Log Washer

The CONSTMACH Log Washer is a heavy-duty aggregate scrubbing machine designed for the most heavily contaminated feed materials, where standard sand washers cannot break down bonded clay and silt. It belongs to the Gravel Washing Systems product group and is used wherever gravel, crushed stone, or run-of-mine aggregate arrives with a high content of plastic clay, loam, or other sticky impurities that must be removed before the material can be used in concrete, asphalt, road base, or other engineered applications.

The machine is built around two parallel shafts fitted with hardened paddles, arranged in a long inclined trough. The shafts counter-rotate, and the paddles are set on a helical pattern so that material is both lifted and conveyed up the incline while being continuously turned over. This combination produces an intense scrubbing action: aggregate particles are forced against one another and against the paddles, and the resulting abrasion strips clay and silt coatings from the stone. Because the cleaning relies on stone-on-stone attrition rather than only on water pressure, the Log Washer is effective on tightly bonded, plastic contaminants that resist conventional washing.

Water is introduced into the trough to carry away the liberated fines. As the paddles drive the cleaned aggregate up the incline toward the discharge end, the slurry of clay, silt, and wash water overflows at the lower end and is directed to the downstream water-treatment or settling stage. The clean, coarse aggregate exits at the top, ready for screening, further washing, or stockpiling. The angle of installation and the rotational speed of the shafts can be adjusted to suit the type and severity of contamination, allowing operators to balance retention time, throughput, and cleaning intensity.

The CONSTMACH Log Washer accepts feed material up to 50 mm in size and is suited to gravel, crushed stone, and similar aggregates with high clay or loam content. Typical applications include sand and gravel pits, quarries, and mineral processing and recycling operations where dirty feed would otherwise compromise product quality. In mining contexts, the same scrubbing principle is used to liberate valuable minerals locked within clay.

The standard configuration offers a throughput in the range of approximately 200 to 400 tons per hour, making it a high-capacity unit positioned at the front of a washing circuit. It is powered by two electric motors and runs at a controlled shaft speed in the order of 15 to 25 rpm, low enough to maximise scrubbing contact time while protecting the wear components. The unit is engineered for continuous operation under abrasive conditions, with a robust steel main body and wear-resistant paddle facings.

Key components reflect the demanding duty: a welded steel trough forms the main body, the shafts are produced from chromium-nickel-molybdenum alloy steel, the paddles and helices are protected with abrasion-resistant facing, and the drive line runs on heavy-duty spherical roller bearings in cast steel housings. Replaceable wear parts and a low operating speed are intended to extend service life and reduce downtime in continuous washing plants.

Within a complete washing system, the Log Washer typically operates as the primary scrubbing stage, ahead of vibrating screens, sand washers, and water-clarification equipment. By removing the bulk of the clay and silt at the inlet, it protects downstream equipment, improves the efficiency of subsequent washing and grading, and helps ensure that the finished aggregate meets cleanliness requirements for construction use.