The Ashburton Guardian. Magna est Veritas et Prævalebit. THUESDAY, FEBRUARY 23, 1888. REFRACTORY ORES.

Ashburton Guardian, Volume VII, Issue 1774, 23 February 1888, Page 2

The Ashburton Guardian. Magna est Veritas et Prævalebit. THUESDAY, FEBRUARY 23, 1888. REFRACTORY ORES.

On the 11th instant, m the course of an article on the mineral resources of the colony, we alluded to the fact that New Zealand possesses large quantities' of refractory ores, the successful reduction of which would give an immense impetus to our mining industry, and urged thattbe Mines Department should send one ef. its officers to America for the purpose of making himself acquainted with the methods thero employed, and bringing back the knowledge for the benefit of .New Zealand miners. Since wo wrote this there has come to hand a batch of Parliamentary papers among which is a report of the Goldfields and Mines Committee, which contains very valuable information on the same subject and flluy boars out the views wo odvanced. At p 9of the report m question will be found the evidence on this very subject of Mr Gordon, Inspecting Engineer of the Mines Department, who says: — "I think the colony wants information upon the following subjects : The best methods of treating the various classes of auriferous and argentiferous ores, their reduction by machinery, tho best kinds of amalgamating machinery, the mode of working the lixiviation process, and with respect to the chemicals generolly used m amalgamating pans, the various modes of working lodes ; also information relative to hauUng and pumping machinery, and on the ventilation of mines. First, with reference to the treatment of auriferous and argentiferous ores, the chief subject that will have to be considered is some cheap, simple, and effective method of treating such ores. Wo have largo lodes of ores m New Zealand of low grade, but at tho present time they are valueless, because the mode of treatment is too costly and they will not pay for the working. Not only is the treatment too costly, but wo do not get anything like a fair percentage of motal from the ores. This applies m a greater degree to the Thames district, also to Te Avoha and Coromandel districts, rather than to the southern, goldfields. On tho southern goldfields the gold is m a more free state, and not so much combined with other metals. Rut m the Thames, To .Aroba, and Waihi districts a good many ores are very refactory, containing sulphides, selenidcs, tollurides, and chlorides ; there aro also cinnabar, galena, sulphur, and arsenic, all m the same lode. It is well known that these sulphide ores are also m many instances arsenious, and working theso by the , ordinary battery process has an injurious effect upon tho quicksilver, as sulphur and arsenic destroy its affinity for the precious metals. £0 long as gold and

silver aro associated with sulphur or arsenic, the sulphur, being .bo; .light carries off thd gbjd'v^i.th it .j ;3ve|i after;' running througb/a serjea o|teettl|nVpits, you will find the sulphur oWrry away the gold. Tho character of the gold at tho Thames, likewise, is different from that found m any other part of the Australasian Colonies ; it is so finely divided, combined with silver, and so thickly disseminated through the stone, that there is not m the Australasian Colonies,, so far as I am aware, anything to be compared to it. lam thoroughly convinced, from what I have seen of the modes of treatment on tho Northern Goldfields, that, by tho ordinary stamper I proccsg which is now m existence, if an average yield were to bo taken, they do not get over 33 per cent of the metal that tho ore contains." This, it will be seen, means a loss of G7 per cent, over two-thirds, of tlu gold, and that this is the iact Mr Gordon adduces proof m what has occurred at To Arnha. There, he says, " they found that when the stone from the New Find Claim, when it was first opened, was crushed by the stampers, it contained about 2oz to the ton. The tailings were subsequently treated m berdans, and they gave close on a similar amount ; and finally they were put through bcidans a third time, and found sufficient gold m them to pay : so that, (he adds) m many instances, I feel certain, they do not get anything like 33 per cent." The main fact ( says Mr Gordon) wo have "to contend with m New Zealand is having a small field m comparison to the Australian colonies, and much more so m comparison with America, which turns out about six times as much gold and silver as the whole of the Australasian colonies put together. We have not sufficient capital to experimentalize on the treatment of our ores as they have on those large goldfields, or to erect plant.l 3 suitable for the treatment of ores. Although we may now and then, by testing small samples, be able to extract the gold from its matrix ; still, when the metal coiurs out, it is found at timos that the cost of the treatment is more than the ore itself is worth. What wo want is some effective way of treating low -grade ores. I believe that the best way of dealing with the difficulty and the way most beneficial to the colony, will bo by obtaining the best information that can be got on all these questions And the beat vray of obtaining that information, m my opinion, is to send some one thoroughly acquainted with New Zealand and its ores to visit Amcvicn, where mining is carried on on such an extensive scale, so that he may see the principles adopted thorc. He would be able to see whether such processes as are a'lojted there could bo carried on m New Zealand with advantage 'J here is no doubt

that a person living m one locality gels into a particular groove of working. I think that a person who has travelled and seen tho various modcß* m which different classes of mining is carried on, il he is a practical man, will be likely to form a sound judgment, and will probably be ablo to discover improved methods of working our loads to better o<lvnnt.ojrj~ tl>on ■aro worlr fhom mt.-jw sent. I think also that, along with tliis, he would be likely to observe the improved methods of haulage and pumping that are adopted, and the best means of vcutilation m mineß* He would not only see all these things on the spot where they are m full work, but he would be able to bring back plans carefully made of tho improvements he had observed m America, which could be ndapted to mining-work m New Zealand. He would he able to give the fullest description of tho systems m use at the places he visited, and also be able to utilizo the information obtained there from the most reliable persons and from observations made by himself. I think this information, and theso descriptions of what is being done m mining In America, would bo most beneficial when thoroughly known iv this colony and would help the mining industry of Now Zealand very much." Thero is much more equally valuable information contained m the paper from which we quote the foregoing, and we are glad to see that the Committeo m its report on tho subject ' recommends the Government to obtain from America and elsewhere, during the recess, full information as to th<x best and most effective methods of dealing with refactory ores" — a recommendation which we hope will be carried out, as thero is no subject which better deserves the attention of Ministers, no direction m which a small expenditure could bo undertaken with promise of so vastly beneficial results.