| Show low grade lead ores of utah bulletin innovations in the metallurgy of lead by dorsey A lyon and oliver C ralston has just been issued by the bureau of mines department of the interior this bulletin discusses the subject of the treatment of lead ores by other than the ordinary metallurgical processes which areat are at the present time applied for the recovery of the metal values from such ores As is well known one of the principal functions of the bureau of mines is wherever possible to devise ways and means of preventing waste of the count rys mineral resources in connection with mining and metallurgical work it is for this reason that the work of the bureaus station at salt sal t lake city has been devoted largely to the problem of extracting the values from the large bodies of ores which occur in utah and the adjoining states and which are too low grade to permit of their being treated by present day metallurgical processes without previous concentration As a rule these low grade ores cannot be concentrated by ordinary gravity concentration processes or even by the flotation process due to their chemical and physical nature these ores may be grouped as follows 1 and non lead carbonate ores 2 complex ores of lead and zinc containing other metals 3 slimes from concentrators treating lead sulphide ores flotation has recently done much toward the solution of the last mentioned problem As for the ores of class 1 namely the and non lead carbonate ores the low grade ores of this class are very difficult to concentrate by gravity concentration processes because the lead silver minerals slime very readily causing excessive losses in the mill slimes when the oxidized ores can be treated by dazing followed by flotation the problem of treating this class of ores becomes a comparatively ively simple one but when they contain elements that make impossible resort must be had to some other method of treatment and so the bureau has made a study of the possibility of devising or metallurgical pyro processes which it would be commercially feasible to apply to ores of this class the work on processes which the bureau has done for the recovery of lead from oxidized ores has been based upon the solubility of lead chloride and lead sulphate in neutral saturated brine solutions and the solubility of lead carbonates and oxides in acidified acidifier saturated brine solutions lut ions from these solutions the lead may be precipitated by means of the electric current or by slacked lime the product resulting from the precipitation by electrolysis is sponge lead and that from the lime precipitation is a complex lead hydroxide the bulletin gives the details of the experimental peri mental work which was carried out along this line discusses the chemistry of brine leaching in general and states the conclusions that were drawn from a very extensive series of tests of leaching and electrolysis it also discusses the subjects of roasting followed by brine leaching volatilization of lead from oxidized ores of oxidized lead ores containing gold and silver and flotation of lead carbonate ores and the possibility of applying such methods commercially the general conclusions of the authors as regards the work which has been done by the bureau on lead ores are 1 it is possible to recover at a profit by the application of hydro metallurgical and other processes not at present commonly used depending upon existing conditions the metal values contained in oxidized and A complex lead sulphide ores 2 both a neutral or acid saturated brine solution will dissolve lead sulphate or chloride 3 when the solutions are pure the lead may be precipitated with lime but when they are impure they should be precipitated with the electric current 4 the metal values may be obtained from oxidized lead ores by either one of the three following methods followed by flotation the acid brine leaching of the raw ore and volatilization of the lead with salt and heat 5 when silver and golbare gold gol dare are present in the ores the best treatment is by ing and volatilizing part of the lead followed by the leaching of the remainder from the calcines 6 lead can often be recovered from carbonate ores by followed by flotation the same ores can be worked for their lead values by volatilization 7 simple sulphide ores can be treated by volatilization or sulphate roasting fol bowed by brine leaching 8 lead can be recovered from zinc lead sulphide concentrates without changing the zinc sulphide by volatilization of the lead and precipitating the metal from the resulting fume in an electrical precipitator 9 lead can be recovered from lead iron by the volatilization n method just mentioned this process will give low silver recoveries 10 lead can be extracted from a complex sulphide of lead zinc zin C copper iron gold and silver by and volatilization the lead separation is good the remaining metals cart can be recovered from the calcines or iron by flotation 11 there is a possibility that the furne fume from bag houses might be handled very well by one of the methods just mentioned in the authors believe that a study of the costs of the methods discussed by owners of properties to which such processes could be advantageously applied should result in their being given semi commercial tests due to the fact that practically all of the pro besses mentioned give high recoveries of the metal values and produce metallic lead the adoption of such processes would permit of the treatment of lead ores which at the present time are too low grade to ship and which can not be concentrated into a high grade product due to the chemical and physical nature of the ores moreover any process which will produce the metal at the mine and which is commercially feasible should be acceptable to the operator due to the fact that it permits him to ship bullion and thus thu eliminate the freight charges on a large amount of worthless gangue material where the ore has to be shipped a long distance for metallurgical treatment |
