The following items are common to wood and yard waste recycling operations.   Depending on what type of material you plan to process and what finished product you decide to make, you will only need a few of these machines to get started.  We have grouped the equipment into material 

 handling equipment, size reduction equipment, screening equipment, and composting equipment.

MATERIAL HANDLING

Rubber Tired Loader:

This is the most common type loader found at recycling facilities. It is used for loading raw materials into the equipment and moving finished products around the site. It should be able to dump materials over 10’ high and ideally should be able to load finished products into 13’6” high trailers. Smaller loaders will require that you build a ramp next to your equipment. If you process pallets or crating materials there will be a lot of nails around the site so tires will have to be foam filled.

Track Type Loader:

This machine is used like a rubber-tired loader plus it can be used for crushing raw material before the shredding or grinding process. By pre-breaking the raw materials with a track machine the shredder or grinder will produce a much higher volume of finished products. Small machines will require that you build a ramp next to your equipment. The disadvantage of this machine when compared to a rubber tired loader is that it cannot move as quickly over longer distances, cannot operate on paved surfaces and there are more wear parts.

Optional Bucket for Rubber Tired or Track Type Loader:

Either of the above described loaders can utilize a special light materials bucket commonly referred to as a high-lift or roll-out bucket.  Basically the bucket is designed so that it will lift and dump 3-4 feet higher than a standard bucket; this allows you to use a medium size loader to load semi-trailers from flat ground without building a permanent ramp.  This bucket is mentioned because in conjunction with the Rubber Tired or Track Loader it is one of the most cost efficient tools you can own in a wood recycling facility.  If you are interested in buying an Earthsaver high-lift bucket, please give us a call.

Track Mounted Excavator with Grapple:

This machine consists of an operator’s cab and a long boom (usually 25’) with a grapple on the end, mounted on top of a rotating platform and Caterpillar style tracks. It can be used to crush raw material, pile raw material, sort raw material, and feed raw material to the grinding equipment. It is mobile so can also be used for many other support activities such as shearing stumps and logs using an optional shear attachment. It is not practical for handling final products that are normally small in size.

Knuckleboom Loader with Grapple:

This machine consists of an operator’s cab and a long boom (usually 25’) with a grapple on the end and mounted on top of a rotating platform. It is usually installed on a hammermill grinder or a shredder and is used for self-loading raw materials into the equipment.  A benefit of knuckleboom loaders is that they can be used to sort through mixed materials and remove large items you don’t want to process, such as large stumps or tires prior to putting them in the machine. Don’t plan on using a knuckleboom to sort out small items; the operator is usually looking through a dusty window and visibility is not that good. Anytime a knuckleboom is used the operator station should be mounted high enough so that the operator can see into the infeed hopper of the shredder or grinder. This allows the operator to see and remove undesirable items, or shut down the machine, before they have a chance to damage the grinding mechanism. Also, it is helpful if the operator station rotates with the boom so that the operator is always facing the work area; this will reduce operator fatigue and improve safety.

Knuckleboom loaders are rated by the length of the boom, the lift capacity at 8’ or 10’, and at full extension.

SIZE REDUCTION

Stump Shear:

Use to reduce the size of large logs and stumps to a size more easily handled by a hammermill grinder, normally under 18” diameter, and to loosen any dirt or rock attached to stumps. It is normally mounted on a track type backhoe in place of the bucket, and can handle dirt without excessive wear.

Slow Speed Shredder:

Use for reducing the size of large diameter wood and stumps to a size more easily handled by a secondary grinder, and to loosen any dirt or rock attached to stumps. Although the name shredder is used to describe all slow turning machines that are used to shred materials, they are not all alike. 

One type is designed with close tolerances and is used to shred finely sized materials, 1” and less, and therefore can’t handle dirt without excessive wear. Another type, designed to shear, tear and rip, is not intended to produce particles smaller than 3” to 4” in length and can therefore accept dirt and small rocks with little adverse effect. For wood and yard waste applications we only recommend using a machine design that produces large particles, ones that must be processed a second time through a hammermill grinder.

Hammermill Grinder:

Use for grinding all woody materials. Hammermill grinders normally include horizontal grinders and tub grinders. Do to the high rotation speed of the grinding mechanism they can be set up to produce a wide variety of finished size material and are commonly used to produce landscape mulch or boiler fuel products. They are not as tolerant of dirt and rock contamination as slow speed shredders and small amounts of non-woody materials substantially increase wear to the grinding mechanism. Due to the high production rates experienced with hammermill grinders some non-woody contamination and the extra repair expense it causes is often considered acceptable.

The two most popular styles of hammermill grinders are Tub Grinders and Horizontal Grinders, and they are quite different in design and operation: See Introduction to Grinders for a description of tub and horizontal grinders.

Tub Grinders

Tub Grinders have been used in green waste recycling operations since the early 1980’s and are a dependable means of processing a wide variety of materials and sizes. The infeed hopper is basically a large tub, normally 10’-14’ in diameter that is easily loaded from the top with a front-end loader or grapple, and doesn’t necessitate the machine operator arranging raw material in any particular fashion for proper feed or operation. The operator can basically fill the tub and then leave to do something else while the machine is grinding, it isn’t necessary for him to watch the machine all the time. Tub Type grinders can normally handle material in lengths up to 15 feet and 3 feet in diameter. A disadvantage to this style machine is that due to the large open top tub and exposed grinding mechanism materials can be ejected back out of the machine if the tub is not kept full of material. This is a safety hazard if the machine is not located in an area that can be kept clear. A distinct advantage of tub type machines is in the way material is fed to the grinding mechanism; it is gravity feed, as opposed to force feed, and often the machine can be shut down for removal of unwanted materials such as a steel bar or large rock prior to any damage occurring to the grinding mechanism. On most Tub Type machines the tub can be raised to the vertical position for hammermill maintenance and for emptying the tub of its contents if necessary.

Horizontal Grinders

Horizontal Grinders have become popular in the last few years as an option for operating in areas where it is not acceptable for material to be ejected out of the machine during normal operation; the grinding mechanism is not exposed in a way that will allow material to escape out of the machine. Another feature is that the feed mechanism is normally of force-feed design, resulting in a higher rate of production in certain materials when compared to other types of grinders. A disadvantage is the feed hopper itself; material needs to be arranged somewhat better, as compared to the tub grinder, in order for material to feed into the smaller opening leading to the grinding mechanism. Another disadvantage, resulting from the force-feed design, is that the operator has little opportunity to remove non-woody material such as a steel bar or large rock prior to it coming into contact with the grinding mechanism, resulting in higher wear and tear. 

SCREENING

Flat Shaker Screen (Vibratory):

Used in conjunction with a Stump Shear to remove dirt and rock before the chunks of wood are processed through a hammermill grinder. It is normally fed with a rubber-tired loader following the shearing operation. Also used occasionally for final sizing of shredded wood products.  Shaker screens are designed to work primarily with rock and dirt so are normally not suitable for shredded wood products.  There are a few exceptions to this but generally they are more prone to plugging (blinding) when loaded with shredded wood.

Flat shaker screens are typcially described by length and width of uppermost screen deck.

Disc Screen & Star Screens:

A Disc or Star Screen is comprised of a long box with screening discs (or stars) mounted on rolling shafts that are installed close together and across the box. Pre-chipped material is put in at one end of the box and exits at the other end with the small acceptable size material falling down between the rolling shafts onto a product removal conveyor. When used following a hammermill grinder this kind of screen should effectively remove 95% of all contaminants such as plastic, paper, ferrous metals and aluminum cans from the shredded wood product and produce a reasonably clean wood chip product that can vary in size from a fine sawdust up to a maximum of 3” long by 1/2” in width. For this type sizing screen to be effective on material contaminated with paper and plastic the hammermill grinder must use product sizing screens with holes no smaller than 3” in diameter, otherwise the particles of paper and plastic will be too small for the disc or star screen to separate them properly. Acceptable size wood chips should make up approximately 90% of the total flow and rejected wood chips approximately 10%. A Disc or Star screen is sized by the width and length of the screen box, plus the number of shafts within the box. 

Trommel Screen:

A Trommel Screen is a rolling drum screen where material is put in at one end of the drum and flows through to the other end of the drum; during this action the acceptable size material passes through the wire mesh on the rolling drum and is carried away by a conveyor; oversized material passes out the other end of the drum and is usually carried away by another conveyor. The most common use of a Trommel is screening finished compost or mulch materials into two or more sizes. Trommels are the most popular screen to use when processing shredded materials that are wet or sticky because the trommel is self-cleaning and does not plug (blind) like is possible with a flat screen, and is capable of screening material to smaller uniform sizes than either the Disc or Star screen.

A Trommel Screen is also effective at removing other contaminants such as paper and plastic when using screen cloth with holes smaller than 3/8”, but is ineffective removing paper and plastic if the screen holes are larger. There is a spearing action that takes place inside a trommel which will occasionally force plastic though the screen with the acceptable end product, so plan to keep all raw material free of contaminants if you are using a screen cloth with larger holes.

Trommel Screens need to be sized by the square footage of usable screen cloth installed on the drum. The length and diameter of a drum is not always the correct indicator of production capability. 

COMPOSTING

Windrow Turners:

A windrow turner is used to aerate windrows of shredded and compostable materials. It works like an above ground roto-tiller to mix air and water into the windrow. Windrow turning is required in order to maintain microbial action within the windrow and to cause decomposition of the shredded material. There are a number of windrow tuners available which work with varying degrees of efficiency. The largest machines are self-contained, have their own power supply and are operated from an operators cab on the machine. Less expensive machines are pulled by a farm style tractor and powered by an engine mounted on the turner or by the tractors PTO. The appropriate size for a compost turner will be dictated by the size of your operation; the size of your property, how tall you want to make your piles and how much material you will have at any one time. The compost turner’s efficiency will dictate how often you must aerate the windrows and how many times you must turn them before composting is completed. Some machines turn an entire windrow in one pass while others turn one-half of the windrow per pass.

Compost turners are identified by the size of the windrow they’ll turn, the length of the rotating drum in the middle of the machine and how many cubic yards per hour they turn. 

Water Application System:

Compost needs a lot of water and a water application system will be necessary. Common systems may include one of the following: a water tank pulled by the turner; a water truck to spray or dump water on the windrow prior to turning the windrow; long hoses that run more or less continuously on the windrows; and more elaborate systems including permanent but mobile overhead watering.