Concrete batch plants have changed significantly over the last 20-30 years in terms of technology, efficiency, speed and lower maintenance. If your plant is showing its age, consider investing in new equipment.
The role our company plays in specifying, installing, troubleshooting, repairing and upgrading ready mix or precast concrete plants provides a unique opportunity to see what works and what doesn’t when it comes to batch plant efficiency. I’d like to share five principles we have observed that always seem to lead to more efficient, and therefore more profitable operations. A simple definition of concrete plant efficiency is the ratio of (a): the cost of inputs (employee hours, materials, energy, equipment, etc.) to (b): the revenue generated by sales. In other words; the lower your costs and the higher your revenue, the greater your efficiency. The most efficient concrete plants produce more concrete with less wasted material, lower repair costs, less downtime, and fewer disruptions in employee productivity. How to achieve this efficiency is the $64,000 question that we’ll elaborate on in this post.
1 Preventive Maintenance
At concrete plants where some type of formalized inspection and maintenance schedule is in place, there tend to be fewer breakdowns. If the plant manager recognizes the importance of regular PM and communicates that to employees, chances are good that noisy bearings, worn belts, leaky air systems, clogged filter bags, etc., will be detected and repaired before breakdowns interrupt the concrete batching process. Also…Stock critical plant parts such as solenoid valves, air cylinders, bearings, and various repair kits. If you aren’t sure what spares are on hand, sit with your maintenance person and put together a list. If you need help compiling a list, Contact Mid Atlantic Concrete Equipment and we’ll be glad to suggest one based on your specific concrete plant and equipment.
Keep your concrete plant parts area neat and put labels on shelves. Have v-belts organized for easy access. Tip: If you have to use high pressure air to aerate your cementitious material, a refrigerant or desiccant air dryer will increase your filter bag change interval. A low pressure – high volume blower will all but eliminate moisture or over-pressurization of air pads and is the preferred method of fluidizing material. Finally, consider PM software, either stand-alone or offered as part of your batching software. It provides a great way to track parts and equipment, and can help with spotting failure trends and recovering warranty reimbursements to which you are entitled.
Keeping a concrete plant clean is a constant battle, but one well worth winning. Abrasive dust is especially hard on solenoid valves and cylinders. Add to that a little moisture, which mixes with the dust to form a crust that’s hard to remove, and you have a mess that hinders maintenance and inspection activities. The obvious solution is a truck-loading dust collector. Not only does it keep the plant cleaner, but it allows truck drivers to spend less time washing down the truck after loading. If you want to dominate your market, reduce truck and plant cleanup, increase mixer barrel life by as much as 65% and significantly reduce your concrete plant maintenance, consider adding a central mixer to your concrete plant.
A central mixer will significantly extend truck drum life, all but eliminate dust issues, dramatically improve concrete consistency and quality and allow you to dominate your market.
Another thing that can save time is a drive-through truck wash system. Whether you purchase one from an established truck-wash vendor or build your own, these systems can boost plant efficiency. One operator in Maryland built an automated system equipped with an electric eye that starts a pump when the beam is broken, pushing water through plastic pipe with strategically-placed holes drilled throughout.
3 Batch Control
Out of all the processes in a concrete plant, the one most critical to overall speed is control of the batching process, as it affects the speed of the ribbon discharge into the truck. There are many different ways to sequence the materials—water, aggregate, cement, sand—but the crucial issue is to find the optimal discharge speed, somewhere below the point where the truck chokes up. In addition to the obvious benefits of avoiding stoppage of the batch process, proper ribboning of the materials into the mixer will shorten the drivers’ time to assure that the batch is properly mixed and adjusted for slump.
Efficient batching starts with having the right man in the seat. Customer service skills, phone etiquette and sales techniques are critical to concrete plant profitability.
Of course, the concrete plant has choke points as well, such as the hopper at the end of a conveyor. Monitoring choke points with a video camera has become standard practice at many plants, due to falling camera system prices, the ease of wiring Cat 5 cable, and the high resolution of the latest cameras. There is another way, probably more important, in which your drivers impact plant efficiency. This and related issues are discussed next.
4 Delivery Professional Staging
A frequent complaint of concrete plant operators is, “We could get more trucks through here if we knew where our delivery professionals were.” Delivery Professionals naturally like to take a break from the confines of a cab, but wasting time tracking them down wreaks havoc on plant efficiency. Multiply five minutes by 20 delivery professionals, and you can easily lose over an hour a day this way. Education and policy enforcement are central to minimizing these losses.
In addition, many concrete plant operators have installed pneumatic ticket delivery systems or paperless ticket systems that send ticket information via wi-fi to the truck cab as part of an overall solution. Remote ticketing systems have the added benefit of helping to keep delivery professionals out of the control room, something that is among the fondest wishes of many ready mix plant operators. Additionally, when designing a new Central mix or transit mix batch plant, consider including a driver lounge area located remotely from the control room.
5 Safety and Accessibility
Concrete batch plant designers must make cost-effective equipment selections. But when specifying safety features, keep the big picture in mind. Employees working around conveyors, agg gates and electrical panels are exposed to potential injury, which translates to exposure for the plant operator—to downtime as well as legal liability. Safety features that should be found at every plant include emergency pull-cord shutoffs and safety disconnects on conveyor and turn head motors, and confined entry access manholes in aggregate and cement bin compartments. Where possible, stairs with handrails are preferred over ladders.
Four letters: OSHA… They would have a field day with this little ditty. Aside from that it’s a good indicator of other processes and or conditions around this particular plant. Our guess is that this plant has a boat load of other issues.
Going one step further, certain kinds of automation can keep workers out of harm’s way. One example is a central grease manifold, which reduces employee exposure to dangerous areas by eliminating the need to apply grease at the bearing. Video observation systems provide a similar safety benefit by letting employees monitor choke points from the control room. Batch plant operators wanting to take further steps toward safety should review OSHA’s Lockout/Tagout (LOTO) standard, which protect employees from injury due to unexpected startup while cleaning or maintaining equipment.
Go to www.osha.gov and search on LOTO. You’ll find a great deal of information, including a tutorial and case studies that provide specific examples.
While it might be overly optimistic to think that you could eliminate breakdowns, following these 5 recommendations can and will go a long way to lowering operational and repair costs which can significantly reduce unplanned repairs that wreak havoc on plants, personnel and customers.