Patent ID: 6887517

Claim:
A method of producing a surface-modified particle comprising: (a) reacting a particle having a particle size less than 5 mm and a surface shell comprising at least 5% aluminum oxyhydroxide, iron oxyhydroxide, scandium oxyhydroxide, a solid solution of aluminum oxyhydroxide and iron oxyhydroxide, clay or mixtures thereof with a first reactive compound having an anchoring group and a first reactive group which is a first member of a Michael-type donor- acceptor pair, whereby the anchoring group reacts with the particle, producing a first surface-modified particle; and (b) reacting said first surface-modified particle with a second reactive compound, said second reactive compound having a second reactive group which is a second member of the Michael-type donor-acceptor pair by a Michael-type addition, producing a second surface-modified particle.