Miller Magazine Issue: 125 May 2020

53 COVER STORY MILLER / MAY 2020 mental consideration globally? Whatever the pressures, whatever the solutions, one thing is certain: Grains will continue to be center stage in world efforts to feed a grow- ing population. With safe storage, proper grain handling, we can escape the confines of the nation in the Byzantine proverb. It is important for the individuals responsible for growing, buying, storage, handling and processing grain to know the handling systems. Storage facilities, handling systems, and atmospheric conditions can significantly affect the quality and value of the grain. Grain grading systems reflect dam- age to grain that occurs during storage and handling. Un- suitable mechanical equipment can cause changes in qual- ity such as increase in kernel breakage and amount of fine dust in the grain. The penetrating and residual musty odor coming from mold growth is a concern in grain grading; ac- cordingly, such grain is designated as smutty. Heat damage results from conditions developed during storage. According to the U.S. grading system, more than 0.2% heat-damaged kernels degrades grain to No. 3 grade. Such physical, chemical, and biological changes in grain quality can be avoided if conditions during storage and handling are properly controlled. INTRODUCTION The infrastructure associated with grain storage is a ma- jor component of the grain management system. A grain storage and handling facility includes grain receival, grain movement, grain cleaning, reclaim, cleaning and storage operations. This is a major investment and the whole sys- tem must be carefully planned. Facilities for the storage and handling of grains (and processed grains) should be com- patible for whole grains, ground grains or processed grains. Design Objectives Grain storage and handling facilities should be designed, constructed and maintained to ensure that • Process flow and layout of the distribution system is suit- able for the types and characteristics of the materials to be handled and the operational requirements of the facility. • Quality of the grain handled is not compromised by con- tamination by insects or rodents. • Personnel, equipment and overall facility safety issues are implemented. Mandatory Requirements Compliance with • AS1657 -1992 Fixed platforms, walkways, stairways and ladders – Design, construction and installation for access, stairs, landings etc. on grain storage and handling equip- ment. • AS2865-2009 Confined Spaces for confined spaces entry requirements. Facility Layout The type of construction and the amount of available land may determine the physical layout of the facility. The relative location of the areas designated for grain receival, feed preparation, loading and feeding out will affect the operational efficiency and costs of running the facility. Design considerations for each storage and handling facility should include • Storage capacity • Handling rates • Capital cost • Short-term (e.g. pad/bunker) versus long-term (e.g. silos) infrastructure • Allowable level of grain degradation • Protection of grain from spoiling, insects, pests and vermin • Maintenance requirements • Process flow/layout requirements • Automation • Lot identity conservancy • Built in flexibility • Expected life of the system • Safety (e.g. dust explosions). Grain Characteristics Grains can be divided into three groups: cereals (maize, wheat, barley, sorghum, rice); pulses (lupins, beans, peas); and oilseeds (soybeans, sunflower, linseed, canola). Different grains and grain types have a range of char- acteristics that can affect the type of distribution system selected and the components required in the distribution system. These characteristics include moisture content, res- piration of the grains, angle of repose of the grains, abra- sion of the grains against contact surfaces and ease of flow of the grains. A brief description of moisture content and angle of repose follows. Moisture Content Moisture content in grain is defined as the amount of wa- ter that is absorbed into the grain kernel as a percentage of the total weight of the grain kernel. The moisture content of a grain is typically provided on a ‘wet basis’ (wb) and is calculated as Standard grain grades with moisture contents of 13–18% do not usually cause material flow problems. But high mois- ture content grain, when coupled with high foreign material contents and fines, can lead to material flow and handling problems. Moisture content of the grain can change with the environment in which it is stored and this should be monitored to help ensure the overall condition of the grain. Graphical representation below illustrates the potential issues with stored grain at a range of temperatures and moisture contents. As the temperature rises, the safe level of moisture in the grain must be reduced for good quality storage.