Basalt crushing technique 1

I crushed basalt gravel for the first time today. While I was able to easily crush the basalt, I consider this first attempt to be a failure as I wasn’t able to achieve the results I wanted.

Canvas wrapped/4-pound hammer/concrete block

Goal

• To make enough basalt particles of the correct sizes to start running the SPORE Pressure Experiment 1.
  • 2000 microns (#10 sieve)
  • 63 microns (#230 sieve)

Equipment

• 0.5″-1″ basalt gravel
• A large chunk of abandoned concrete (used as an “anvil”)
• 4-pound engineering hammer
• 8 oz canvas tarp
• Geology screen sieve set
• Personal protective equipment (PPE)
  • Gloves
  • Impact resistant goggles
  • Dust mask (not needed)
  • Ear plugs (not needed)

Technique

1. I placed the tarp on the concrete block.
2. I wrapped a handful of basalt gravel in the tarp (I tried 1, 2, and 3 layers of tarp).
3. I proceed to beat on the gravel with the hammer. Usually with a single hand grip but sometime with a two-handed grip. I used what I consider medium force.
4. After about 20 swings I recovered the crushed basalt with a piece of stiff paperboard and transferred the sample to the sieve stack.
5. After shaking the sieve stack I moved a fresh piece of tarp onto the concrete block and placed the larger pieces back onto the tarp.
6. I transferred the contents from the #10 and #230 sieves into plastic baggies.
7. Repeat step 2.

 

Observations

• Breaking small basalt gravel (0.5″ to 1″ pieces) doesn’t require a lot of effort. I was easily able to do it with a 4-pound hammer without breaking a sweat while kneeling.
• I didn’t notice any large pieces of flying rock fragments even without the canvas covering the gravel. I also wasn’t hitting the gravel excessively hard.
• The canvas began to tear after the first impact. Almost every impact caused the canvas to tear more.
• I noticed canvas fiber fragments in the #10 sieve sample. This contamination is unacceptable. I discarded the sample. There were no canvas fiber fragments in the #230 sieve sample.
• Recovering the basalt dust from the tarp was a little more difficult than I anticipated.
• The 4-pound engineering hammer and geology screen sieve set worked great.

Conclusions

• Ditch the canvas. It started to come apart immediately and it contaminated the sample. Plus, it was difficult to retrieve the fine powder from the fabric.
• Ditch the concrete block. There are several reasons for this. One, it was impossible to recover any basalt that got loose onto the block because of almost certain contamination. Two, repeated blows to the block were causing it to disintegrate. Three, it’s located outside in a public place where people walk their dogs. The threat of a police encounter or stepping in dog poop kind of diminished my scientific excitement.
• I need to get a fine brush to help recover the fine powder. The paperboard scoop worked OK but I need something to get it onto the scoop.
• I need something hard and mobile to act as my new “anvil” if I’m going to continue to crush basalt by hand. My first thought is a cast iron skillet with a large block of wood under it. Flying debris is a concern. I guess I won’t know until I do it.
• The hammer worked great. I don’t see a need for a sledgehammer at this time.
• I could also go the mechanized route. A quick Internet search came up with a 6 lb ball mill with stainless steel balls for $160. Not exactly cheap but it may be worth it if it saves me a lot of time and produces the sizes I need. I can also try to build something but that may not be worth it at this stage. I’ll definitely need to eventually work on Lunar-built basalt crushing machines but that’s not what I’m focusing on now.

 

Photos

Sorry the photos are a bit small. Next time I won’t resize them so small.