Most of the crumb rubber produced in the US today comes from what is called the “ambient grinding process”. This process starts by taking whole tires down to 2” chips and then preferably on down to even ¾” minus size so you can then remove up to 85% of the steel to help from damaging the fine grinding equipment. Then the crumb rubber product is produced by using a crackermill mill or granulator or a powderizer. Running the rubber through these different machines allows you to achieve the size material needed to meet your particular customer’s needs.
In many cases you will actually use several of these machines in conjunction with each other to achieve the result or product that you need. This just means that the rubber is run through different pieces of equipment that essentially grind the material down into finer pieces by using friction which of course develops a substantial amount of heat during this process. Also to get smaller mesh size materials many times the rubber is further processed in what are called micro-mills. These mills are typically used in conjunction with water to create a slurry and this slurry material is then run through rotating abrasive disc to achieve the smaller size mesh particles. This is also considered an ambient grinding process.
The other method which is not nearly as popular because of the high cost of buying liquid nitrogen is the “cryogenic method”. With this type of processing you still need to get the whole tire processed down to at least two inches and preferably even smaller if feasible. Then you run this material into a freeze tunnel and add liquid nitrogen to the process and this allows the rubber to freeze and become brittle. Then this frozen material is fed into a hammermill with a small screen and the frozen rubber is shattered and made into many small pieces. The down side of this whole type of producing crumb rubber is not only the high cost for purchasing the liquid nitrogen but also the binding characteristics of this type of crumb rubber is completely different than crumb rubber that has been produced ambiently. Many manufacturers who use crumb rubber in their products have tended to stay away from this type of crumb rubber because they don’t want to have to do a lot of experimenting with their production process.
There are many different brands of equipment out in the industry today that are used in the production of crumb rubber. And of course some are better than others and a good rule of thumb when buying this type of equipment is to remember the old saying “you get what you pay for”. Much of what we presently see coming out of China works when you first purchase it but soon wears out and certainly doesn’t stand the test of time like many of the machines manufactured here in the United States. So please be aware of this and not let the initial price always be the determining factor when purchasing this type of processing equipment.
We also caution you to research your markets up-front and have a market already in place that will purchase your product once you’ve made this substantial investment to get into the crumb rubber production business. This is a very specialized industry and requires much more attention then just making TDF or rubber mulch. We welcome any questions that you might have about getting into this industry and hopefully will have the answers you need or will know someone in the industry that we can contact that will be able to get and answers for you. Unlimited Resources Corporation has sold and installed a number of crumb rubber systems and we can engineer a solution for your needs.