Question

A copper ore containing 4.3 wt% water, 10.3 wt% CuSO, and 85.3 wt% rock is fed to a staged counter current extractor at a rate of 11.7 tons per hour. We wish to recover 98% of the copper sulfate using pure water as the fresh solvent. The solution produced is to be 10 wt% copper sulfate and 90 wt% water. If after each stage 1 ton of inert rock retains 2 tons of water plus the dissolved copper sulfate, how many stages are required?

Answer 1

6 stages

Step-by-step explanation:

Given:

Copper ore contains:

4.3 wt% water

10.3 wt% CuSO₄

85.3 wt% rock

Feed rate = 11.7 tons per hour

solution produced is to be 10 wt% copper sulfate

90 wt% water

Now,

The CuSO₄ supplied through the feed = 10.3 wt% CuSO₄ × Feed rate

= 0.103 × 11.7

= 1.2051 tons per hour

also,

At each stage 2 tons of solution is collected

therefore,

The CuSO₄ collected in each stage

= weight of solution × 10 wt% copper sulfate

= 2 tons per hour × 0.1

= 0.2 tons per hour

also,

98% of the CuSO₄ is to be recovered

thus,

the amount of CuSO₄ to be recovered

= 0.98 × CuSO₄ supplied through the feed

= 0.98 × 1.2051 tons per hour

= 1.180998

Therefore,

The number of stages required =
`\frac{\textup{amount of CuSO₄ to be recovered }}{\textup{CuSO₄ collected in each stage }}`

=
`\frac{\textup{1.180998}}{\textup{0.2}}`

= 5.90499 ≈ 6 stages