What is the power required to crush 100 ton/h of limestone if 80 percent of the feed passes a 2-in. screen and 80 percent of the product 1/8-in. screen?

Question

What is the power required to crush 100 ton/h of limestone if 80 percent of the feed passes a 2-in. screen and 80 percent of the product [latex]\frac{1}{8}[/latex]-in. screen?

Accepted Answer

From Table 29.1, the work index for limestone is 12.74. Other quantities for substitution into Eq. (29.10) are

[latex]\frac{P}{\dot{m}}=0.3162 W_i\left(\frac{1}{\sqrt{D_{p b}}}-\frac{1}{\sqrt{D_{p a}}} ight)[/latex] (29.10)

[latex]\begin{gathered}\dot{m}=100 ext { ton } / h \D_{p a}=2 imes 25.4=50.8 \ mm \quad D_{p b}=0.125 imes 25.4=3.175 \ mm\end{gathered}[/latex]

The power required is

[latex]\begin{aligned}P & =100 imes 0.3162 imes 12.74\left(\frac{1}{\sqrt{3.175}}-\frac{1}{\sqrt{50.8}} ight) \& = ext{169.6 kW (227 hp )}\end{aligned}[/latex]

TABLE 29.1 Work indexes for dry crusbing† or wet grinding‡
Material	Specific gravity	Work index, $W_i$
Bauxite	2.20	8.78
Cement clinker	3.15	13.45
Cement raw material	2.67	10.51
Clay	2.51	6.30
Coal	1.4	13.00
Coke	1.31	15.13
Granite	2.66	15.13
Gravel	2.66	16.06
Gypsum rock	2.69	6.73
Iron ore (hematite)	3.53	12.84
Limestone	2.66	12.74
Phosphate rock	2.74	9.92
Quartz	2.65	13.57
Shale	2.63	15.87
Slate	2.57	14.30
Trap rock	2.87	19.32
† For dry grinding, multiply by $\frac{4}{3}$ . ‡ From Allis-Chalmers, Solids Processing Equipment Div., Appleton, Wisconsin, by permission.

Question 29.1: What is the power required to crush 100 ton/h of limestone i......

Related Answered Questions

Verified Answer: