# effect of solution contact angle with KCl and NaCl ore on dissolution rate

I am working on a potash solution mining project (NaCl solution injection) and it is said that in the mine cavern, the contact angle of the solution with cavern wall can have impact on the dissolution rates, i.e. on the bottom of the cavern, the dissolution rate is much lower than at the top of the cavern (due to a variety of factors), but we are just trying to capture it with a multiplier on the default rate (the kind of rate measured in lab on vertical surface).

Here is a very rough diagram showing inside the cavern, solutions are injected into it to dissolve ore on all faces. On all surfaces, solution and brine will enter and leave and there will be some flow along those angled faces, which will result in some differences in the dissolving rates.

I did a lot of search online and in various libraries, journal articles, lab reports, I am surprised that there is very scant information on this (i.e. contact face's orientation impact on dissolution rate). Any pointers would be greatly appreciated.

• Can you elaborate little more what you mean by the contact angle? Possibly with illustration? Does it mean the normal vector orientation of the contact surface solid-liquid? In such a case, density gradient would definitely affect disolution rate by supported or suppressed convection. Hard to quantify as diffussion coefficients dramatically change with salt concentrations and also there is diifficulty with defining properties of transient layers. Commented Mar 25, 2022 at 8:26
• @Poutnik I've updated the question with a cartoon drawing of the cavern. Again, I can find no definitive lab experiment or qualitative description of the differential dissolution rates based on the contact angle inside the cavern. Commented Mar 25, 2022 at 16:18
• Hard to quantify but qualitatively, is not it obvious? From upper surfaces, enriched dense solution flows down, replaced by fresh liquid. At bottoms surfaces, it tends to stay sitting down, slowing dissolution. Even with forced mixing, the effect partly remains. But I guess this you know and ask for something else. // Do you mean really potash (K2CO3) or rather potassium(K) in form of KCl? Commented Mar 25, 2022 at 16:50
• It is KCl solution mining. Yes, qualitatively it is clear that the rate would be faster at the top than at the bottom. I am looking for quantitative measure of the magnitude of such differences based on contact angle, most of the lab measurements I saw were done on vertical surface, I wish there are documents/labs done to quantify such effect, any pointers? Commented Mar 25, 2022 at 17:33