Opaline Silica Thread

There were some valid questions in there before the handles broke off… aha! Found them!
@Curious_Roberto asked about dust and filtration. The particles are screened to be between 16 & 30 mesh. They also make them in 8/16 mesh, I believe, which are bigger. However, like any hard particles rubbing against one another they can undergo attrition by wear, forming dust. This becomes more pronounced after drying… just because dry dust floats around more than moist dust.

As I have written in the past, depth filtration is important to achieve stringent particle removal and reasonably fast flow. This can be achieved using a strong screen supporting the media’s weight above some cotton wadding, filling the space between the screen and another sheet of screen over the outlet hole… not packed too tight, but tightly fitting around the sides, where dust would like to channel. Technically, even depth filtration cartridges can be used. Probably the easiest way to utilize a single media like this is to fill up a polyester bag filter, maybe 10-25μm, make sure it has good bottom support and probably a stainless steel top opening ring, and the bag housing should empty from the bottom. This flows into a large pleated depth filtration cartridge that filters down to 1μm or less, in layered steps, such as 25-15-10-5-1-0.5μm or something similar.

@RockSteady asked if this should be milled and classified or used as is. The short answer is “Yes.” As you probably know, the narrower you can get your particle size distribution (PSD), the better your flow rate will be… differently sized particles will always pack tighter than evenly sized particles. However, attrition happens. Dust and smaller particles are an inevitability. You could pulverize this stuff, but beware the intensely dusty aftermath and likely slower flow rate! Even leaving the particles at 8/16 mesh (which I was using, NOT the smaller pictured 16/30), getting all the liquid butane out of it could take up to an hour while it was cold (around -50°C), and getting all of the butane out without actively warming the granule chamber (NO HEAT GUNNING, only warm water jacket!!!) was practically impossible.

I always dried the 8/16 granules in thick aluminum foil lasagna pans, as it was, in layers no more than 3" thick, under dry scroll vacuum, in a big dedicated vacuum oven, at about 300°F (the highest it would go without destroying the door seal… much). The dust eventually destroyed the pump, which is why I recommend covering the pans with 100% cotton pillowcases, like I always did with activated charcoal dust. I would allow it to dry at least 12 hours, keeping a pan under the pump exhaust for all the water flowing out of it. Then I would turn the temperature down to 100°F and allow it to cool to that temperature, still under active vacuum.

I prepared clean dry 5(.86)-gallon HDPE buckets with those air-tight screw-on Gamma Lids. I would vent the oven, leave the room (no need to dust up the clean oven room), and deftly pour the warm granules from the aluminum pans into the buckets to fill them within an inch of the Gamma Lid interior lower rim, make sure the gasket and sealing bevel was wiped clean and in place, then screw on the lid tightening with only 1 hand in the center… that way I could always open the lids using 2 hands.

I used it as granules, because it worked just fine, and powder would have caused more problems, as I mentioned above. I filled a 6" × 36" sock up to about 23", then loosely twist tied the top shut and loaded my 6" × 26" tube (24" + 2" screen plate segment), resting the sock on the 2" deep side of the reinforced 10μm screen plate segment mounted over an empty 6"-3" conical adapter, terminating in a 3" bowl with 2×0.5" compression adapters, which had a 50μm screen in the bottom, covered by 12 to 15 vertically oriented spiral cotton balls arranged to fit perfectly inside the bowl, which was topped with a 50μm screen buna-n gasket. These cotton balls were changed every 2 to 4 runs, when the granules were changed.

The top 6" tube was flange was cleaned of all dust and topped with a 6" 10μm screen buna-n gasket and a flat cap with 5 separate ball valves on 5 NPT ports, the central port having a stand pipe and T with a pressure gauge on top and a ball valve on the side of it. The 4 perimeter ports were for the 4 separate column lines from the heavily modified EX40 system. The T valve came from the outlet of a stainless/PTFE AODD pump that was fed by a T from the pour spout on the massive collection/evaporator tank on the system. This way, I could use the media first by flushing the cold butane extraction solution through it directly from the 4 columns, central valve closed, down through both outlet holes (for backup and extra flow) into the collection tank. Then, if the color wasn’t light enough with a single pass (like when it was on its 2nd or 3rd run), I could open the tank pour spout T to the pump, close the top 4 periphery valves on the CRC, open the T center valve to the pump outlet, and recirculate the warm (90°F) butane:resin solution through the CRC and back into the collection tank, watching the color lighten to the point desired through the collection sight glasses (while speeding up recovery tremendously with the spraying action from the liquid butane pump, btw).

The opaline silica load in this unit was 600 cubic inches of 8/16 mesh granules. With old dark resin trim, we could get about 20 kilos biomass worth of resin to a nice light gold. With amber gold resin biomass, the first 10 kilos worth would be water white transparent, and then straw to gold on the next 20 kilos. So the average usage was about 25 cubic inches dried opaline silica for every kilogram of biomass resin in n-butane.
There were about 5 loads in every 50lb (wet weight) sack, meaning each load cost about $2. At 4 runs per load, the media cost was about 50 cents. It can probably be regenerated by washing with acetone, but that process is too dangerous and messy to bother with for half a buck.

There are more efficient ways to run with this material. Namely, @cyclopath 's 2-cartridge switching system, to change media socks mid run, using 1 sock per run. Combining that switching unit with inexpensive inline depth filtration cartridges would be ideal.

32 Likes