A few comments:

 The minerals in questions are alkaline. However, a mineral salt in aqueous solution may make the solution acidic. It depends. Sodium bicarbonate in water = alkaline solution.

Salt=Base+Acid

From http://jn.nutrition.org/cgi/reprint/121/11_Suppl/S89.pdf

for example,

7.52% glutamic acid - HC1 produced a diet pH of 3.65

and 2.20% ammonium chloride produced a diet pH

of 5.38, but consumption of each diet produced the

same urine pH (5.90). Therefore, when evaluating diets

for urine acidifying potential, diet pH is irrelevant.

These studies http://www.medscape.com/viewarticle/412220 and http://www.lpasteur.cl/PDF%20Referencias/Referencia%203.pdf indicate that Calcium Citrate is more bio-available than Calcium Carbonate.

 This study http://jcem.endojournals.org/cgi/content/abstract/65/4/801 (Enhanced Calcium Bioavailability from a Solubilized Form of Calcium Citrate) indicates that a mixture of Calcium Hydroxyde ans Citric Acid is more bioavailable than Tricalcium Dicitrate (common Calcium Citrate).

 This study http://jpet.aspetjournals.org/content/313/3/1217.full about Calcium formate:

“The high solubility and calcium content of calcium formate suggests that it might be an efficient source of calcium for dietary supplementation (DeLuca, 2003)”

...

“that calcium formate gave substantially and significantly greater increases in serum calcium concentration, greater ΔAUC for serum calcium increment, and greater decreases in iPTH than equimolar amounts of calcium from supplements based on calcium carbonate or calcium citrate, suggests that calcium formate may have considerable promise for use as a new dietary calcium supplement.”

...

“The present study has shown for the first time that calcium formate was clearly superior to both calcium carbonate and calcium citrate in its ability to deliver calcium to the bloodstream and to depress serum iPTH after oral administration. The high oral bioavailability of calcium formate, combined with its low molecular weight, high percentage of calcium content, and high aqueous solubility at neutral pH, suggest that its potential for use as a dietary calcium supplement merits further investigation.”

 Both Calcium Citrate and Calcium Formate are weak acids. Also both citric acid and formic acid can be used to make buffer solution. Maybe it is a desirable property.

 By the way, each time I measured the pH of the ML drink it was acidic, not alkaline. So, the ML drink to be alkalizing (or rather acid reducing) does not have to be alkaline.

 WIEL

P.S. A good article about Calcium Citrate http://www.advancedhealthplan.com/Calcium_Citrate.html .