When shopping for a road-portable concrete recycling system, consider the equipment's efficiency, mobility, durability and maintenance. These key factors determine the price/quality quotient and profit/payback expectations for each system in your operation and market.
Because profitability relies on low equipment downtime, it is important to know the manufacturer's track record, watch the equipment in action and talk with current customers before buying.
Avoid the "one plant does everything" syndrome. Make sure the manufacturer can provide what you need; don't let it try to sell you just what it has available. Although a customized plant might cost a little extra money, in the long term, it can pay for itself many times over.
The crusher should be a primary impactor designed for recycling. Recycling impactors have a reduction ratio of as much as 30-to-1 in a closed circuit, are faster and give more control over product size than jaw crushers. They are built to crush materials that contain wire mesh, reinforcing rods, dowel pins and other steel items.
A powerful electromagnet should be mounted on top of the discharge conveyor to pull steel from the crushed materials. To ensure efficient material flow, the magnet should be positioned in line with the discharge conveyor.
If you plan to crush construction and demolition debris, you may not want to pulverize the feed. Pulverized materials make downstream separation more difficult, and pulverizing wood tends to contaminate the smaller products.
Your system should include options such as picking stations to remove certain loose materials and an air classifier for wood and paper removal.
Some road-portable systems - including crushing plants, discharge conveyors, screen plants and return conveyors - can be set up in less than a day without crane assistance. Key elements to a fast set-up are a skid-on hopper and independent hydraulic legs - not jacks - that provide solid support with infinite, accurate height adjustment.
The system's supplier can help you determine the optimum size of the crushing plant and system components based on your material mix, tons per hour requirements and other needs. An oversized plant can be wasteful in terms of the initial cost and, to a lesser extent, the operating cost. An undersized plant can be a disaster in terms of excessive feed preparation, inadequate production capacity, high downtime and lost profits.
A well-engineered recycling system should operate efficiently for many years with minimum maintenance. Compare each manufacturer's maintenance recommendations carefully and make sure wear parts will be easy to replace. For example, a hydraulically operated split housing on the impactor will save hours of downtime in replacing wear parts such as blow bars.
Electrical control systems range from manual, push-button types to automated, computerized types. Any system you purchase should meet Occupational Safety and Health standards, and, for safety and efficiency, you should be able to control the entire recycling system from the operator's station. The system also should have quick-disconnect fittings for fast, accurate assembly.
The equipment supplier should be available for the system's set-up, training and start-up, and should provide a good operation and maintenance manual written specifically for your system.
Finally, remember that experience is everything. Ask how many systems the manufacturer has built and how many are still in operation. Be extremely wary of any manufacturer that must be coaxed to give you a list of customer contacts.
The Construction Materials Recycling Association (CMRA), a non-profit, education trade group, provides its members with a compre- hensive list of literature and other information on recycled construction materials and represents members at trade shows and seminars.
The CMRA provided comments to the U.S. Environmental Protection Agency regarding its recent construction waste and demolition debris (C&D) recycling waste characterization study. The association currently is trying to find ways to develop more markets for recycled C&D waste.
For more information, contact the CMRA at P.O. Box 644, Lisle, Ill. 60532. Phone: (630) 548-4510. Fax: (630) 548-4511. E-mail: [email protected]