the presence of moisture however agglomeration by spray drying is in general preferred for its flexibility and economy of operation on a production scale the particular conditions under which the slurries are formed and spray dried are well known and are not a necessary part of this description a detailed description thereof may be found for example in u s pat no 3 617 358 issued nov 2 1971 depending upon the application envisioned the spray dried agglomerates may be classified usually by screening in order to obtain a desired particle size distribution for example within a range of about 60 micrometers and preferably 80 percent within a range of 30 micrometers for flame spraying applications while practice of the invention only requires a reaction zone temperature above the melting point of the highest melting component of the material being processed it is preferred to have a temperature at least above the vaporization point of the lowest vaporizing component of the material to enable a relatively short residence time in the reaction zone and consequently to enable processing of large quantities of powders conveniently the means for achieving such high temperatures can be any of several commercially available types but a plasma flame reactor has been found to be convenient due to its temperature capabilities its atmosphere flexibility and simplicity details of the principles and operation of such plasma flame reactors are well known and thus are not a necessary part of this description commercially available plasma flame reactors are equipped with powder feeding means some of which rely upon gas entrainment and these have been found satisfactory for the practice of the invention of course it is unnecessary that all particles melt completely since melting of the outer layer.