Building a mill to make the products you need

By Fred Fairchild

This is the fourth in a series of articles on planning a new or expanding an existing facility. In the February 2018 issue of World Grain, we examined factors to be considered when deciding where to build a new feed mill. In the April 2018 issue, we discussed the mix and amounts of products needed to be produced by the facility. We determined initial and future production rates needed to make the amount of feed needed in each case. We also determined the final shipping form, bulk or bagged for the finished products.

In the May 2018 issue, we introduced two generic product formulas. The first is a generic Starter/Grower Broiler feed. The second is a generic 18% Swine Starter pelleted feed. Using these formulas, we picked out the location or systems where each ingredient was located to be added to the mix for a complete formula. Using the ingredients from these formulas, we calculated the amount and type of storage needed for each ingredient and where that was located.

In this article, we will determine the steps needed to produce the required products and develop a block flow of how the processes and steps are connected. The products made include mash feed, pelleted feed, textured feed, processed whole grains (rolled), premixes and bulk or bagged shipment. Using this information, the mill must be able to use grinding, flaking (for textured products), batching, mixing, pelleting, texturing and premixing systems.

Each of the steps in the process can be defined as a manufacturing step. Once all the required manufacturing steps are identified, we will draw a Block Flow Diagram showing how the steps are related.

Manufacturing steps

Receiving: Many different ingredients need to be received to make the required finished feed products. This would include grains, protein meals (soybean meal, etc.), wheat middlings, distiller’s grains, minerals and other large use ingredients that are received in large size shipments and stored in large bins. Liquids delivered in large quantities such as fat, molasses or others are delivered in truck or rail car lots. Large tanks with temperature control are needed for this storage. Most bulk ready-to-use ingredients are stored in overhead working bins above the batching system.

Smaller ingredients such as micro-ingredients and premixes are received in bagged form or totes. Even little-used liquids may be received in liquid totes. All of these ingredients require physical handling and are kept in storage in a warehouse setting before being used.

Raw Ingredient Pre-Processing: Whole grains and other ingredients such as alfalfa pellets are normally ground into small size particles before being sent to the overhead working bins above the batching system. If textured feeds are made, the whole grain is steam-treated before being rolled or flaked for the formulation. Any facility using an ingredient that needs to be processed before using must be equipped to do the necessary processing.

Batching: Once all ingredients for the formulation of the various products are in the proper form, they are placed in overhead working bins above the batching system. The amount of each ingredient for a given formula is metered into the scale hopper and weighed to get the proper amount of each ingredient for the formula. The micro-ingredients, except for items to be hand-added to a formula, are individually weighed up in a micro-system for delivery to the mixer. Once the dry ingredients are all weighed up in the main scale(s) and/or micro-scale system they are ready to be discharged into the mixer.

Mixing: The ingredients dropped from the main scales are mixed for a specified length of time, including the addition of the micro-system ingredients for the formula to get a uniform mix of the dry ingredients. This is called the “dry” mixing time. Once this time is reached, the liquids are added to the mixture and mixing continues as a “wet” mix time until the total mixing time needed for uniform blending of the ingredients is reached. This mixed formula is discharged from the mixer and may be sold in mash/meal form or further processed.

Pelleting: The mixed mash may be further processed to make pelleted products. The pelleting process incudes adding steam to a mash to raise its temperature and make it a wet mash that is forced through a series of holes in the surface of a die that forms the mash into pellets. The pellets may be used as a finished product or passed through rolls to crumble the pellets.

Textured System: Flaked or rolled grains are incorporated with other ingredients and liquids in a continuous mixing system.

It is a continuous mixing system in which all the ingredients are measured through individual feeders simultaneously into a constant running mixing screw.

Liquids, such as high percentages of molasses, also are metered into the mixing screw continuously and the mixed textured product is discharged into bulk trucks, totes or bags and not put into storage due to the high levels of liquids that would cause flow difficulties in getting the product out of a bin.

Bulk Loadout: The finished products are stored in bins or directly loaded into bulk trucks and trailers. The bins usually are of larger size to hold multiple loads of a given product. In some cases, a few smaller bins may be used that hold one to two loads of special products. There also may be bins assigned for holding medicated feeds.

Bagging: The product is manually or mechanically placed in bags and sealed. These can be small (50-pound bag) to a large tote (2,000 pounds). In addition to filling and sealing each bag, the bags are stacked on pallets to move them to warehouse storage.
 

Flow diagrams

Once all the steps are identified as needed for producing each product for the feed mill, a block flow diagram may be created. This diagram shows all the steps needed to make all the required feeds. No storage bins, working bins or warehouse are shown on a block flow diagram as its sole purpose is to show the needed manufacturing steps. As you look at the block flow diagram, it shows ingredients are received four ways — bulk grain, bulk ingredients, bagged ingredients or liquid — as indicated by the four steps shown at the top of the diagram.

Bulk grain may be used as whole grain going directly to the batching scale, flaking of grain for the textured grain system or sizing of grain before the batching system. Other bulk ingredients are received in bulk or bagged form ready to be used in the batching system, or sized (ground) before going to the batching system.

Ingredients weighed in the batching scale and micro-system are then discharged into the mixer. The liquids are added during the mixing cycle for most products and added in the texturized feed system. The mixed formula may be sold in mash (meal) form in bulk or bagged form.

The mash may be further processed into pellet form and delivered to the bulk or bagged loadout systems. Product from the textured feed system goes to either the bulk or bagged loadout.

Once all the steps needed to make the required feed products are determined, a block flow diagram for the facility should be prepared. Using the block flow diagram, an actual process flow diagram may be prepared for the facility in which all required steps are included as well as storage and working bins.

The process flow diagram is the most important document needed to design or expand a mill facility. It shows how all steps are tied together and the sequencing of the steps. The flow will influence the actual physical layout of the mill and mill sit.

In future articles, we will explore the individual processing steps and suggestions to be considered when designing the same.

Source: WORLD-GRAIN.COM