Cyanide Poisoning Antidote

In 1910, the Committee of the Chemical, Metallurgical and Mining Society of South Africa, appointed to investigate cyanide poisoning, recommend as an antidote to Cyanide Poisoning the following:

  1. Thirty cc of a 23 per cent, solution of ferrous sulphate.
  2. Thirty cc of a 5 per cent, solution of caustic potash.
  3. Two grams of powdered oxide of magnesium (light).

In every cyanide-room there should be kept three boxes, containing—

  1. A metal receptacle to hold about a pint, and a spoon.
  2. A blue hermetically sealed phial, containing 30 cc of a 33 per cent, solution of ferrous sulphate.
  3. A white phial, hermetically sealed, containing 30 cc of caustic potash.
  4. A packet of oxide of magnesium (light).

Preparation of Antidote

Quickly empty the contents of the blue phial, of the white phial, and of the magnesia package into the metal receptacle, and stir well with the spoon. This should be done as rapidly as possible, as the patient’s chance of life depends on promptness.

Administration of the Antidote

If the patient is conscious, make him swallow the mixture at once and lie down for a few minutes. If the patient is not conscious, place him on his back and pour the mixture down his throat in small quantities, if ….Read more

Agitated Cyanide Gold Leaching Test

In the old days laboratory tests were usually made by mechanically shaking up in a bottle for a given time a charge of ore and cyanide solution. The most generally convenient device for this purpose is a wheel, to which are attached boxes, each capable of containing a standard acid bottle, and with means for securing the bottle firmly in place. The wheel is rotated at about 30 r.p.m. by a belt driven off a line of shafting. Objections have been raised to this device on the ground that agitation in a stoppered bottle does not allow of a proper aeration of the charge. Such objections, while plausible, are not borne out by facts, actual experience showing that the aeration obtained in this form of agitation is amply sufficient for almost any ore. It is of course necessary to leave an adequate air volume in the bottle, and for this reason the charge should not more than 1/3 fill it. A useful form of agitating wheel is shown in Fig.

A form of bottle agitator devised by G. H. Clevenger is useful in some cases. It was designed to meet conditions where the ….Read more

Determine the Proper Grind Size for Gold Ore

determine_the_proper_grind_size_for_gold_oreWithout mineralogy, estimating the optimum Grind Size for Gold Ore Sample is most conveniently made by Laboratory Testing and the agitation leaching method, and it will be necessary to make up 3 or 4 bottle charges in order to have enough ore* for the subsequent screen analysis.

Take an average sample of the ore and grind on the bucking table to pass No. 30 sieve. Weigh up 4 lots of 300 grams each and place in 4 standard acid bottles, add to each the quantity of lime estimated from the alkali consumption test, and water in the ratio of 3:1. For addition of cyanide it is best to make up a concentrated cyanide solution and ascertain the strength by titration. The number of cc equivalent to a given weight of cyanide may then be run in to the charge of ore and water in the bottle from a burrette. The volume of liquor to be so added may be allowed for when diluting the pulp, so as to give the exact ratio of solution to ore originally decided on. It is usually advisable to shake up the bottle containing the ore water and lime ….Read more

Calculating Cyanide Consumption

Computing Cyanide Consumption of a laboratory leach test may be done as in the following example: Ore taken, 250 grams. Ratio of solution to ore, 3:1 = 750 cc: 250 grams. Cyanide strength, 0.3% KCN.

Calculating Cyanide Consumption

Or when working on the metric system,
Ore taken 200 grams,
ratio of solution to ore 3:1 = 600 cc: 200 grams,
cyanide strength 0.3% KCN

Estimating Cyanide Consumption Added

It should be noted that cyanide consumption as figured above represents chemical consumption only. In practice there will also be a mechanical loss of cyanide in residues, and also a loss to some extent in precipitation, if the zinc process be used. The mechanical loss in residues will depend on the strength of solution used, and also on whether the slime residue is dewatered by a filter or by decantation.

In the case of silver ores the chemical consumption indicated in a bottle test usually corresponds very closely with the actual total consumption to be expected in practice, and for this reason; an important factor in the cyanide consumption is the amount that combines with the silver: on precipitation this silver is replaced by zinc, ….Read more

Cleaning & Melting Gold Precipitate

With zinc shaving precipitation the usual method of cleanup is to shut off the flow of solution and starting at the head compartment of a box to wash the shavings gently in the solution avoiding any action that would tend to break up the attenuated threads into short pieces. The zinc is then removed and after draining may be placed in a tub of water to protect it from oxidation by the atmosphere. A plug or cock is then opened at the bottom of the compartment and the solution, sludge, and short zinc allowed to run out into a launder which conveys it to the clean-up tank. The interior of the compartment is then carefully hosed out and cleansed with brushes or sponges, the outlet closed, and the screen-bottomed tray replaced. The long zinc is removed from the tub of water and carefully packed in, and the next compartment proceeded with in a similar manner, the shortage of zinc in the first being supplied by that removed from the second, and so on down the line. As soon as each compartment is cleaned and repacked the solution flow is opened and allowed to run long enough to cover the zinc ….Read more

How Arsenic, Antimony Silver Compounds Affects Leaching

Ores containing silver in Arsenic and Antimony combinations offer considerable difficulties in cyanidation and it has usually been considered that the removal of these compounds by concentration was the only way to deal with them. G. H. Clevenger, however, when working on the ores of the Nipissing Mining Company of Ontario, Canada, found that by grinding exceedingly fine and treating with strong solution for four or five days a high extraction could be obtained. The silver occurred partly as sulphide, sulphantimonide and sulpharsenide and partly as metallic silver and dyscrasite, an alloy of silver and antimony in varying proportions.

To accelerate the dissolution of the antimony and arsenic compounds J. J. Denny introduced a process that had for its object their decomposition in a preliminary treatment. This process consists in grinding the whole of the ore to a slime and subjecting it to the action of metallic aluminium in a caustic soda solution, after which it is filtered and subjected to cyanidation.

By the preliminary treatment the silver, and in part at least, the antimony and arsenic, are reduced to the metallic state, and are so found. The reduction is accomplished by the nascent hydrogen resulting ….Read more

Sulphide concentrate leaching

The question as to whether concentration shall be included in the treatment of a given ore will often depend on the possibility or otherwise of recovering the precious metals from the concentrate at the mine. It may be suggested that if the concentrate can be cyanided after being separated from the gangue, why can it not be equally well cyanided if allowed to remain in the pulp going to the cyanide plant? The answer is that a small bulk of refractory high grade material can be treated by special methods which would not pay if applied to the whole of the ore. For instance, a few tons a day may be profitably roasted or slimed or treated with extra strong solution or for extra long periods, all of which might be prohibitive if applied to the entire ore.

There are two ways of dealing with a concentrate in a cyanide mill; one is to regrind to the degree of fineness found to be necessary by experiment and then to discharge the resulting pulp into the stream of mill pulp flowing to the cyanide plant, where the mixture goes through the usual routine of the process; and the other is to ….Read more

Effect of Manganese on Silver Leaching

In Mexico and elsewhere there are large bodies of valuable silver ore containing manganese which present great, and hitherto insuperable, obstacles to a satisfactory extraction by cyanide. The proportion of the silver that is soluble in cyanide varies greatly and may be as low as 5% only. The mere presence of manganese in the ore is not invariably accompanied by refractoriness of the silver because the writer has known of an instance where ores of apparently similar composition and character and coming from adjacent mines behaved quite differently, one yielding only 50% of its silver and the other 90% under the same conditions. As a general rule, however, when oxides of manganese are present in a silver ore trouble may confidently be expected.manganese

The manganese usually occurs as the dioxide but in what way, if at all, it is associated with the silver has never been determined. There are three possible theories on the subject. The first is that the refractory silver occurs as a silver-manganese mineral. Although no such mineral is described in the text books, there are certain facts which would seem to point to its existence:

(a) The silver is ….Read more

How Arsenic Affects Cyanidation Leaching of Gold

The Influence of Arsenic in the Cyanidation of Gold Ores is explained by W. B. Blyth has he is of the opinion that the presence of arsenic in an ore does not necessarily cause that ore to be refractory to cyanide treatment. He thinks the idea arose from the fact that arsenic is so often accompanied by antimony, pyrrhotite or graphite, stating that “the two former minerals cause premature precipitation of the gold almost as fast as it goes into solution, if they are present in sufficient quantity.”

The trouble in cyaniding semi-oxidized ores of arsenic he attributes rather to the presence of acid ferrous salts, and if he is right a preliminary water wash or possibly a weak acid wash ought to meet the case. (It should be noted here that the paper referred to does not deal with the cyanidation of silver ores containing arsenic.)

In detailing a number of experiments made on a certain antimonial gold ore Mr. Blyth states that by milling in water and running the ore into dams where it was settled, dried, and allowed to oxidize by cultivation of the surface, the pulp changed in color from a dark grey to a light ….Read more

Metallurgy for Recovering Gold from Telluride Ore

Gold ore associated with Telluride is hardly soluble in ordinary cyanide solutions and special treatment is necessary for its extraction. There are two methods in use in such cases.


The ore is ground dry to about 30 mesh and roasted; it is then ground to a slime in water or cyanide solution, usually in grinding pans, utilizing the opportunity simultaneously to amalgamate any gold that may be amenable, and finally treated by agitation in cyanide solution in the ordinary way.

Treating Raw with Bromocyanide

This process was used at the Deloro mine, Ontario, Canada, on a mispickel ore, and was developed in Australia by Dr. Diehl for the treatment of the sulpho-telluride ores of the Kalgurli district. The process essentially consists of grinding exceedingly fine, and then agitating with cyanide solution to which bromide of cyanogen is added at intervals. In some mills preliminary amalgamation and concentration are in use, the concentrate being roasted and then cyanided. During bromocyanide treatment the protective alkalinity is kept at the lowest possible point owing to the instability of the reagent, lime sufficient for settlement being added after the treatment is finished.

Julian and Smart state that at Kalgoorli when dealing with slimes assaying from 1 to 3 ….Read more

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