How to feed magnesium powder
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If magnesium powder, such as 200-mesh grade, is to be used in production, how can safety during feeding be ensured? Feeding materials into the reactor causes them to float around, and over time it’s difficult to prevent collisions that could generate sparks. It seems that magnesium can also react with nitrogen! It is said that many companies have been forced to switch to magnesium shavings and magnesium strips!
Can we use a dosing machine to add water to the powder first to form a suspension, and then add it?
Magnesium powder is generally used as a Grignard reagent; adding water definitely won’t work. I’m thinking of first moistening it with a solvent (so that no suspension is formed), and then adding water! If the amount is too large, it becomes difficult to handle (due to the solvent’s odor and the need for manual handling, etc.), and a large amount of solvent is required to rinse it away! What kind of device is the dosing machine you mentioned? !
This post was last edited by li*nji on 2015-12-9 at 14:52. A powder tank is used; either the weight of the powder causes it to flow downward or an anchor feeder is employed to feed the powder into the mixing tank containing solvent. After thorough mixing, the powder is added in fixed quantities using a positive displacement pump.
It’s better to just pour the magnesium powder directly into the reaction vessel – the concern is that during pouring, the magnesium powder might scatter and collide, generating sparks that could cause an explosion! What I have in mind is that when the amount is small, it can be manually scooped up and added to the organic solvent, before being poured into the reaction vessel!
Chemical operations should avoid any potential risks; if one proceeds with them despite knowing such risks exist, it’s playing with one’s life! ! !
So we need to find a way! Otherwise, how can one make progress!
First, the explosion limit should be considered: under your operating conditions, will the magnesium powder concentration exceed the explosion limit? If it does not reach the explosion limit, no explosion will occur even if sparks are generated. Personally, I think one approach is to create a suspension in a small, sealed container and then add it to the reactor, as small containers are easier to handle and make it simpler to ensure that the product does not reach its explosive limit; moreover, when the suspension is added to the reactor, there is less risk of powder floating around. Finally, the reaction vessel must be cleaned regularly to remove the powder that accumulates in the stirring dead zones.
After the reaction is carried out several times, the reactor is filled with organic solvent vapor, and it seems that magnesium powder can also react with nitrogen – so how can one determine the explosion limit? How are the workshops where magnesium powder is produced protected? !
Ask the supplier how the manufacturer loads magnesium powder into the barrels Guesswork: Use a solvent that does not explode upon mixing, pump it to circulate, and return it to a large container. A ejector (a Venturi ejector that creates negative pressure) is connected to the pump outlet pipe; the negative-pressure side of the ejector is connected to a container for measuring magnesium powder (or the feed hose can be directly inserted into the magnesium powder tank), and the feed rate is controlled via a discharge valve. Before each use, calculate the amount of solvent and the quantity of magnesium powder to be added. Start the circulation pump to dissolve the magnesium powder in a closed loop system, and then add it to the reaction vessel.
Magnesium powder is a silver-white, metallic-looking powder with the molecular formula Mg; it is a reactive metal that catches fire easily when exposed to moisture. It is irritating, causing irritation to the eyes, upper respiratory tract, and skin; inhalation can lead to coughing, chest pain, etc., and ingestion is harmful to the body. It produces a strong white light and releases a lot of heat when burning. It reacts violently with water or moisture, releasing hydrogen gas and generating a large amount of heat, which can cause combustion or explosion. It reacts violently with chlorine, bromine, iodine, sulfur, phosphorus, arsenic, and oxidizing agents, posing a risk of combustion and explosion. Powders and air can form an explosive mixture; when a certain concentration is reached, an explosion occurs upon contact with a spark. Ignition temperature: 550°C; lower explosion limit: 44–59 mg/m3; minimum ignition energy: 40 mJ.