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Top tips for producing quality aggregates

By using the right processing equipment, everybody can produce quality aggregates

Rubble Master makes it easy to achieve good quality aggregates. Whether processing concrete, asphalt or rock the Rubble Master range of machinery, available through Australian distributor Tricon Environmental, can help operators meet their spec with flow analysis and material testing.

The raw material and material management is as important as the aggregate crushing process. If the feed material is low quality, the finished product will also be of low quality. If good product is mixed with debris or there is no control over what recycled materials are coming in, it will be difficult to produce quality aggregates.

For sites that accept recycled materials it would be best practice to have separate dump sites for different materials and avoid mixing of stockpiles.

Next, it is crucial to differentiate deconstruction and demolition. The goal of demolition is to simply tear down a structure. On the other hand, deconstruction takes down a structure intending to salvage and separate materials to reuse and recycle them. If a feed cannot be controlled, it will need to be sorted before being processed.

Less dirt makes a cleaner end-product that sells better. If there is excessive dirt in the feed, it can slow down production and maximise wear. Pre-screening material segregates dirt and fines and gives the processor another product to sell.

Most mobile crushers feature a pre-screen to bypass fines or segregate fines via an optional side-discharge conveyor. If this is not sufficient, a mobile scalping screen can be used for a more efficient dirt segregation process.

Rubble Master impact crushers produce high quality aggregates, clean from residuals. A uniform product is a key characteristic of quality aggregates. The crusher type has a big influence on the shape and gradation of the product. Typically, if spec materials are required an impact crusher delivers a better gradation, a more cuboid aggregate shape and makes it easy to meet an engineered spec.

An impact crusher can achieve a better grade of material

In a concrete recycling application, removing rebar and tramp iron is paramount. Rubble Master’s machines include a self-cleaning magnetic separator that can be used to lift rebar out of the crushed material and discharge steel to the side. The magnet picks up the steel and the conveyor belt moves the rebar until it leaves the action area of the magnet.

Further, lightweight contaminants such as fabrics and wood chips are hard to get rid of. Many contractors use a labourer to pick trash from a finished pile. This is a dangerous and inefficient process because the labourer has to get close to the crushing action and can’t keep up with the crushing plant. A wind-sifter can be used to blow out a certain percentage of lightweight materials to get a cleaner end product.

A screen classifies the material by size and allows an operator to get remove oversize and undersized particles. The amount of screen decks within a screen defines how many products you can produce:

  • one deck = two products
  • two decks = three products
  • three decks = four products

Another important point is to correctly stockpile the end product. Building a layered stockpile with a constantly moving radial conveyor or moving the product with a dozer help reduce segregation eliminates the need to reblend the material before shipment. If the material is not stockpiled correctly, it could lead to the rejection of the material.

Some quality aggregate specs require a clean stone product. Washing materials helps you float out contaminants and wash fine particles off the rock. Rubble Master mobile incline screens can be fitted with a rinser kit, including plumbing and spray bars, to rinse your product for a cleaner end-product.

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