Method of decalcifying rare earth metals formed by the reduction-diffusion process

Claim 1

A method for preparing a mixture of a rare earth and an intermetallic compound comprising said rare earth and a ferromagnetic metal selected from the group consisting of iron and cobalt comprising the steps of: (a) reducing a compound of said rare earth with calcium in the presence of said metal at an elevated temperature; (b) heating the product of the reducing step for a time and at an elevated temperature sufficient to diffuse most of said rare earth into said metal and produce a cake of said mixture containing CaO and unreacted Ca; (c) hydrating said cake with water in a substantially CO 2 -free environment to alkalize said CaO and Ca into Ca(OH) 2 and crumble said cake into a mass of particles having a first fraction comprising principally Ca(OH) 2 having a portion of said mixture entrained therein and a second fraction comprising principally said mixture; (d) treating said first fraction with an aqueous alkaline solution containing a reagent capable of forming a calcium salt soluble in said solution; (e) maintaining said solution at a pH sufficiently greater than 9.0 during said treating step to substantially prevent dissolution of said rare earth while forming said; and (f) removing said solution from said mixture; whereby said Ca(OH) 2 is separated from said mass with substantially no loss of said rare earth therfrom.

Claim 2

A method for preparing a mixture of a rare earth and an intermetallic compound comprising said rare earth and a ferromagnetic metal selected from the group consisting of iron and cobalt comprising the steps of: (a) reducing a compound of said rare earth with calcium in the presence of said metal at an elevated temperature; (b) heating the product of the reducing step for a time and at an elevated temperature sufficient to diffuse most of said rare earth into said metal and produce a cake of said mixture containing CaO and unreacted Ca; (c) hydrating said cake with water in a substantially CO 2 -free environment to alkalize said CaO and Ca into Ca(OH) 2 and crumble said cake into a mass of particles having a first fraction comprising principally Ca(OH) 2 having a portion of said mixture entrained therein and a second fraction comprising principally said mixture; (d) treating said first fraction with an aqueous alkaline solution containing a reagent capable of forming a calcium salt soluble in said solution; (e) maintaining said solution at a pH sufficiently greater than 9.0 during said treating step to substantially prevent dissolution of said rare earth while forming said; and (f) removing said solution from said mixture; whereby said Ca(OH) 2 is separated from said mass with substantially no loss of said rare earth therfrom.