Blood Meal: Evaluating Combustible Dust Properties and Hazards

Today’s episode of the Dust Safety Science podcast addresses the question of whether blood meal is a combustible dust. It came in through the Dust Safety Help Desk and, although we won’t go over the details of the blood meal incident that inspired the question, we’ll answer the following questions:

What is blood meal?
How is blood meal created?
Is blood meal a combustible dust?

We’ll also provide some examples of hazards that could arise from the presence of blood meal, based on our own observations and those of others.

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What is Blood Meal?

Blood meal is a dry powder. It’s usually a by-product of slaughterhouses or other meat handling facilities. The blood involved in that process can be dried and turned into a powder meal that’s a high source of both nitrogen and protein. Blood meal is commonly used to feed livestock, such as cattle, in order to increase their protein intake, and is also a material created for soil, as blood meal fertilizer. Bone meal is a similar material.

How is Blood Meal Created?

There are actually several different types of meals: bone meal, fish meal, feather meal, meat meal, etc. Like blood meal, these byproducts can be ground up and used for things like fertilizer and feedstock.

Blood meal and bone meal can be produced in a dedicated facility that takes the byproducts from neighbouring businesses and does all of the drying, grinding, mixing, and storage. Other companies process blood meal as an add-on to their existing operation. A meat processing plant with a separate area for blood meal production is a common example.

Is Blood Meal a Combustible Dust?

The short answer is yes. When blood meal is made into a powder and dispersed in the air, it can form an explosive mixture, and blood meal will be flammable. To answer this question, we conducted some independent research. We also reached out to some testing laboratories to see if they had any data.

Dust Explosions in the Processing Industries by the late Dr. Rolf Eckhoff contains a large table in the appendices. It lists different materials and sample testing results, and one of the materials listed is blood flour, which is another name for blood meal. They have it listed as 85 bar metre per second for the specific particle size and moisture content they were testing, and over 9.5 five bar overpressure, confirming it as an explosive and combustible dust.

If you go to the Gestis-Dust-Ex Database and look for blood meal, there are multiple entries. In a couple of them, the KSTS are greater than 100 bar metre per second and MECs (minimum explosible concentrations) range in from 30 to 60 gram per meter cubed.

Similarly, Cargill’s Safety Data Sheet lists dehydrated bovine blood as an OSHA-defined combustible dust hazard, and notes appropriate hazards such as ‘avoid generating dust’ and ‘combustible dust clouds may be created where operations produce fine material or dust.’

We reached out to a couple of combustible dust testing labs, which confirmed that they have tested blood meal and obtained results that confirm blood meal combustibility. When these findings are taken in conjunction with reputable publications and databases, we can confidently state that blood meal is indeed a combustible dust.

Combustible Dust Incidents Involving Blood Meal

One blood meal dust explosion took place at a beef packaging plant in Dodge City, Kansas, in 2019. The company had a separate area or separate building where they processed the blood meal afterwards and it ignited, injuring two workers. This incident highlighted the importance of isolating blood meal powder-processing operations at meat packing plants to reduce damage and decrease the chance of knock-on effects.

Another incident, which occurred in Norway in 1975, was covered in Episode #69 of the podcast. The facility produced fish meal and had a hammer mill system, with silos underneath the hammer mills. Dust built up on the inner walls of these silos, and when a screw or screws in the screw conveyor broke off, the tramp metal made its way into the hammer mill. When a worker opened the chute and went into the silos, an explosion resulted due to the dust build-up.

There are a couple of things that can be learned from this blood meal incident. Number one is that if you’re storing the blood meal material, you need to be cautious about blood meal dust accumulation. The second is the need to watch for fugitive blood meal materials in the hammer mill and manage them carefully when they do occur.

A paper called ‘Fire & Explosion Hazards of Meat & Bone Meal: Storage, Transport & Processing’ by Stephen J. Manchester from the Fire and Risks Sciences Division of the BRE Ltd. Group has a lot of interesting information about transportation and storage on blood meal. For example:

If you’re storing blood meal for a long time, you need to be really careful to avoid smouldering. Smouldering can be an ignition source for a combustible dust explosion as well.
You want to make sure that the blood meal material is not burning before loading or unloading it. This has happened a lot of times with wood pellets, charcoal briquettes, and other products prone to burning. If you create a cloud during the loading and unloading phase, you actually cause an blood meal dust explosion.
Layers of blood meal dust on hot surfaces and lack of an effective housekeeping program can lead to fuel being present when and if you have an incident involving combustible dust.

Blood Meal vs. Bone Meal as Combustible Dust

Blood meal and bone meal (a product composed of animal bones collected from slaughterhouses that are steamed and ground up) sound a lot alike, and they do have some similarities. Blood meal and bone meal both come from animals; bone meal is made from ground-up animal bones, and both are used as an organic, slow-release fertilizer; and both are sold in a form that looks powdery, named blood meal fertilizer. Both bone meal and blood meal as combustible dust form, require special handling and storage, and disbursement onto garden soil.

Blood Meal Dust Hazards and Gardening

When considering organic fertilizers, blood meal stands out for its ability to provide organic nitrogen in a concentrated form. However, gardeners should be aware of the potential hazard of combustible dust. Blood meal, in its unsifted powder ground form, can become an inert powder that poses a risk of explosion if not handled correctly.

Using blood meal as part of your soil amendments can be particularly effective for flowering plants and those that require high nitrogen levels. However, it’s important to balance blood meal with other organic fertilizers like feather meal, alfalfa meal, bone meal, and fish fertilizers to avoid nutrient imbalances.

When using blood meal and bone meal, remember that it’s an environmentally friendly fertilizer that can deter pests and support plant growth. However, always handle blood meal carefully to prevent the risks associated with combustible dust. Proper application and safety measures ensure that this powerful organic fertilizer contributes positively to your organic gardening efforts without compromising safety.

Conclusion

Blood meal, derived directly from dried animal blood from meat packing plants and poultry processing plants, is a popular organic fertilizer known for being high in nitrogen. This organic source of essential nutrients promotes vigorous plant growth, making it a favorite among organic gardeners. Adding blood meal to your garden soil can significantly enhance soil health. Always handle Blood Meal carefully to prevent the risks associated with combustible dust.

If you have questions about the contents of this blood meal combustible dust information or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.