Coal Preparation » Gravity Separation
The objectives of this project were to:
- Compare the performance of shortened spirals with conventional spirals.
- Identify any areas of reduced metallurgical performance in the shortened spirals.
- Determine whether two stage spirals offer any significant metallurgical advantage.
Despite the experimental difficulties associated with conducting in plant testwork, tests were conducted which enabled a comparison of shortened and conventional spirals.
Tarong Coal Preparation Plant operates spirals to produce a high ash product; the spirals are operated at high throughputs and solids loadings. This makes it difficult to analyse the impact of short spirals under more normal operating conditions.
The data from 20 tests were evaluated and seven tests which showed consistent mass balances were float sink analysed.
Duplicate tests, conducted at different times, demonstrated that the derived data were of acceptable accuracy.
Tests conducted on 2, 3 and 4 turn spirals indicated that the yield and ADR decrease with increasing spirals length. This was shown to be due to the size by size cutpoint and Ep decreasing with increasing spiral length.
Tests conducted on a compound 2-3 turn spiral were significantly less efficient than tests conducted under similar conditions on a conventional 4 turn spiral. No explanation can be offered for this effect.