The Tub Grinder at Work
There is a lot of activity going on in my compost yard - one of the most important areas on my farm.
During the year, my outdoor grounds crew amasses quite a large pile of organic debris - bark, stumps, logs, and brush. All of it is collected in one area and then either repurposed as milled lumber or left to decay and made into garden dressings, such as mulch and compost. To help with the decomposition process, I like to enlist the help of a tub grinder every couple of years. This large piece of machinery grinds the material into much finer, usable wood chips. Dan Repola, of Material Processors, located in Warwick, New York, has managed our projects several times. Once all the wood has gone through the tub grinder, Dan passes it through again to make it even finer and then mixes it with aged horse manure and chicken droppings to create nutrient-rich "black gold."
Enjoy these photos of this very interesting process.
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- For years, I’ve used a team from Material Processors – a 30-year old company that focuses on recycling green waste, and clearing and preparing land spaces for development.
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- These machines are extremely large and heavy, so Dan delivers the excavator and tub grinder to the farm the day before to set it up and prepare it for work. Tub grinders are named for the distinctive in-feed hopper – the large round tub, normally 10 to 14-feet in diameter and roughly six-feet deep.
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- Here is the excavator, which will pick up the material using the large “jaws grab” bucket attachment and drop it into the tub grinder.
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- The tub grinder is moved into position in front of the large wood pile. Dan then checks all the controls and makes sure everything is in good working order.
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- Here is a look inside the round tub. Dan makes sure it is empty and all the screens are in place before starting the project.
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- A continuous discharge conveyor carries the material away from the machine and piles it up in a mound.
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- Here’s Dan at the controls of the excavator early the next day. Dan has been doing this for many years and works very quickly and efficiently.
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- Dan begins operating the excavator and grabbing large amounts of logs and brush.
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- It is then transferred into the revolving tub of the grinder. There is a lot of dust and occasional debris flying around – it is very important to stay several feet away whenever visiting a tub grinder at work. Dan says he prefers to work on rainy days, which helps to cut down on all the dust.
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- Dan moves one load after another. It is always sad to see the trees go, but most of the big logs are from broken, old or fallen trees, and I am glad they can be repurposed into usable rich materials for the gardens.
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- As the tub spins, friction actually causes some of the wood to smoke. Everyone wears masks and appropriate eye gear for protection near the machinery.
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- Here is Dan carrying more debris with the “jaws grab” or grab bucket attachment.
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- The excavator works with a hydraulic system allowing Dan to raise and lower the long boom and bucket. Because the chassis is built on top of the undercarriage, it is also able to rotate 360-degrees.
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- Once Dan has the bucket over the grinder, he opens the “jaws grab” and releases the debris into the hammermill at the bottom of the tub. As the tub revolves, the hammermill shatters the wood into smaller fragments.
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- And then after everything runs through the grinder, the result is good, usable wood chips and mulch.
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- My property director, Fred, flew the drone to get a couple more shots from above – here is a better look. The grinding process is actually quite mesmerizing to watch. It is also extremely loud – the tub grinder can be heard all the way on the other side of the farm.
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- Here, the grinder is filled with more debris, but it quickly disappears into the grinder. Any boulders are moved to the side in another pile.
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- Soon, the wood fragments from this load will travel on the long conveyor belt, adding to the large mound next to the machine.
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- Dan continues the process for several hours, but he will be at the farm for two to three days to complete all the work. You can see how finely the wood is ground up.
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- Dan runs it through a second time to make it even finer and then mixes it with our compost.
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- He also screens the older piles of decaying matter, turning it all into the dark and rich compost I like to call “black gold.”
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- I just love that all of my garden beds are top-dressed and enriched with gorgeous compost made right here on the farm. Thank you, Dan, and Material Processors. This is great.
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