Primary crushing of run-of-mine (ROM) coal for domestic oven sizes: which machine is typically used first to reduce ROM coal to manageable size before further handling?

Introduction / Context:
ROM coal contains large, irregular lumps straight from the mine. Primary crushing is required to produce a manageable top size for downstream sizing or domestic use. Selecting the appropriate primary crusher affects throughput, product size distribution, and maintenance cost.

Given Data / Assumptions:

• Feed is ROM coal, large and heterogeneous.
• Objective is initial size reduction to a consistent, smaller top size.
• Subsequent steps (screening, secondary crushing) may follow as needed.

Concept / Approach:
Jaw crushers are classic primary crushers for hard/abrasive and large-lump feeds. Their compression mechanism between a fixed and a moving jaw produces a well-controlled primary product size suitable for further processing or direct sizing for domestic requirements.

Step-by-Step Solution:
Identify primary duty: breaking large ROM lumps.Match equipment: jaw crusher excels at primary compression crushing.Select “Jaw crusher” over mills or secondary-type crushers for the first stage.

Verification / Alternative check:
Plant flowsheets and quarry operations routinely specify jaw crushers ahead of screens and secondary crushers for initial size reduction of mined material, including coal where suitable.

Why Other Options Are Wrong:
Hammer crusher: typically secondary/tertiary for brittle materials at smaller feed sizes.Ball/tube mills: grinding equipment, not primary crushers for ROM lumps.

Common Pitfalls:
Feeding a hammer crusher directly with very large ROM lumps can cause rapid wear, blockages, and poor control of product size compared to a jaw crusher primary stage.

Final Answer:
Jaw crusher