Bulk Material Handling

Understanding the Dynamics of Material Flow

The challenges of conveying and processing dry bulk material are often not readily apparent to processors when select bulk material equipment. The consideration of factors that is attributed to equipment size and selection focus on;

  • Bulk density
  • Minimum/maximum partial size
  • Particle properties
  • Environmental considerations – humidity, toxicity, ambient temperatures, shipping distance
  • Type of material – chemical, organic, inorganic, food-based, pharmaceutical or nutraceutical, or agricultural

These are just some of the foundational elements considered when equipment is selected for conveying, feeding, unloading, and filling. Challenges arise when these are the only elements considered when equipment is designed. Processors share in the frustration of dry material systems not meeting production capacity and struggle with material flow issues even though equipment is sized and rated for the specified elements listed above. You can read our Application Review: En-Masse Twin Chain Retrofit Gets a Brazilian Wood Products Manufacturer Running at Full Capacity as reference to this point

Unlike gaseous and liquid systems where in absence of pressure drops, the state of the product conveyed or transported does not fluctuate much. In bulk materials however, this is not always the case. Bulk density as an example is not a constant figure. The same material can have varying bulk densities in different stages of production causing flow rates to change creating the need for processing formulas to be adjusted. There have been numerous studies and articles written to try to explain this dynamic.

Influence of Feed Material on the Performance of New Plants

CDM understands the effects of bulk density changes on the efficiency of new equipment installations.

Studies also show that start-up systems for material solids typically only hit 40% of stated production rate in the first year.* This is a dramatic figure when considering the wide range of industries which process bulk solids. Food, nutraceutical, pharmaceutical, chemical, building materials, minerals processing, and others are challenged by the shear characteristics of the raw materials of the process.

To overcome these challenges, best practices suggests having material tests performed prior to equipment purchase and experience. Relying on an experienced vendor who has tested, and understands the dynamic nature of bulk materials to guide equipment layout and options to avoid pitfalls in expected output.

*source: Bell, 2005, Challenges in the Scale-up of Particulate Process – An Industrial Perspective, Powder Technology, 60-71

Material Density Guide

This guide lists common minerals, production by-products, ingredients and their corresponding bulk density. Note that the listed bulk density is nominal and should not be considered exact for your application. Material density can change when in storage, or in high moisture environments.

Material Bulk Density (lb/ft3)
Alumina 50-65
Aluminum (Hydrate) 18
Aluminum (Ore) 75-85
Aluminum (Oxide) 67-120
Apatite Phosphate 75-80
Ash Dry (Coal) 35-40
Ash Wet (Coal) 45-50
Barley 38
Bauxite 68
Bauxite (Mine Run) 80-90
Blast Furn (Dust) 85-105
Borax (Fine) 53
Buck Wheat 40-42
Cal Carbonate (Limestone) 56-69
Calcium (Nitrate) 75
Cal Oxide (Burnt Lime) 68-82
Carbon Black (Pellets) 12-44
Cement (Finished) 69-94
Cement (Raw Meal) 31-56
China Clay (Kaolin) 31-94
Clay (Calcined) 62-82
Clinker (2″ Minus-Dust) 75
Coal (Anthracite) 55-60
Coal (Brown Culm) 37-50
Coal (Bituminous) 45-50
Coal (Lignite) 40-45
Coal (Dust/Pulverized) 25-50
Coffee Beans (Green) 36-44
Coffee Beans (Roasted) 22
Coke Breeze 25-35
Coke Dry 23-35
Coke Calcined (Petroleum) 35-45
Compost 28-30
Copper Ore 120-150
Copper (Sulphates) 50-75
Copra (Whole/Broken) 28-31
Copra (Meal) 22
Corn 45
Cotton (Lint 12%) 16
Cotton (Lint 4%) 22
Cotton (Dehulled) 28
Electrostatic (Precip Dust) 6-82
Extractor (Cake & Meals) 19-31
Ferric Oxide (Iron Oxide) 50-69
Fly Ash (Flue Dust) 19-50
Foundry Sand (Flue Dust) 62-90
Grains (Whole) 45-50
Gypsum (Pulverized) 44-75
Hops (Spent Dry) 35
Iron Ore 62-106
Iron Ore (Ground) 135-150
Iron Pyrite (Residue) 75-87
Lime Hydrate 31-56; 135-150
Limestone (Crushed) 85-90
Litharge 75-94
Litharge (Lead Oxide) 200-250
Linseed (Flax) 37-45
Malt (Dry) 34-37
Magnesium (Chloride) 33
Magnesium (Oxide) 25-31
Millet 42-47
Nickel (Sulphates) 50-75
Nickel (Calcine) 75-82
Nickel (Pyrite) 144-206
Phosphate Rock 69-82
Phosphate Rock (Coarse) 62-106
Phosphate Rock (Fine) 62-106
Potassium (Chloride) 56-69
Potassium (Sulphate) 69-75
Pyrite Ash 75-87
Potash (Dry) 56-69
Potash (Muriated) 56-75
Quartz Sand (Silica Sand) 82-100
Rapeseed (Canola) 37
Safflower 37
Salt 44-100
Salt Cake 6-8
Saw Dust 6-12
Sinter Dust 75
Slag (Dry) 31-62
Slag (Wet) 62
Soda Ash (Dense) 56-62
Soda Ash (Light) 31-44
Sodium Sulphate) 69-106
Sorghum 42-47
Soya Beans (Not Cleaned) 45
Soya Beans (Cleaned) 45
Soya Beans (Hulled) 8
Soya Flakes 17
Soya Meal 28
Sugar Raw 50-56
Sulpher (Dry) 62-75
Sunflower (Seed Whole) 25
Sunflower (Seed Hulled) 17-28
Sunflower (Hulls) 6
Thomas Slag 82-112
Urea 37-47
Wheat 45-49
Woodchips (Sized) 13-25
Wood Pellets (1/4-3/8” x 2” Lg) 30-40
Wood Slivers (Sized) 3-10
Zinc (Calcined) 110-150
Zinc (Oxide) 10-35