Moving Materials

A new moving floor conveying system promises to increase the flexibility and efficiency of material handling operations



Effective material handling management is more than simply transporting goods from point A to point B. Moving bulk materials from one point to another creates logistical challenges at every step in the ceramic manufacturing process. Additionally, each product often presents its own unique material handling challenges, including bridging and plugging problems, extreme abrasiveness, or inconsistent flow. Choosing the correct material handling system for the product can mean the difference between poor plant performance and maximum efficiency.

One trend steadily gaining popularity in material handling operations is the use of moving floor conveying systems to streamline material movement. These systems can be adapted for storing, conveying and feeding nearly any material, thereby providing a flexible solution to complex material handling requirements.

How It Works

The foundation of the moving floor system is a series of hydraulically actuated floor slats and a drive unit. The drive unit powers the slats through a four-phase cycle to convey the material (see Figure 1). In each of the first three cycles, one-third of the slats move while the remaining two-thirds remain in place. In the final cycle, all slats move together to convey the load. While in motion, the floor slats remain horizontal, moving in a forward-to-backward stroke.

The slats, which are composed of aluminum or formed steel, extend the length of a trailer or bunker floor. Floor slats ride on low-friction bearings that are fastened to a sub-deck. On most systems, both in stationary and mobile applications, the drive unit is mounted beneath the floor for easy access. Slats are attached to the drive unit's cross-drives; hydraulic cylinders move the cross-drives, which in turn move the floor slats. Power to the drive unit is provided by a tractor-mounted power take-off and hydraulic pump, or by a hydraulic power unit.

Because of their design, moving floor systems offer several advantages over conventional systems when conveying bulk materials. For example, they can be constructed to support virtually unlimited tonnage, making them ideal for heavy or dense products. They can also operate at variable speeds, which is important when a regulated flow of material is needed, such as when sending material to a crusher (to avoid overloading the equipment) or when metering products for batch mixing.

The V-Shaped Advantage

Moving floor systems have been used in the waste and recycling industries for decades and have been designed to handle a moderate amount of abrasion. However, a conventional moving floor conveyor cannot withstand the extreme, daily wear of products like sand, aggregate and other highly abrasive materials that are often found in the ceramic industry.

Recently, a new system* has been developed that provides plant engineers with the benefits of an efficient, flexible moving floor system in a durable design that can withstand even highly abrasive loads. The system is constructed of formed steel and features V-shaped slats. These slats are designed for high-impact use, and their durability allows them to absorb increased load impact and abrasion. The configurations of each bunker vary, and systems are designed to a plant's specific requirements; however, as with other moving floor systems, dimension and weight restrictions are virtually unlimited.

The system provides a viable solution to a number of bulk handling problems and can boost plant efficiency by increasing throughput and flexibility, reducing downtime, and lowering power requirements.

Enhanced Functionality

Specialized bunkers are designed to both store and convey material, maximizing plant floor space. The system can also be constructed to include multiple bins or walls for applications in which several different materials need to be stored separately to maintain product uniformity, yet will ultimately be delivered to the same location for processing. Each bin contains a separate moving floor system that meters the material to a take-away conveyor.

For reduced dust emissions, roofing can be added. Systems can also be flush mounted, installed above ground, placed in a pit or secured to an existing pad, depending on the plant's material handling needs.

Moving floor systems also provide the flexibility to move several different products with the same conveyor. Unlike a belt conveyor, a moving floor system can handle both light and extremely dense materials; unlike a screw conveyor, a moving floor system can meter products of almost any size-from fine materials to large rocks and boulders. Mobile systems are also available for applications in which material must be loaded or unloaded at various locations.

Cost Saving Capabilities

While many conventional conveying systems require increased power at start-up, moving floor conveyors do not have this requirement. As a result, they help reduce energy costs while having the ability to dislodge material blockages and move loads weighing up to several hundred tons.

Stationary moving floor conveyors offer other benefits that many other material handing systems cannot. Since the moving parts on the systems are limited to the hydraulic drive unit, maintenance requirements are low. Additionally, because there are no dangerous pinch points, employees can walk on a moving floor system even while it is in motion. When used properly, moving floor systems are much safer than many other conveying mechanisms.

Equipment Integration

Although moving floor systems are often used in place of traditional conveying equipment, such as belt conveyors, screw conveyors or bucket elevators, they can also be used with existing equipment to provide multiple options for storing and routing incoming materials. Bi-directional moving floor systems allow for the loading or unloading of material from either end, and speed control ensures easy integration of a plant's material handling operations.

For plants using front-end loaders to transport their materials to various locations, equipment overload is a common problem. Operators have minimal control over how much material is pushed or dropped onto bulk handling equipment, which leads to costly repairs and downtime. With a moving floor conveyor, variable speed control enables the system to index material to other equipment at a regulated rate.

Efficiently handling heavy, bulky materials is another challenge frequently encountered in ceramic manufacturing plants. One option is to engage a loader for long periods of time to slowly feed a conveyor. Most commonly, however, loaders are used to dump full bucket loads of material onto the conveyor all at once. This often causes undo stress on the conveying system and the trommel, which results in high maintenance costs and lowered productivity.

A moving floor conveyor with V-shaped slats alleviates some of these problems because it is specifically designed to absorb higher impact and abrasion. This feature allows the system to be loaded to capacity and to continuously feed material to a take-away conveyor. Unnecessary wear on the take-away conveyor and other sorting equipment is also reduced because the machinery is supplied with a consistent, but not excessive, flow of material.

A Flexible Solution

Over the past several decades, moving floor systems have become increasingly popular in a number of different industries for their ability to enhance the flexibility and efficiency of material handling operations. Today, with systems designed specifically for highly abrasive products, ceramic manufacturers can benefit from this technology as well.

For more information about flexible material handling systems, contact KEITH Mfg. Co., 401 N.W. Adler St., Madras, OR 97741; (541) 475-3802; fax (541) 475-2169; e-mail sales@keithwalkingfloor.com ; or visit http://www.keithwalkingfloor.com .

*The KEITH^® Walking Floor^® V-Floor^TM system, supplied by KEITH Mfg. Co., Madras, Ore.