Ceramic Industry

SPECIAL SECTION/BRICK & CLAY RECORD: Crushing Abrasive Materials

February 1, 2012
Selecting the right size reduction equipment will help improve product quality and reduce operating costs.

Test plants help quantify customers’ unique size reduction needs.


Manufacturers in the brick, ceramic and glass industries have to deal with notoriously difficult challenges in material size reduction. What makes glass and ceramics tough, durable products presents difficulties during the preparation of raw materials. Recycling process scrap and end-of-life disposal are important in considering the size reduction requirements.

The basics of size reduction are simple. Size reduction is simply putting energy into material to make large pieces smaller. Hundreds of machines-ranging from simple to complex-exist to accomplish this objective in many industries and for many materials. A variety of machinery choices are available simply because one size does not fit all. Selecting the best type of equipment for your process will affect plant profitability.

Evaluating Size Reduction Needs

Five basic questions should be asked to begin an evaluation of a size reduction process. If you begin your project by defining these variables, you will be off to a good start:
  • What is the material to be crushed?
  • What is the size range of the feed to the crushing machine?
  • What is the desired production rate (Kg/HR, TPH, PPH)?
  • What is the moisture range of the raw material?
  • What is the size range desired of the material after crushing?
It is important to find a good partner with a broad range of size reduction expertise. The best suppliers will provide the following: a variety of size reduction machine types; a full-service test plant and toll crushing capability; after-the-sale field service; a good understanding of the size reduction processes’ ability to influence the whole process; and a commitment to the industry.

Machine Types

Companies that offer a limited size reduction product range (i.e., only one or two types) will logically be more limited in the solutions they can provide. The temptation exists to offer sub- optimal solutions by stretching to meet size reduction processing objectives.

For example, maximum feed size can limit machinery selection and applicability. Most machines are limited by the largest feed accepted. A larger machine or a different machine style altogether may have to be selected to accommodate bigger pieces in the raw material feed stream vs. the tonnage determining the machine style needed.

Reduction ratios vary by machinery type, so this can be another area where a manufacturer can be led astray. For instance, if a glass recycler wants to crush to an intermediate fine product, machines can be selected with reduction ratios of:
  • 2:1-roll crusher, jaw crusher
  • 10:1-vertical shaft impactors
  • 20:1-cage mills, hammermills
  • 200:1-ball mills
Which piece of equipment should be used? Until the five questions listed above are answered and the entire process is understood, the answer will not be clear. Testing your material is the best way to proceed in your evaluation.

The choice of size reduction equipment impacts more than just particle size. Other factors affected by the size reduction process may not be as obvious, but they can have significance. For instance, additional factors can include:
  • Ability to use one machine vs. two or three
  • Operating costs vs. acquisition cost tradeoffs
  • Particle shape and the effect on product quality
  • Particle shape and the effect on operating costs
  • Total energy required for a system


Testing and Toll Crushing

The best size reduction equipment companies operate test plants. Each year, these facilities help quantify the unique size reductions that customers need. Some North American companies have continuously operated test facilities for over 80 years and continue to test for over 100 customers a year. This service will always be in demand due to unique customer requirements.

Testing provides data on a core material processing step-size reduction-and helps to quantify the cost of ownership for the equipment. For a nominal testing fee, producers can tap into the size reduction equipment manufacturer’s knowledge base.

Testing produces information on the following:
  • Pre-processing and post-crushing particle size distribution
  • Moisture
  • Power consumption per unit processed (e.g., KW/MT)
  • Wear cost estimate due to metal replacement parts
  • Machinery selection confirmation
Toll crushing is a service for a fee. Toll crushing customers include those undergoing new product development or process improvement/development. Toll crushing customers are also those companies that have an intermittent need for crushed materials (e.g., sending material quarterly for crushing) or have limited capital to purchase equipment.

Toll crushing can allow a relationship to develop between companies before the end user invests capital in buying equipment. In the proper circumstances, toll crushing can be a valuable, worthwhile service.

After-the-Sale Service

Plant personnel with size reduction equipment should ask themselves: “When did I last see someone from the crusher manufacturer?” If you don’t know or can answer “never” to this question, how good is your size reduction business partner?

Factory-trained service and parts sales personnel are part of the value proposition for your equipment selection process. Staying engaged with the crusher manufacturer will help maintain profitability by having professional advice available to keep the crushing systems running in good order. In addition, as machine designs and features are introduced, knowing the original equipment manufacturer helps plant process and maintenance stakeholders evaluate new features that can improve output, lower operating costs, or improve product quality.

Application Example

Brick plant grinding rooms prepare clays, shales and scrap brick for blending and, ultimately, thermal processing in kilns to produce residential- and commercial-grade brick. Historically, grinding was achieved in three size reduction machines.

New features were introduced by a company that solved several problems that are pervasive in ceramic raw material preparation:
  • High-moisture raw materials
  • High-plasticity materials
  • Abrasive
  • Large feed size
  • Need for a consistent particle size distribution after crushing
  • Improved particle shape properties
Producers in the brick industry quickly adopted the new technology and realized a step-change decrease in material preparation operating costs. Quantifiable benefits include:
  • Ability to eliminate two crushing machines and related material handling equipment from the process, thereby lowering cost of ownership
  • Consistent output production rates with varying moisture of incoming raw material
  • Consistent output particle size
  • Reduction in extruder power consumption due to improved particle shape
  • Increase in extruder die life due to improved particle shape
  • Significant reduction in direct costs due to wear parts
  • Reduction in maintenance and repair costs


Industry Commitment

Is your size reduction equipment manufacturer dabbling in your industry or are they committed to your industry? Well-maintained crushers should be expected to last 20-30 years. A healthy business partner will belong to and be active in your industry trade association, develop products and features to help solve industry problems, maintain a current website on their products and services, and exhibit at industry trade shows.

Taking a step back when evaluating your choices in size reduction and consideration of these points may help guide you in the best direction objectively. You will want your partner to be there when you need them.

Conclusion

Don’t ignore the importance size reduction has on profitability and product quality. Take time to objectively evaluate the systems, equipment, and personnel needed to crush, screen, convey, and store your raw materials. You may be surprised at the improvement opportunities that exist in your plant.

For more information, contact Stedman at 129 Franklin St., Aurora, IN 47001; call (800) 262-5401 or (812) 926-0038; fax (812) 926-3482; email sales@stedman-machine.com; or visit www.stedman-machine.com..

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