US2349637A

US2349637A - Froth flotation

Info

Publication number: US2349637A
Application number: US422103A
Authority: US
Inventors: Ruckwardt Kurt Felix
Original assignee: Anaconda Copper Mining Co
Current assignee: Anaconda Copper Mining Co
Priority date: 1941-12-08
Filing date: 1941-12-08
Publication date: 1944-05-23
Anticipated expiration: 1961-05-23

Description

Paiented May 23, 1944 FROTH FLOTATION Kurt Felix Ruckwardt. Anaconda, Mont, as-

signor to Anaconda Copper Mining Company, a

corporation of Montana No Drawing. Application December 8, 1941,

Serial No. 422,103

8Claims. (claw- 16s This invention relates to froth flotation, and has for its principal object to provide an improved method for separating a copper sulphide from a lead sulphide by selective froth flotation.

Many zinc-lead sulphide ores contain copper sulphides, and many copper sulphide ores contain lead sulphides. It is common practice to separate zinc and lead sulphide minerals'by selective froth flotation, making a lead concentrate low in zinc and a zinc concentrate low in lead When copper sulphides are present there is a decided tendency for th. copper to follow the lead. In the flotation of copper sulphide ores, lead sulphides, if present, follow the copper.

Copper in lead concentrate is undesirable in lead smelting, and a custom lead smelter will pay very little for the copper in alead concentrate. Lead in a copper concentrate likewise laundesirable, as it largely goes into fume and dust in smelting. for the most part cast into anodes for electrolytic refining, and such anodes should not contain much lead. i

I have discovered that if an aqueous pulp containing a mixture of lead sulphides and copper sulphides is conditioned with a soluble phosphate, and the conditioned pulp is then subjected to a froth flotation operation in the presence of a sulphide mineral collecting agent, the

Smelter-produced copper is bulk of the copper sulphide will float away from v the bulk of the lead sulphidef The soluble phosphate appears to depress the lead sulp de Selec'tively, leaving the copper sulphide fre to be floated; This effect probably is due to the formation of a minute lead phosphate film in the surface of the lead sulphide particles.

Based onthis discovery, the present invention provides an improved method for separating a copper sulphide from a lead sulphide by selective froth flotation which comprises treating above about 8.0, and advantageously between about 8 and 9. v

-It is preferable to condition the pulp with the soluble phosphate for a period of several minutes before adjusting the pH and subjecting the pulp to the flotation operation.

My investigations indicate that any soluble phosphate is suitable for conditioning the pulp preparatory to the selective flotation operation. A superphosphate fertilizer,- such, for example, as a treble superphosphate fertilizer, however, is a particularly economical and convenient source of a soluble phosphate for conditioning the pulp. 1

The new method may be carried out as a single flotation operation resulting in production of a flotation concentrate containing the bulk .of the copper and a flotation tailing containing the bulk of the lead. Generally, however, it is best to employ separate rougher and cleaner flotation operations. In such operations,

the pulp, after conditioning with the soluble phosphate, and preferably after being made alkaline, is subjected to a rougher froth flotation operation in the presence of a sulphide mineral collecting agent to produce a tailing containing the bulk of the lead sulphide with but little of the copper sulphide and a concentrate contain-f ing the bulk of the copper sulphide with some lead sulphide. The concentrate so produced is then advantageously conditioned with a further quantity of a soluble phosphate and is subjected to a cleaner froth flotation operation, again in the presence of a sulphide mineral collecting agent, thus producing a cleaner concentrate containing the bulk of the copper sulphide with but little of the lead sulphide; and a tailing containlng much of the lead that accompanied the an aqueous pulp of the mixed copper and lead sulphides with a soluble phosphate, and subjecting the thus treated pulp to a froth flotation operation in the presence-of a sulphide mineral collecting agent, whereby the bulk of th copper the bulkof the lead sulphide.

Preferably the pulpis rendered slightly alkaline after treatment with the soluble phosphate and before subjecting it to the flotation operation. 'Ijhis is conveniently, accomplished by rougher concentrate. The cleaner tailing may be returned to the rougher flotation cell for further treatment.

The-new method may be applied directly to crushed run-of-mine ores containing copper sulphides and lead sulphides. Preferably, however, the ore is first subjected to a conventional froth flotation operation to reject the bulk of the p sulphide in the pulp is selectively floa ed from gangue and to produce a concentrate containing the lead and copper sulphide values. The new method advantageously is applied to the treatadding lime to the phosphate-treated pulp, The pulp preferably is rendered alkaline to a pH ment of the concentrate thus obtained.

In carrying out the new method, the leadcopper concentrate or other material to be treated is incorporated in an aqueous pulp in the usual manner for conducting froth flotation operations. A quantity of a water-soluble phosphate is added to the pulp. A water-soluble superphosphate fertilizer, such, for example, as a treble superphosphate fertilizer, is a particularly convenient and inexpensive form of soluble phosphate to employ. However, any other water-soluble phosphate may be employed. The

' method has been carried out successfully using such water-soluble phosphates as phosphoric acid, ammonium phosphate, mono-sodium phosphate, mono-calcium phosphate, and di-sodium phosphate. Generally speaking, about 3 to pounds of thewater-soluble phosphate per ton of mixed sulphides in the .pulp i employedin the conditioning step.

Preferably the pulp is conditioned for a period of several minutes with the soluble phosphate. This is accomplished by adding the soluble phosphate to the pulp and holding the pulp for a conditioning period of several minutes before subjecting it to further treatment.

The phosphate-conditioned pulp preferably is rendered slightly alkaline before it is subjected to the flotation operation. The pH of the pulp should be adjusted to a value above about 8.0,-

advantageously between 8 and 9, after conditioning with the soluble phosphate and before subjecting to the flotation operation. It is usually most economical to render the pulp alkaline to the desired pH by the addition of an appropriate quantity of lime. However, other alkaline agents 1 (such, for example, as caustic soda) may be used addition of suiiicient collecting agent and with suflicient agitation and aeration to insure flotaadded. These include a frothing' agent and a collecting agent. Any of the well known frothing agents and any of the common sulphide mineral collecting agents may be used. For example, the frothing agent may be pine oil or one of the many available proprietary frothing agents, such, for

the trade as Du Pont 3-23" frother. The collecting agent may be any of the known sulphide mineral collecting agents used. in frothing copexample, as the product manufactured by E. I.- -du Pont de Nemours & Company and known to per sulphide ores, such, for example, as a' xanthate. Very satisfactory results have been obtained using sodium ethyl xanthate as the collecting agent, although the invention is not 1 limited to the use of this or any other particular in the froth, whereas the bulk of the lead sulphide is depressed and is withdrawn as the cell tailing. The tailings thus constitute the lead concentrate, and the floated product is the copper concentrate.

In order to. producea lead concentrate containing but little copp r, the first or rougher flotation operation may be conducted with the tion of.virtually all of the copper sulphide. Such operation will unavoidably cause some of the lead soluble phosphate and may be subjected to a sec-' 0nd or cleaner flotation ,operation to secure a more complete separation of the copper sulphide from the lead sulphide. Usually sufficient of the frothing and collecting agents remain in the rougher concentrate so that very little or none of these reagents need be addedto the pulp for the cleaner operation. The floated concentrate from the cleaner flotation operation may constitute the flnal copper concentrate, and the tailings from the second or cleaner flotation cell may be discarded as the tailings of the process, or may be returned for retreatment in the flrst or rougher flotation cell for the recovery of the lead and copper which it contains. Any desired number of flotations intermediate the first rougher operation and the flnal cleaner operation may of course be employed.

The following examples illustrate the eiIectiveness of the new process: I

EzampZe IP-An ore concentrate containing a mixture of lead and copper sulphides, assaying 54.96% lead and 10.33% copper, was ground and incorporated in an aqueous pulp for froth flotation. A commercial mono-calcium phosphate fertilizer was added ,to the pulp in the amount of six pounds per ton (the expression pounds per ton as used herein refers to the weight of reagent in pounds for each ton of sulphides in the pulp), and the pulp was allowed to condition in the presence of the phosphate for a period of five minutes. At the end of this conditioning period, sufficient lime was added to raise the pH of the pulp to about 8.6 to 9.0. The pulp was flotation operation in the presence of a frothing agent and a sulphidemineral collecting agent (sodium ethyl xanthate in the amount of 0.1 pound per ton was employed as the collecting agent). The tailing from this flotation operation constituted the lead concentrate. The floated product from this. operation (also in the form of a flotation pulp) was treated with two pounds per ton of the mono-calcium phosphate fertilizer and 0.5 pound per ton of sodium silicate, and-the thus treated pulp was subjected to a cleaner flotation operation. The concentrate from this flotation operation constituted the final copper concentrate. The results obtained are set forth in the following table:

Table I Recovery weight Cu Pb CI! -Pb PereentPermltPcreentPianl 10-35 54. 100.0 1. 1m 78.1 8-4 21-45 23.7 78.4 1- ms 04.1 13.: n.

Example -2.An ore concentrate containinga mixture of copper and lead sulphides, assaying v tioned pulp was subjected to a rougher froth 54.41% lead and 10.44% copper, was conditioned for five minutes with the addition of nine pounds per ton of a commercial monocalcium phosphate fertilizer. After this conditioning period, the pH of the pulp was adjusted to 8.6 to 9.0 by the addition of burnt lime. The pulp was then subjected to a rougher froth flotation operation, using 0.175 pounds per ton of sodium ethyl xanthate as the collecting agent. The tailing from the rougher operation constituted the lead concentrate. The floated product was treated with 1.5 pounds per ton of the mono-calcium phosphate and was sub-1 jected to a first cleaner froth flotation operation. The concentrate from this operation was again treatedwith 1.5 pounds perton of mono-calcium phosphate, and subjected to a second cleaner froth flotation operation, with the addition of frothing agent as required. The concentrate from the second cleaner operation constituted the final copper concentrate. The tailings from the two cleaner operations were combined as the cleaner tailing. The results obtained are set forth in the following table:

' Table II g Recovery Weight Cu Pb I Cu Pb Per cent Per cent Per cent Per cm! Per c 100.0 10.44 54.41 100.0 100.0 36.7 1.29 79.8 4.6 53.8 Copper concentrate. 38.0 2160 17.2 85.6 12.0 Cleaner tail. 25.3 4.08 73.5 9.9 34.2

I claim:

1. The method of separating a copper sulphide from a lead sulphide by selective froth flotation which comprises treating an alkaline aqueous pulp of the mixed copper-and lead sulphides with a soluble phosphate, rendering the thus treated pulp slightly alkaline, and subjecting the alkaline pulp to a froth flotation operation in the presence of a copper sulphide collecting agent comprising a xanthate' and selectively floating the bulk of the copper sulphide in the pulp from the bulk of the lead sulphide.

2. The method of separating a copper sulphide from a lead sulphide by selectlvefroth flotation which comprises adding a soluble phosphate to an aqueous pulp of the mixed copper and lead sulphides, rendering the pulp alkaline to a pH higher than about 8.0, and subjecting the alkaline pulp to a froth flotation operation in'the presenceof a copper sulphide collecting agent comprising a xanthate and selectively floating the bulk of the copper sulphide in the'pulp from the bulk of the lead sulphide.

.3. The method of separating a copper sulphide from a lead sulphide by selective froth flotation which comprises conditioning an aqueous pulp containing the mixed copper and lead sulphides with a. soluble phosphate for a period of several utes, then rendering the pulpslightly alkaline, and subjecting the alkaline pulp to a froth flotation operation in the presence of a copper sulphide collecting ent comprising a xanthate -'1: selectively floating the bulk of the: copper sulphide'in the. pulp from the bulk of the lead sulphide.

4. The method of separating a copper sulphide from a leadsulphide by selective froth flotation which comprises conditioning an aqueous pulp containing the mixed copper and lead sulphides with a soluble phosphate for a period of several minutes, then rendering the pulp alkaline to a pH of about 8 to 9, and subjecting the alkaline pulp to a froth flotation operation in the presence of a copper sulphide collecting agent comprising a xantha-te and selectively floating the bulk of me copper sulphide in the pulp from the bulk of the lead sulphide.

5. The method of separating a copper sulphide from a lead sulphide by selective froth flotation which comprises treating an aqueous pulp of the mixed copper and lead sulphides with a soluble phosphate, adding lime to the thus treated pulp to render it alkaline to a pH higher than about 8.0, andlsubjecting the alkaline pulp to a 'f-roth flotation operation in the presence of a xanthate collecting agent and selectively floating the bulk of the copper sulphide in the pulp from. the bulk of the lead sulphide. a

6. The method .of separating a copper sulphide from a lead sulphide by selective froth flotation which comprises treating an aqueous pulp of the mixed copper and lead sulphides with a superphosphate, rendering the thus treated pulp slightly alkaline, and subjecting the alkaline pulp to a froth flotation operation in the presence of a xanthate collecting agent and selectively floating the bulk of" the copper sulphide in the pulp from the bulk of the lead sulphide.

- aqueous pulp containing the mixed copper and tively floating the bulk of the. copper sulphide ln' the pulp from the bulk of the lead sulphide.

lead minerals with about 3 11015 pounds of a superphosphate per ton of mixed sulphides for a period of several minutes, rendering the pulp alkaline with lime to a pH of about 8 to 9, and subjecting the alkaline pulp to a froth flotation operation in the presence of a copper sulphide collecting agent comprising a xanthate and selec- 8. The method of separating a copper sulphide from alead sulphide by selective froth flotation which comprises treating an aqueous pulp of the mixed copper and lead sulphides with a soluble .phosphate, rendering the thus treated pulp slightly alkaline, subjecting the alkaline pulp to a'igougher froth flotation operation in the presence of a xanthate collecting agent and selectively floating a tailing containing the bulk of the lead sulphid'e with but little of the copper sulphide and 'a concentrate containing the bulk of the copper sulphide together with some of the lead sulphide, treating said concentrate with a further quantity of a soluble phosphate, and subjecting the thus treated concentrate to a cleaner froth flotation operation in the presence ,of a xanthate collecting agent and selectively floatin a concentrate containing the bulk of the copper sulphide with but little lead sulphide.

KURT FEHX RUCKWARDT.