how to calculate jaw crusher power kw

Calculating the power requirement (in kW) for a jaw crusher involves understanding the crusher’s operational parameters and material properties. The power needed depends on factors like feed size, product size, capacity, and the hardness of the material being crushed.

Common Methods to Calculate Jaw Crusher Power (kW):

# 1. Empirical Formula (Bond’s Equation)
Bond’s Law is widely used to estimate crusher power consumption:

\[
P = \frac{W_i \times C \times (F_{80} – P_{80})}{\eta}
\]

Where:
– \( P \) = Power (kW)
– \( W_i \) = Bond Work Index (kWh/ton) – a measure of material hardness
– \( C \) = Feed rate (ton/h)
– \( F_{80} \) = 80% passing size of feed (µm)
– \( P_{80} \) = 80% passing size of product (µm)
– \( \eta \) = Efficiency factor (~0.5–0.7 for jaw crushers)

# 2. Hersam’s Formula
A simplified version for jaw crushers:

\[
P = 0.01195 \times L \times W \times s \times n
\]

Where:
– \( L \) = Length of feed opening (cm)
– \( W \) = Width of feed opening (cm)
– \( s \) = Closed-side setting (cm)
– \( n \) = Speed of rotation (rpm)

# 3. Manufacturer’s Data & Practical Approach
Many manufacturers provide power ratings based on:
– Motor Power: Typically, jaw crushers have motors ranging from 15 kW to 500 kW, depending on size and capacity.
– Crushing Force: Higher crushing force requires more er.
– Throughput Capacity: Higher tonnage requires higher power.

Example Calculation:
Given:
– Feed rate (\( C \)) = 100 ton/h
– Bond Work Index (\( W_i \)) = 12 kWh/ton
– Feed size (\( F_{80} \)) = 250 mm → 250,000 µm
– Product size (\( P_{80} \)) = 50 mm → 50,000 µm
– Efficiency (\( \eta \)) = 0.6

Using Bond’s Equation:
\[
P = \frac{12 \times 100 \times (250000 – 50000)}{0.6}