Raw Material Pretreatment for Fired Brick 
FAQ on Equipment Selection for Clay Crushing and Impurity Removal

Q1: Why should special attention be paid to clay crushing and impurity removal in fired brick production?

A: Clay often contains impurities such as rock fragments, small stones, and shells, which directly reduce green brick strength and finished product appearance quality. Proper selection of crushing and impurity removal equipment not only ensures continuous production by quickly removing debris, but also adapts to various particle sizes of impurities. It is a key step in stabilizing product quality.

Q2: What scenarios are suitable for the standard double‑roll crusher (two smooth rolls)? What are common issues?

A: This is the most commonly used equipment in domestic brick plants, available in various sizes (e.g., Φ500×500, Φ700×500). It relies on two smooth rolls rotating in opposite directions to squeeze the material; the roll gap determines the output fineness. However, in practice, many plants set the gap too large (over 5 mm, even up to 50 mm), greatly reducing crushing efficiency. It is suitable for coarse crushing where fineness requirements are low. For fine crushing, the gap must be strictly controlled and complemented by subsequent processes.

Q3: How does the spiral stone‑removing roll crusher remove stones? What are its limitations?

A: It consists of one smooth roll and one spiral roll. Stones are pushed out of the machine by the spiral rotation. However, when the raw material moisture content is high, stones become coated with clay and are harder to separate, reducing the removal efficiency, and small stones are difficult to eliminate. An improved version uses a smooth roll + a grooved roll (rectangular or triangular grooves) with a speed ratio of 1.2:1. Large stones are discharged laterally along the grooves, while small stones and clay are crushed in the gap. Recommended coarse crushing gap: 8–12 mm; fine crushing gap: 2–5 mm, with the two stages used together for better results.

Q4: What are the unique advantages of the toothed‑roll crusher?

A: Both rolls are equipped with coarse teeth that intermesh alternately; the discharge particle size is controlled by the roll gap. It is specifically designed for coarse crushing of sticky clay (plasticity index ≥15), effectively avoiding the large clay flakes that ordinary roll crushers tend to produce. It is especially suitable for crushing large clay lumps fed by scraper loaders, with a far superior crushing effect than conventional roll crushers.

Q5: What materials does the crushing roll crusher (with irregular teeth) primarily handle? How efficient is it?

A: This machine consists of a smooth roll and a roll with irregular teeth welded on the surface. It is mainly used for crushing semi‑hard materials (e.g., brick lumps, hard clay lumps), with an effective crushing rate of about 96% and uniform output. Since the two rolls are not equipped with limit springs, the crushing force is strong, making it more efficient for loose materials.

Q6: What are the characteristics of the stone‑removing roll crusher (ring‑type trapezoidal grooved toothed roll)?

A: Both rolls are of ring‑type construction with trapezoidal grooves and protruding teeth, and the teeth of the two rolls are staggered. It excels at crushing quarry stones, hard clay lumps, and other impurities with good efficiency. When paired with a fine‑crushing roll crusher, the entire raw material processing can reach an ideal level.

Q7: What is the most fundamental principle in equipment selection for different raw materials?

A: Raw materials vary greatly in plasticity, moisture content, impurity types, and particle sizes across regions – there is no "universal" equipment. Selection must be based on your specific raw material characteristics, process requirements, and production capacity. Choose the appropriate equipment type and combination (e.g., coarse + fine crushing), and strictly control parameters such as roll gaps, in order to achieve high quality and high output.