity index
Which minerals separate by gravity?
The concentration criterion compares a mineral’s density with its gangue. Above 2.5 gravity separation is easy; between 1.75 and 2.5 it is workable; between 1.25 and 1.75 it is difficult; below 1.25 the ore needs another route. Move the gangue and watch the verdicts change.
- Not by gravity < 1.25
- Difficult 1.25–1.75
- Workable 1.75–2.5
- Easy > 2.5
CC = (ρh − 1) / (ρl − 1) · water medium · gangue SG 2.65 · values rounded to one decimal
Zinc sulphide (sphalerite, SG 4.0) sits near the workable limit — which is why lead, not zinc, is what gravity recovers from old lead-zinc tailings.
Gravity first
Reject rock, not value.
A gravity plant separates with density and water, nothing else. There are no reagents to buy, dose or treat out of the process water, and the mill grinds only to the liberation size the shaking-table tests set — never finer than the ore needs. That is what keeps a BENEFSAN plant simple to run and its residue clean enough to stack.
Jigs reject barren rock at coarse sizes, before the mill — typically the single largest energy consumer on a mine site — so less rock is ground and less rock is tabled.
Shaking tables are the separators in our test work and in the plants we have laid out: pyrite, lead and barite have all been across a deck in Bursa; gold-bearing pyrite ore and chromite plant wastes have been through the test programme.
- Separators
- Shaking tables · jigs
- Reagents
- None — density and water do the separating
- Grind
- To liberation only, set by the shaking-table tests
- Test centre
- Industrial-scale testing centre and warehouse, Bursa, Türkiye
- Decides
- Liberation size · particle shape · the ore’s gravity response curve