US1402740A - Process of treating ore - Google Patents

Description

STA E PATENT OFFICE.

- ma mum? commas, or SAN rmcrscdcamrom rnocnss or rnnarme can inoateo;

Ho Drawing.

T 0 all whom it may, concern:

Be it known that I, MAY Knrmrr Connnis,

a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented certainnew and useful Improvements in Processes of Treating Ore, of which the following is a specificatiom This invention relates to. processes of treating ore, and it comprises amethod of assisting in recovering the values of various nietalliferous ores wherein such ores in a ,raw finely divided or powdered condition are vigorously agitated for 'atime with water containing small amounts of a'dissolved neutral salt, I such salt being. advantageously sodium nitrate, and also containing an alkali or an alkaline reacting body,- the agitation being continued sufficiently long v to permit thorough action by the solutes of said solution upon the fine particles of ore pausing various changes in saidparticles, and. the values are then recovered by a process involving gravital separation of-said particles; and it comprises a. method of making gold ores amenable to amalgamation wherein such a gold ore in a finely 'divid'ed state is vi'gorougly agitated'at the or .dina-ry temperature fora time with a dilute solution containing an oxidizing salt, such salt being advantageously sodium nitrate,

' all as more fully hereinafter set forth and and a basic salt, such salt being advantageously sodium or potassium carbonate and is treated to amalgamate the contained gold, the amalgamation treatment being simultaneous or subsequent tosaid agitating;

as claimed.

Metallic ores may contain any one of very many substances; and, as a, rule they are rather complicated, being composed of many I contain sulfids;

minerals ingreater or less amount. In ad 'dltion .to the ore mlnerals themselves, all

ores contain more or less gangue mineral.

Most ores contain silica or silicates; many and some. contam free metals. Inordinary methods of concentration it is usual preliminarily to grind the ore and assoclated gangue to a finely powdered, condition; to grind to convert the ore into the so called pulp. With many;

ores the fineness of grinding may be as great as 800 to 100 mesh; that is the ore is so finely ground that all of it will go through an 80 mesh screen or-100 mesh screen as the case may be. But in such fine grinding of course very many of the particles are much Specification of Letters Patent. P t t J 10, 22;

Application filed December 1, 1919. Serial No. 341,586.

the coarsest particles will go through an 80 mesh sieve." Even with much coarser grinding, as to 20, 40' and mesh, a very large proportion of the particlesare impalpably.

fine; of a fineness approaching that of the particlesof ordinary clay. The ore minerals, as a rule, are more frangible and brittle than the gangue particles or silicates and they crush finer; pulped ore is mixed with water and sub? jected to a gravital separation of one land or another. Whether this separation be on tables'or any of the very many other types of apparatus in use the principle is the same as settling in a vat; the particles of greater specific gravity goto the bottom first while those of less specific gravity or density reach the bottom afterwards. In amalgamatin gold ores'the principle is much the same but the heavier gold particles are caught by mercury. In practically In concentration the all methods. of concentration, including" amalgamation as a concentrationmethod for the present purposes, the efl'ort is to separate heavy fine particles from light fine particles by taking-advantage of their diflerential settling in ,water. v. I i

In this-separation however the difficulty is experienced that the relation of the various particles to water is not the same; Irre- 'spective of specific gravity 'or' density, some particles have a greater tendency to stay in suspension in Water than haveothers; Ordinary clay, which is a component of very many ores,v for example, in its ordinary natural or raw state, has agreater tendency to stay in suspension lnpure water than have other minerals; even than some which are lighter in density; but this tendency is profoundly influenced by even traces.

and containing the 'OH ion tend to keep a it in suspension. Most finely ground silicates, as well as silica itself, tend to act more or lessilike clay; the tendencybeing the greater the finer: the subdivision and the nearer the. particles approachlclay. particles in size. On the other hand, the characteristic ore minerals, sulfids, free metals,

etc., inthe. presence of water all behave quite difi'erently from clay even when in a the electrolytes, make differences in the away the particles 'settleout of" a suspension.-

. Most earthy materials and many ores con 1o tain enough soluble matter to affect gravital separation methods more or less; and some- ,times this influence is in the Tdirection of promoting a clean separation and some;

imes" not.' 115.

In thelpresentinvention I utilizethese "facts. -I have discovered that in recovering .the values of nearly all metalliferous ores in s practicallyany gravital separation it is of. "advantage tofefi'ect preliminaryphysical .(or physical and chemical) changesin the ore particlesby electrolytes inorder to at- "..neutral salt.

feet their relation to water; th'at is the.- relations bywhich'they' tend to' stay sus-- pended or not to, stay suspended as the case may be; In so doing it is commonly advan--. .tageous' to employ both classes of electrolytes, the neutral and the alkaline, in order to effect differential changes. in the various classes of particles. As the neutral-'elecg trolyte I may use sodium nitrate, sodium chlorid, sodium sulfate or any other soluble As the alkaline electrolyte jwhile I" may employ caustic alkali'es yet since'these' quickly become carbonated, 1t

isgenerallybetter to use sodium carbonate "(sal soda, sodaash, etc.) or potassium car bonate directly.

As stated, ina, measure, as regards at least some ofthe'fine-particled component of an ore, such as'clay, these two materials have opposite effects; Taking salt and sodium carbonate, for-"example, in solution in'water containing clay, the salt willtend '1 'ing effect of the neutral electrolyte is pre to precipitate the clay while the sodium carbonate tends to keep it in suspension,

Both efi'ect changes in the physical structure of the clay particles corresponding to thesepalterations in the. behavior the par 'ticles exhibit towards water. Whether itbe for the reason that thesuspension-favoring tendency of the alkaline electrolyte is predominantly exhibited on the gangue or silicate particles while the suspension-breakdominantly exhibited'towards ore minerals,

sulfids, native metals, etc. 'or for some other reason ZI findthat the conjoint; influence of these two materials on cite mixtures, favors carrying down 'heavy nietals and heavy metal compounds to the bottom whilekeepmg light metal compounds (silicates and the like) in' suspension. The net effect efiect. The'i tefiect of these electrolytes on 'ite and other tungsten minerals.

' anoaveo the physical consistency ot the ore particles velop even with fine particled oreand thoroug'h admixture. l find that as a rule vigorin the qaseot some refractory ores {l or.-5 hours are requisite prior to attemptlng any gravital separation. No high temperature 1 IS necessary or desirable l find 'it better to work at the ordinary temperature.

is not, instantaneous; it takes time to dea Many of the saline solutions which I employ may have chemical activity upon the .ore as hereinafter set forth, but they. have, the physical activityjust described. Insofaras the physical activity alone is concerned the solutions sufier no substantial change andthey may be repeatedly used on.succes- 1 sive batches ,of-ore being merely replenished sufliciently'to make up for losses. Taking inits usual gangues, I find that about 4") minutes agitation of the ore, groundto the the so-treate'd suspension on the tables in.

the case of ores which, Would'otherwise not separate well." The same is true of Wolfram- Thehig'her in sulfids the oreis, as a rule the longer the agitation should be continued in orderv to be certainof efi'ecting the'physireal changes in the particleswhich I desire. 'VVith such sulfid ores however the physical action may'be, and often is, attended by favoring c'hemlcal changesin the valuable minerals themselves. With longagitation in an electrolyte, electrolytic actions set up between the more electro-positive and the more electro-negative materials present, which mayyand often'do, set free or clean particles of the noble'metals, gold, silver,

mercury, platinum,,etc. In the case of ores .for example scheelite, or calcium tungstate rich in pyrites and containing gold,chemical action 'oftengoes so far that after the agitation not only are the auriferous parceptible of free amalgamation. The same is true ofmany silver ores. Injmany-embodiments of my invention treating ores of the precious or noble metals-I therefore contemplate 'amalgamating as' apart of my gravital treatment.

cury and can becollected "with the mercury.

I -lVith such'an ore, for example, on stamping favorsseparatlon. Any solubles which may be .in the ore; become immaterial in their it in'the ordinary stamp mill together with mercury and passlng the pulp over amalgamated tables, muchor most of the gold is ticles gravitally separable, but they are suscollected by the mercury. There are many tellurids, arsenids, and is of uno'xidized nature. These ores not being amenable to the ordinary amalgamation processes and apparatus they must betreated by various methods of more or less complicated nature in order to regain the gold.

In another application, Serial No. 141.298,

filed January 8, l 9 l7,-whereof the present,

case is a continuation, I have described a method of rendering such refractory ores amenable to amalgamation which in sub-- stance consists in agitatingzthe ore, during or prior to amalgamation, with a solution containing sodium nitrate and potassium p i be'employed n various ways'in'performmg carbonate.

-As to why'ag'itation with materials such I as these should facilitate amalgamation in the case'of refractory ores, I am unable tosay and can only give the result.- It is-p er haps due to electrolytic a'ction'with perhaps oxidation by the nitrate. Refractory ores treated'isreadily. amalgamated by-mercury.

"Any type of; stirring or-agitating apparatus always contain in addition to the gold which is'strongly. elect'ro-negative the stated sulfids, etc., which are electro-positive and readily undergo oxidation. The solutlonl of nitrate and carbonate conducts electricity freely andds adapted for forming couples vbetweenthe particles of 'the-metahand particles of the sulfids, etc. A. solutionof alkaline reaction, which is'imparte'd by the p05 .tassium carbonate, is capable of wetting sul- I fids, etc., better than a neutral solution or one of acid reaction. However, the-matters.

mentioned are theoretical. "lhe'actualre sult is that with the solution mentioned I amalgamation becomes ready.

I have. found that various other oxidizing salts than .the sodium nitratel'may be em ployed, as for instance potassium nitrate,

sodium or potassium chlorate,;h'yp0chlorite solutions, chromates, etc.; but I, have found 3 that the sodium nitrate in addition to its cheapness seems to exercise a much better action than the' other salts mentioned.

Similarly I have found-that sodium carbons ate may beysubsti'tuted for the potassium carbonate. But I find potassium carbonate to work the better.

It is possible and indeed probable from certain observations which I have madethat;

the'beneficial action 'of the electrolytic .bath

is not only exerted upon-the gold of the mineral but-that part of the benefit resides in'keeping the mercury clean-surfaced. In operating with the described bath in the presence of mercury which I regardas the best way of operating, the mercury 'does not tend to flour and remains clean-surfaced.

' the ore. No heating being required,- agita tion may be'eifected-inany ordinary glass beaker. Heating disturbs the actions which 'I wish to secure.

In making-the bath the best proportions I have found are about one part of commercial sodium nitrate or caliche, one: sixth part of commercial carbonate of potassiu'm of pearlasli-andthirty-twoparts of water.

In, using such a solut on or bath, it may the present process. v In one; wayof'operating, the ore reduced to a fineness of 80 mesh or finer is agitated with the solution at the rdinary temperature .for one to ten hours theexact length of-time: depending upon, the-characterof the ore. The, ore "so which islc'a'pable of producing thorough agiration with positive contact between all parts ofthe; ore and the solution may be employed." The type of agitatio'n'I desire is really a sort of churning action. After the agitationfthe solution may be removed from the ore"pul-pi and reused- Sometimes I find it necess'ary to treat it 'withadittle quicklime or slaked limetore'generate it more.

pr ces. It may be strengthened byiadditionof'- fresh chemicalsfi' The 'ore pulp'lmay be, washed and the washings used-in preparing fresh solutions. After the treatment the 0T6 pulpmay be amalgamated in any of" the usual ways, as forinstanc by flowing over theordinary amalgamate plates.

- A better method .offoperation' is afforded by havi-ng more or less mercury presentduring the agitation or churning. Ordi- -na'rily no flouringof the mercury is'to be feared.-

The mercury cleaning action of "the com- 'position describcdmay be used in treating amalgam platesand-the like or in preparing such plates. For example, a plate of pure soft copper rubbed with mercury in the' presence of the .stated bath, the'operation being repeated at intervals, say 5 times with intervals of 10 hours, gives a collecting plate of better character than a silver plate.

The solution is not. deteriorated by its contact with the ore constituents save insofar as sodium nitrate is reduced. This gives sodium carbonate. In such cases fresh sodium, nitrate may be addedfrom time to time.

I as a'result of reduction, itself develops more trolyte, for the present purposes; audit also furnishes loosely bound oxygen which much accelerates many of the electro-chemical actions heretofore mentioned. Chili saltpeter,

or less alkalinity so that with some ores I using Chilisaltpeter it is unnecessary to add an alkalineelectrolyte.

So far .as'the. physical results'are concerned however, I find that common fsalt with a little sodium carbonate or potasslum carbonate answers very well. Common sea salt usually containsenough alkaline material, or is susceptibleof furnishing such alkaline material. under the influence --of ores, t 'serv'e well forthe present purposes.

j I. In a specific embodiment 'of'the present invention treating a refractory gold ore containing pyrities, I may grind the ore to 80 or 100 mesh and stir violently from 3 to 'carbonate-isfurnished by the sodium nitrate 4' hours-With a solution of Chili saltpeter.

containing say 6 per cent ofsod-ium nitrate. About 0.25 to 0.50 .per cent of potassium carbonate is ordinarily a useful addition.

Sometimes it-is advantageous to use a little sodium carbonate as well althoughsodium itself under the influence-of reduction by the sulfids and the ,action of atmospheric carbon dioxid. The stirring should' be effective,- thoroughgoing and. drasticagitation; not merely a shaking together.

After the stirring is complete the mixture may be run through or over any-ordinary amalgamating deviceln the usual way. The

gold settles well and, because of the'action of the sodium nitrate, and the electrolytic actions which go -on between the particles of ore it is made clean surfaced and readily amalgamable.

For many purposes a solution of about 1- part of commercial-sodium nitrate or Chilisaltpeter and one-sixth partof commercial potassium. carbonate or pearlash dissolved in about 32 parts of water make a very good solution or bath, and especially for refractory gold ores .containing sulfids.

Sometimes it is desirable to add a little acid, or

acid reacting salt, such as alum, to themix ture. One very good composition-may ,be

made by dissolving 100 parts of commercial Chili saltpeter, 37.5 parts of commercial sal soda, 2 parts of commercialpotassium Gaff-"- b nate and one eigh'th part of ordinary alum in water sufficient to give a .5 or 6 percent solution. This composition is particularly gpod 1n treatlng mercury ores contain- .ing mercury in a sulfid form. The electrolyte has an actiontending toward the sepa-' ration of, metallic mercury from the sulfid. For some reason, and because. of some reaction not understood,-I havefound that vigorous. agitation of sulfid ores of mercury with a dilute-solution "ofYsodium nitrate,

and especially in the presence of a little carbonate, causes a separation of globules of metallic mercury.

This application is a consolidation of my application Serial No; 287,577, filedApril 4, 1919 and my application Serial No. 281,057, filed March 6,

What I claim is: 1

1. In the recovery of values from metallicores by differential gravity separation, the

process which includes. preliminarily vio; lently agltating such an ore in a finely powderedstate at the ordinary temperature with a solution containing a neutralelectrolyte continuation and.

and an alkalineelectrolyte for a time'sufficient to effect physical changes in the granules and thereafter gravitally separating.

2.- In the recovery of values from metallic ores v by differential gravity separation, the process. which includes preliminarily vio-' lently agitating such an ore in a finely pow-i dered state .at the ordinary temperature with a solution containing sodium nitrate. and an alkaline electrolyte for a time sufficientto effect physical changes in the granules and thereafter 'grav-itally separating.

3. In the recovery of values from metallic ores by differential gravity separation, the process which includes; preliminarily .violently agitating such an ore in a finely-powdered state at theordinary temperaturewith,

a solution containing sodium nitrate and potassium ea'rbonatefor a time sufliclent to effect physical changes "in the granules and.

thereafter gravitally separating;

4. The process of amalgamating metals which comprises agitating mercury and such metal in contact at theordinary temperature inthe presence of a bath containing sodium nitrate and potassium carbonate.

5 The process; of recovering metals from ores by amalgamation which comprises agi- I 'ta'ting an ore at-the ordinary temperature with me'rcury'in the presenceof a bath containing sodium nitrate and potasslum carbonate; s s a v 6. In the. treatment of. refractory gold :ores the process which comprises agitating such a gold ore at the ordinary temperature with. a dilute "solution containing an 'oxidiz ing electrolyte and-an-alkaline reacting salt. 5

'7. In the treatment'of refractory gold ores the process which comprises'agitating such an we at the ordinary temperature with a. dilute solution lcontaining sodium nitrate and potassium carbonate.

In testimony whereof,'I aflix my signature hereto.

MAY KRUMP coDDINe.