| abstract |
Adducts of clay, especially of the smectite variety, most especially bentonite, are prepared with an effective amount of at least one activated mixed metal oxide or oxy-hydroxide (AHMMO) formed by dehydrating hydrotalcite or a mixture comprising magnesium oxide and aluminum oxide, or a crystalline mixed metal hydroxide conforming substantially to the formula LimDdT(OH)¿(m+2d+3+n.a)(A?n)a.xH2O where m is zero to one, D is a divalent metal, d is from zero to 4, T is a trivalent metal, A represents at least one anion or negative-valence radical of valence n, where n is 1 or more, (m+2d+3+n.a) is equal to or greater than 3, (m+d) is greater than zero, and xH2O represents excess waters of hydration. These adducts are useful, e.g., in drilling muds and in viscosity modification of a wide variety of fluids. |