Probably the most frequently asked question from new waterjet owners, or those considering a purchase is, “What do I do with the used abrasive/garnet?” Considering that some machine set-ups can go through as much as 2 lbs/min of abrasive (the standard OMAX direct drive pump uses only 0.75 lbs/min) this can be a major consideration in terms of the use of this technology.
Most people first want to know is it hazardous? The short answer is no. Garnet comes from the ground and is a naturally occurring substance which is not hazardous and is considered standard solid waste. Of course if the materials that the waterjet has been cutting are hazardous, such as lead, they will end up mixed in with the spent abrasive and will need to be handled appropriately.
Generally the next question people have is how to get it out of the waterjet tank. There are a few different options here. Of course the lowest cost option is to jump in with a shovel and dig it out but this can be a back breaking job especially with a large table. The second option is to hire a septic company to come in and suck it out. The advantage to this is that it takes care of the removal from your facility in addition to getting it out of the tank. The downside to this option though is the cost. Often this can become extremely expensive and can be required every couple of months depending on the usage of the machine. The final, and most popular, option is a garnet removal system. These are often sold by the waterjet OEM and are easiest to install at the initial set-up of the waterjet. OMAX offers a variable speed garnet removal system that alternates between sucking spent abrasive and then purging the lines to keep drops of cut material from covering the nozzles. Many third party suppliers also sell add-on garnet removal options, some of which work extremely well.
Now that the abrasive is out of the tank the final question is what to do with it. Here again there are a few options. Some waterjet owners have found their own uses for it such as filling holes in the parking lot or selling it to companies that make pavers. The more common solution is to put it in the dumpster for removal by the trash company. The key to this is to let it sit outside for a while first to drain off all the water and reduce the weight of it before putting it in the dumpster. A final option that has become increasingly more popular recently is reselling it to garnet suppliers for them to recycle it and reuse it. GMA has been steadily increasing the geographic areas that they will come to for used abrasive pick-up and would be a good place to start if you’re looking for this service.
Abrasive is the single largest cost of owning and operating a waterjet and having a plan for disposal is a key piece of managing that cost.