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BACKGROUND
In 1985, the International Tin Council and the price of tin collapsed. This catalyzed an increased demand for metallurgical efficiencies in tin operations worldwide and resulted in the wider use of tin flotation and multi-gravity separation techniques operating either in isolation or together to maximize metallurgical efficiencies. In the wake of this, a variety of innovative metallurgical approaches were developed in the United Kingdom and Canada to increase tin grade and recovery, thus producing higher value concentrates in operations worldwide. These included:
- Improvement in primary and secondary gravity circuit feed classification
- Use of column flotation as the final (2nd) stage clean on tin flotation
- Use of Mozley multi-gravity separators as the final (2nd) stage clean on tin flotation
- Development of new flotation reagents
- Optimization of grinding circuits to ensure proper tin flotation kinetics
- Plant optimization especially pH and reagent delivery
AVAILABILITY
The expertise inherent in these advances can be accessed through SGS Minerals Services. With our detailed understanding of the critical controls to tin metallurgy, we can readily provide bankable cost-effective processing flowsheets or in-plant audits and optimizations.
Optimizing the flowsheet and reagent scheme in a mill can increase the tin flotation recovery by 20% (relative) and the overall plant recovery to 88-92%. Given that most plants operate at 85% recovery, this is a significant improvement.
Our programs pay close attention to:
- proper grinding to minimize overgrinding and the resulting production of slimes
- optimization of tin flotation kinetics which are dependant upon grain size
- pH during flotation
- suite of depressants and collectors
- variations in process mineralogy of each product
POTENTIAL APPLICATIONS
Development of conceptual flowsheets and pilot plant testing programs for new tin deposits or tin-rich zones of existing deposits - Optimization of existing traditional gravity/magnetic, multi-gravity and tin flotation flowsheets now in operation.
- Assessment of or modification to tin flotation reagent regimes.
- Addition of multi-gravity & tin flotation to existing traditional gravity plants during optimizations or expansions.
- Tailings re-treatment projects.
- Slag treatment for recovery of tin alloys.
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CASE HISTORIES
a) Effect of metallurgical improvements at the Wheal Jane concentrator treating ore from the South Crofty Mine, Cornwall
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Gravity % Recovery |
Tin Flotation, % Recovery |
Total % Recovery |
Final Concentrate Grade |
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| 1985 |
65% |
15% |
80% |
45% Sn |
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| 1997 |
72% |
18% |
90% |
60% Sn |
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b) Effect of optimizing regents and operating conditions Effect of direct tin flotation using sulphosuccinate collectors modified with fatty alcohol ester sulphate. In this case, the cassiterite concentrate was upgraded from 58.3% SnO2 to 91.2%, with rejection of 95% of the zircon. In addition, a columbite/tantalite concentrate was produced.
The important factors that controlled the flotation included the degree of collector modification, the type and amount of depressant and the flotation pH.
| Weight % |
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Assays % |
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% Distribution |
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SnO 2 |
Nb 2 O 5
Ta 2 O 5 |
ZrO 2 |
SnO 2 |
Nb 2 O 5
Ta 2 O 5 |
ZrO 2 |
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SnO 2 Cleaner
Conc 62.77 |
91.2 |
2.20 0.16 |
0.98 |
98.2 |
38.5 40.5 |
4.2 |
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Nb 2 O 5 /Ta 2
O 5 Mag Conc 5.36 |
3.10 |
37.3 2.39 |
4.10 |
0.3 |
55.5 51.2 |
1.5 |
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ZrO 2 Gravity
Tail 30.97 |
1.68 |
0.62 0.06 |
43.8 |
0.9 |
5.2 7.6 |
93.6 |
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| Slimes 0.90 |
40.5 |
2.80 0.20 |
10.2 |
0.6 |
0.8 0.7 |
0.7 |
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| Feed 100.00 |
58.3 |
3.60 0.25 |
14.5 |
100.0 |
100.0 100.0 |
100.0 |
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Data from Bulatovic and deSilvio, Minerals Engineering, 13, 871-879.
EXPERIENCE RECORD
| Client |
Deposit |
Location |
Elements |
Process |
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| Noranda |
Geco |
Canada |
Sn, Zn, Cu |
Tailings |
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| Rio Algom |
East
Kemptville |
Canada |
Sn, Cu, Zn |
HLS, Grind, Grav / Mag,Flot, |
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| Billiton Metals |
Mt. Pleasant |
Canada |
Sn, Zn,
WO3, In |
HLS,Grind, Grav / Mag, Flot |
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South Crofty
Ltd |
South Crofty |
UK |
Sn/WO3 |
Grav/Mag |
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Carnon
Consolidated
Ltd |
Wheal Jane |
UK |
Sn/Cu/
Zn/WO
3 /CaF 2 |
Grav/Mag, MGS/FLot |
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Carnon
Consolidated
Ltd |
Mt Wellington |
UK |
Sn/Cu/Zn |
Grav/Flot |
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Geevor
Mines Ltd |
Geevor |
UK |
Sn |
Grav |
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Renison
Bell Ltd |
Renison Bell |
Tasmania |
Sn |
Grav / MGS / Flot |
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Sunshine
Mining |
Pirquitas |
Argentina |
Sn, Ag, Zn |
Grind / Grav / Flot / Mag |
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| Paranapanema |
Mamore |
Brazil |
Sn, Ta,
Zr, Nb |
Flot |
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| Novosibirsk |
N/A |
Russia |
Sn |
Grav / Flot |
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| Thaisarco |
Smelter |
Thailand |
Sn |
Grav |
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| MINSUR |
San Rafael |
Peru |
Sn |
Grind, flot, |
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HLS = Heavy liquid separation, Grind = Grinding, Grav = Traditional Gravity,
MGS = Multi-Gravity Separator, Mag = Magnetic Separation, Flot = Froth Flotation.
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