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As a rule, minerals and other materials must normally be reduced in size in order to handle and process them.  Size reduction is obtained using various forms of crushers, breakers or sizers, depending on the industry and the applications.  These can include rock, ores, coal, glass cullet and a host of other minerals and materials, including recycled products.

Among the more commonly employed and heavily used equipment are granulators (ring hammermills), jaw crushers and hammermills. All such equipment is equipped to take a great pounding and to last for years, often for many generations. Just remember that, while a crusher might crush hundreds of tons per day with seemingly little effort, in fact, each and every ounce of material creates some degree of wear and strain. The trick is to know how to recognize when the cumulative wear begins to require attention, so that a developing issue is addressed before it turns into a major event.

In a time when maintenance staffs have been reduced and a company of necessity must rely on outside contractors, it’s useful to understand that, even with a limited maintenance staff, a company can employ some basic diagnostics that can keep their investment in size reduction equipment out of harm’s way. Here’s an overview of what can be done with ring hammers (granulators). In following posts I’ll cover jaw crushers and reversible hammermills.

Ring hammermills shouldn’t shake, rattle & roll

Granulators, or ring hammermills, are composed of a shaft/hammer/disc assembly rotating at medium speed (300-720 rpm depending on diameter) within a breaker cage. Before your granulator was fully assembled, the folks in our factory balanced the rotor assembly on a static balance stand. But after extended service, the effects of wear on these things can cause problems such as vibration, hot bearings and unusual wear.

If hammers are allowed to wear beyond their point of normal replacement, they can break and cause a serious vibration. Be sure to check the condition of all wear parts regularly, especially the rotating parts.

Another condition that can cause vibration is improper feeding. The best way to feed a granulator is to slide the material into the crusher along the breaker plate, and to avoid dropping material directly on the rotor. When the crusher is fed properly, wear will be uniform, resulting in longer hammer and disc life.  We can advise you on ways to feed your crusher properly so that parts wear and maintenance down time are kept to a minimum.

Also take measurements of bearing temperatures. A hot-running bearing will go out of tolerance and eventually fail; this is most often caused either by deterioration of the grease or by using too much grease. Check your operation manual, or give us a call for advice.

Ring hammermill/granulator examples

Cutaway illustration of the Pennsylvania® Granulator, a model that enjoys widespread use in the power generation industry. Over half of the coal used in power plants in the U.S. is crushed using Pennsylvania equipment. With the growth of coal for power generation in China and elsewhere, this model has enjoyed a strong surge of popularity around the globe.

The Pennsylvania Granulator, Model TKK. This is one of the larger versions of this model, showing the rear quadrant opened for inspection or servicing.

We’ll help you keep ‘em crushing

For more information, go online to www.penncrusher.com. You can learn more about our services, parts and remanufacturing. For general questions, please comment here on this blog, and I’ll respond here. If you would like Pennsylvania Crusher to review your crusher maintenance procedures, or if you encounter service issues, please call me at 610-544-7200, or send your E-mail request to fschaffer@penncrusher.com.

Fred Schaffer
Service Advisor
Pennsylvania Crusher

If anyone needed substantiation of the benefits of being a member of a special interest group such as the Australian Institute of Packaging [AIP] it became clear in early November when members of AIP were privy to a site visit to Visy- Recycling Glass at Laverton in Victoria.

Visy Recycling Glass in Laverton played host to a number of members from the Australian Institute of Packaging (AIP) on two separate occasions during November

AIP members gained an insight into the current state of play with regards to glass packaging recycling in Australia and were given the privilege of being able to see the automated glass sorting facility in action.

The state of the art facility is the only one of its kind within Australia and allows mixed and broken glass to be sorted into different colours, whilst removing high levels of contamination during the process.

Broken glass is sourced from kerbside collections and arrives from Municipal Recycling Facilities [MRF] all over the country. It arrives in various states of cleanliness from very clean to almost unrecognisable and in many instances loads of glass can be highly contaminated.

Contamination, the group was advised, comes in the form of Pyrex baking dishes, ceramic cups and plates and of course the usual nappies and plastics with the latter being removed at the very start of the process by manual labour.

The removal of ceramics is an area of focus for the plant because if a piece of ceramic gets between the shear blades during the glass bottle production process it can result in broken shear blades. Pyrex is also an issue because the melt point is different to normal glass and as a result can create weaknesses in the glass during carbonated beverage filling of the bottle.

The automated glass facility is totally computerised with each step of the process accessible and adjustable through a computer monitored system.

Optical Sorting

Using a process similar to a digital camera, the automated glass facility identifies and separates the different types or colours of glass by taking individual snapshots of each piece of glass at high speed. The light then identifies and processes the colour whilst air jets shoot the glass off into individual colour streams.

The cameras used in the automated optical sort have the ability to sort up to a million individual pieces of glass per minute and can detect up to 16 million different colours in total.

The facility was upgraded in 2005 and has driven glass recycling rates from 65,000 tonne to up to 120,000 tonne per annum or just under a 50% improvement in recovery rates since its completion.

In an attempt to recover as much as they can of the glass that enters the plant, the final act of recovery involves ‘aging’ glass that is rejected because it may have pieces of the paper label stuck to it. This can render it unreadable by the plants optical sort equipment, however material is stockpiled and then resorted through the plant to ensure that every possible piece of glass is recycled.

Every piece of glass that can be recovered and sent on for reuse in bottle manufacture is a win for the environment. Each 1,000 kg of glass used saves 1,100 kilograms of raw material being used.

Not only does the use of recycled glass reduce the energy needed to make new glass but it extends the life of raw material deposits and the costs associated with mining, processing and transporting over distances.

The generation of glass that is simply too small in size to recover is an inevitable part of the recycling process and this material can be used in road base and also for drainage base under roads because of the stability of the material, Visy Recycling Glass continues to work hard on sourcing new markets for this material.

Benchmarking on a global scale we still have room for improvement. Each year one of Visy Recycling Glass’ customers manufactures more than a million tonnes of glass, but only about one third of the glass in the waste stream is recycled.

High Recovery Rates

In Switzerland where recycling world's best practice exists 91% of manufactured glass is recovered for recycling. Albeit a small country like Switzerland does not suffer the Australian tyranny of distance to get waste to recycling facilities there is certainly room for a quantum leap in the volume of glass recycled.

A number of the visitors adjourned to a local watering hole to continue networking and must have reflected on a Visy statement that "a million people can drink out of the same bottle" as glass can be recycled forever.

Whether or not folks were drinking from a glass or stubby made of recycled glass is simply not answerable as there is no discernable difference between virgin material glass and that made from recycle.

The Australian Institute of Packaging can be accessed via the recyclable web site www.aipack.com.au whilst Visy-Glass Recycling can be accessed through the company's main site www.visy.com.au

by Michael B Halley
michael.halley@elmtree.net.au 
Austrlian Institute of Packaging (FAIP)
Reviewed by Meredith Banks
Visy Recycling - Corporate & Environmental Affairs