Question:

Copper ore assaying 10 wt.% Cu is fed to a concentration plant at the rate of 100 tons/h. If the grades of concentrate and tailing are 30 wt.% Cu and 1 wt.% Cu, respectively, the percentage recovery of copper in concentrate is ................... (round off to nearest integer).
Given: 1 ton = 1000 kg

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The recovery formula \( R = \frac{c(f-t)}{f(c-t)} \times 100% \) is a very useful shortcut for two-product separation problems. It allows you to calculate the recovery directly from the grade assays without needing to know the mass flow rates.
Updated On: Aug 31, 2025
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Solution and Explanation

Step 1: Understanding the Concept:
This is a material balance problem in mineral processing. Recovery is the percentage of the valuable metal in the feed that is successfully recovered into the concentrate product. It can be calculated using the grades (metal content percentages) of the feed, concentrate, and tailing streams.
Step 2: Key Formula or Approach:
Let F, C, and T be the mass flow rates of the feed, concentrate, and tailing, respectively. Let f, c, and t be their respective copper grades (as mass fractions).
The recovery (R) is defined as: \[ R = \frac{\text{Mass of Cu in Concentrate}}{\text{Mass of Cu in Feed}} \times 100% = \frac{C \times c}{F \times f} \times 100% \] We can find the ratio \(C/F\) from a copper balance: \(Ff = Cc + Tt\). Since \(F = C+T\), we get the two-product formula: \( \frac{C}{F} = \frac{f-t}{c-t} \). Substituting this into the recovery formula gives a direct equation for recovery based on grades: \[ R = \frac{c(f-t)}{f(c-t)} \times 100% \] Step 3: Detailed Calculation:
Given values:
- Feed grade, \(f = 10% = 0.10\)
- Concentrate grade, \(c = 30% = 0.30\)
- Tailing grade, \(t = 1% = 0.01\)
Substitute these values into the recovery formula: \[ R = \frac{0.30 \times (0.10 - 0.01)}{0.10 \times (0.30 - 0.01)} \times 100% \] \[ R = \frac{0.30 \times 0.09}{0.10 \times 0.29} \times 100% \] \[ R = \frac{0.027}{0.029} \times 100% \] \[ R \approx 0.93103 \times 100% = 93.103% \] Rounding to the nearest integer, the recovery is 93%.
Step 4: Final Answer:
The percentage recovery of copper is 93.
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