THE WAIHI MINE.

New Zealand Herald, Volume XXXIV, Issue 10514, 6 August 1897, Page 5

THE WAIHI MINE.

IMPORTANT development WORK. £90,000 TO BE EXPENDED, DESCRIPTION OP THE WORKS IN } PROGRESS. _ [BY OCR SPECIAL REPORTER.] The important works undertaken by the above company eclipse all other development work in progress elsewhere in the Peninsula, and afford unmistakable evidence to those inspecting the works, that though an enormous amount of gold is being yearly taken out of this valuable property, the company are not pursuing a selfish policy, but are intent on pushing on development work, erecting the latest improved machinery and appliances for treating the ore, and increasing the crashing capacity by more than doable. Dismissed in such a few words, the important nature of the work does not at first strike the casual reader, and a visit of inspection is really necessary to obtain anything like a fair idea of what has been done, the difficulties that have been and are being overcome, and the important works which have yet to be undertaken before practical effect is given to the policy decided upon by the directors. At Waihi splendid work is being carried on in the mine uuder the able superintendence of Mr. Gilmour, the mine manager. Since the new developments occurred in the mine, when the quartz in the famous Martha lode changed in quality, becoming much richer in places, the reef has maintained its substantial proportions, being in places fully 20 feet wide ; taking the stone all round, it has shown a decided improvement in value, in proof of which the increased monthly returns may bo cited as sufficient proof. At the No. 2, or Martha shaft, excellent progress is being made with the erection of the pumping and winding machinery, which is rapidly approaching completion. At present 00 stamps are at work at the company's battery, but at Waikino tho erection of the new crushing plant is well under way, and'very shortly 190 stamps will be at work. It is the intention of the company to erect 200 head of stumps at Waikino, and though nothing definite has, it is understood, been as yet decided upon as to the commencement of the erection of the third set (to make up the 290), there is a probability of this work being undertaken shortly after the 100 head now being erected are working satisfactorily. At the Waihi Company's battery site at Waikino quite an army of men are employed, and the work of erecting tho 100 head of stampers is proceeding with all expedition. Fifty head are already in position, the foundation work for the vats in the tank-shed is being gone on with, a commencement mado with the excavation for tho kilns, while further up the line of rails running from Waihi to Waikino, and on which the company's locomotive the Ohinemuri is now running, the work of erecting tho huge dam across the Ohinemuri is being pushed on with all possible speed. Altogether about 500 men are at present employed; and as each of tho officials in authority have proved themselves to be conscientious and capable men, everything is progressing rapidly, smoothly, and in a mannor satisfactory to employer and employees alike. Mr. William Barry is general superintendent, and during the last year ho has had a difficult task to undertake, a task which present indications show will be completed in that businesslike and thorough mannor which has characterised the carrying out of all works of importance which the company has undertaken. And in this connection it would be unfair to fail to recogniso the valuable assistance rendered by Messrs. Stafford (sub-superintendent), Roche (the superintendent of works), and C; Eraser (who prepared the plans of the new battery, etc., and is superintending the erection).

DETAILS or THE WORKINGS. ] Entering the cago doacent is made to the No. 5 level, and as soon as tho first chamber iB entered tho Welcome lode may be seen, i the reef running in almost a north-westerly direction. Tho lode in this portion of the level is about 30 feet wide, and is composed of quartz yand mullock, Continuing along the drive the point whore the two reels are closest) togethor is arrived .it. Forty feet from tho Welcome lode; and running almost parallel, the Martha reef' was intersected, but-, as stated, that was the point at which tho two reefs were closest together. Ftom this to the next level there is a block of 70 feet of ore intact. While at/ the No. 1 level the Welcome is perpendicular, at the No. 2 level both reefs navo a decided dip, the Welcome underlying west and die Martha to the oast). The assumption is that these lodes meet at a greater depth than has yet been sunk, and as they are underlying in different directions the question is which body of stone will prove tno strongest, and whether the lodes will carry on as one with the same underlie as the strongest lode at present has? The general opinion of thoso who hare viewed the Woloome and Martha lodes, is that the latter is by far the strongest body, and that ab the junction of the two reefs at a depth the present underlie of the Martha, which is east, will be continued, while others are of opinion that the effect of two such large bodies of quartz meeting will be that the main body will become vertical. This, however, is a matter which only time and development work will determine. Throughout) the level the lodes vary considerably in width, for while at one point they pinch to about a footwido, they widen out again to a good deal more than thoir averago width. Take the Martha lode for instance, which «m named by the original discoverer, Mr. W. Nicholl. Ab one point the Martha widens out to about 50 feet. This is particularly noticeable ab what is termed ''the blow," where tho reef made rapidly to the width stated, and then gradually resumed its usual width—viz., 15 to 20 feet. Continuing along the drive, the point where the recent important developments occurred is arrived at. These have already been described at length in the columns of the Herald, eo ib !b unnecessary to .recapitulate them in this article. Shortly, ib was thought, on account of the Martha lode pinching out in the ad lb and No. 1 levels,' that the reef did not lio beyond a oertain point, and, indeed, many held the opinion that the run of gold on the north-eastern portion was coming to an end altogether. In the No. 2 level the reef began to taper off, and ib was but natural to assume, as & similar' occurrence had taken place in the top levels, that the reef was " petering out" in No. 2. .The mine manager (Mr. Gilmbur) determined bo ascertain whether the lode did exist beyond the point stated continued .driving and croascutting, and after crosscutting through a horse of mullock, again picked up the which had evidently been thrown in a northeasterly direction. The first crosscut was put in in a south-easterly direction, but no reof was met with at 20 feet, pug continuing all the way— theory is that the Welcome reef has touched the wall of the Martha before ib reaches this point. But in tho north-western crosscut the reef was again picked up, and proved to be even richer than bafore. The reef at present in the face looks very promising, and is said to be yielding some of the richest stone which has yet been taken oub of the mine. > Unfortunately, however, the ore from wall to wall cannot be treated on account of . the refractory nature of a portion of tbe stone mined. Nothing of the kind has occurred before, so that the change is all the more remarkable. . The stone is heavily mineralised, containing large quantities of blue sulphides. Toe ore is supposed to be very rich, but too refractory to be treated in the same manner as the other quartz, and is being paddocked until a method of treatment is decided upon. Some very interesting experiments have been carried oub by Mr. Banks, the company's metallurgist, with the object of ascertaining how. this ore can be > treated, and there is a possibility of the problem being .solved. Those who . have had a good deal of experience in the treatment of refractory ores, state chat the , ore can be treated by cyanide after being roasted more .than at)., present, ( but it is understood ' ( that. the treatment now in operation at the Waihi battery resulted in a saving of only7o per cent., and what was considered a faintest was made, some. 20 i tons ; of ore being , treated. ; Sinoo' then, however, experiments ; made - have < (Men attended with ,a fair, measure 1 of ; ; sucoeas, and, as stated, there te » \ probability of the difficulty ■ being overcome; in the near i future. The refractory or# , fortunately ; forms but a small portion of the reef, so that beyond the saving of \ the. quart* mined, MM pttiwM •< tue wlphMw Maw ' .y-; ; -w

practically no inconvenience. The several crosscuts pub through to test the wealth of the lbde proved it to be a splendid body of stone, averaging at this point about 14 feet wide, and the reef on the iace at the time of our representative's visit was 15 feet from wall to wall. At the other levels the drives are being extended on the Martha lode, and winzes have been sank to connect with No. 2 level. In the other levels the Welcome reef is being driven on, and the width varies a good deal, but averages about 14 feet. Stopinjr is now in progress in No, 2 level, it being 21 feet from the top of the stope to the floor of the level. The stope is 23 feet wide, going west it widens to 70 feet, and its length is 150 feet. Other works of a similar nature are In progress and an. immense body of ore ia'at present available. ' It is estimated that when the additional 100 head of stamps mo working something like 7000 tons of ore per month of four weeks, or over 90,000 tans per year will be pnt through, and it is also estimatetLthat there is at present sufficient ore in flight to keep .200 head of stampers going for several years. In the No. 2 level the Martha lode has been opened up about 1040 feet, 640 feet west and 400 feet east. In No. 1 level, which is 80 feet higher, the reef has been opened up about 1100 feet wort of the crosscut and 200 feet east, and all has been stoped up from this level, In the adit level,' 80 feet higher, the reef has not been so much opened up, as at 1000 feet they came near to the old surface. _ In the Smithy levol the reef has been driven on about 1000 feet east and west and here the Martha has bean worked right out-. In the intermediate level on the Martha 500 feet is the total length opened up. The Welcome lode in the No. 2 level has been opened up 1000 feet, in No. 1 1500, and in the adit level 1600 feet.

THE WAIHI AND VICTORIA BATTERIES. The company's battery at aihi is close to the Waihi- Onion.shaft, and about half-a-mile from the No. 1 shaft. The ore is convoyed in trucks to the kilns, 12 in number, which contain in addition to the wood, 150 tons of ore. Most of them are bricked. The number of stamps is 90, each stamp weighing 8501b. The number of cyanide vats at present in use is 24, but an additional eight are being placed in position. The ore, after being dried, is lifted by means of an hydraulic lifb to the stone-breaker, and from there conveyed to the stampers. A Krom mill will be used in conjunction with the stamps, and this, it is thought, will allow of a substantial increase being inado to the quantity of ore at present treated. The battery is at present driven by sir Pelton wheels, bat, in addition, auxiliary steam power is also available. In the engineroom is a .350 horse-power engine. This engine is capable of driving the whole mill should it be required. There is also a 120 horse-power American engine, and a 20 horse-power Tangve. In the boiler-room are two of Babcock and Wilcock'a boilers, a large multitubular boiler, and a semiportable boiler. The high pressure waterrace has a fall of 148 feet, and the low pressure race a fall of 55 feet. The

hydraulio lift is oapablo of lifting 9001b in each track. The new vats that are being erected will hold about 30 tons each. The mill is kept comparatively clear of dust by means of an fcxhadsb fan, which does its

work well. Regarding the treatment) of the ore, it was at first thought that wet might 1 be better than dry crushing, and experi- i merits hare been conducted with the view . of ascertaining whether such would prove ! to be the case. The results of the experi- i moots were that the extraction by web was ' not so good as that obtained by the dry process, while the cost of the cyanide was a good deal more. The solution i was varied, commencing at "4, and < working up to '6, but with results that were not considered satisfactory, and it was i consequently decided to adhere to the dry i crushing, and the new plant at) Waikino will therefore be a dry crushing one. The opinion of those conducting the experiments was to the effect that though the ore from another mine— Crown, for instance —could be treated successfully web, it did not follow that it would be advantageous to adopt wet crushing for all classes of ore. The ore 9 from the mines in the Katangahake, Waitekauri, and Waihi, and in fact in all other districts, varied to such an extent that while it was quite possible the quartz from one could be treated wet and better results obtained, ore from another, and possibly an adjoining property, would be of such a nature as to render it impossible for it to bo treated successfully by any other than dry crushing. This, it is important to note, bears out in every detail the opinions expressed by the other experts with whom our representative conversed, and whose opinions had been formed only after giving the matter'long and earnest consideration; It will thai be leen that the consensus of opinion ot those well qualified to speak on the subjeob is that wet is admitted to be preferable to dry crushing, provided (and herein lies the whole crux of the question) the quality of the ore will admit) of it being so treated. Another matter which has an important bearing on the subject, is that in some instances it has been found that the wear and tear of the machinery used for web is much greater than that caused by dry crushing. When the Waihi Company conducted their experiments, they made complete arrangements so that wet crushing would be given a fair trial. When 114 tons had been crushed wet it was ascertained that the breakers and dies were almost worn out, whereas with the dry crushing, changes of these parts would be required at much longer intervals. The wear and tear of the machinery was nob compensated for by the better extraction, and in addition it was ascertained that wet crushing caused a large amount of slimes to go through tbe blankets and plates, and caused a great deal of trouble. ■ Bobthie by the way. Coming back to the : works .in progress, the next place visited was Waikino (formerly oiled Owha: roa),.where the 100-sfeamper battery is being erected. • A locomotive line has been laid from Waihi to Waikino,'» distance of about six miles, and the i engine now runs from close to the No. i shaft to opposite the offices at the battery, which has been called the Victoria . in commemoration of the Queen's Record Reign. The buildings are imposing looking structures, and when in operation Waikino will become a small township itself. The motive power used will bo obtained from two water-races —high pressure and low pressure. The high pressure racd, which is conveyed over six miles from below the Waitekauri battery, will drive the two Pelton wheels, which are each of 143-horse power. The high pressure has a fall of 198 feet, and contains 15 sluice heads. The low pressure race is brought from the Ohiriemuri river, over which a stone and concrete dam is being erected. The dam is 110 feet in length, 13 feet 6 inches wide at tho base', and is a substantial look* ing structure, capable of resisting any pressure when freshes occur. The race is eight feet at the bottom, four feet deep, and twelve feet wide at the top, and will con* tain 60 sluice heads, having a fall of 55 feet The low pressure race will drive two tun lines, which will give about2oo horse power each, and the supply is divided in the battery by means of branch pipes, one lead" ing to each turbine. The branch pipes are 4 feet 6 inches in diameter, diminish* ing to 3 feeb 6 inches, while another smaller branch will be connected to drive the electric lighting plant. The branch pipes are fitted with equilibrium valves, said to be the first of the kind made in the colony. The pipes were made by Price Bros., of the Thames. Following in imagination the passage of the ore from the'time ib is conveyed in the trucks (which are steel waggons, side tipping, holding ! li tons each) to Waikino until it enters the cyanide vats, we come first to the kilns which will be six in number. The ore will be conveyed to the kilns, which art about 30 feet deep by 26 feet, and capable of holding about 500 tons, from the main tramway by means of an incline cable tram which will be worked automatically by a winding engine. The grade . of the incline tram is about l.in 10, /and when laid will be about 14 chains long. There are two kiln ' drives into which the kilns will be discharged, and running along the kiln drives will be; a cable tramway conveying the trudks from the kilns to the arebreaker?.' The.trucks.can be switched on and off at any,point by means of automatic clips, remain .mb the different kilns until filled, switched on again, conveyed to the i breaker and back "(again, to any desired : point 1 for 'filling. 'There will be <• three * breakers; First) 1 * No. 5 > Gates's crusher,' ■ the stone passing through a revolving screen. ' That wbt& passes'through the screen will I go into separate hopper,' while th*.(Mg}l i !wf will W-law > GMfftl

crusher until farther reduced. Along-; side the No. 3 cruiher will be erected': a Blake • Marsden, which , will act as 3D auxiliary. All this _ plant, breakers and cable tram, will be driven by a separate engine, from the hoppers theore will be conveyed in tracks worked by means, of another cable tramway to the ore-bins of •the battery, where ' they are discharged. This will be effected by means of a pin, which, placed at whatever bin the ore is required, causes the trucks, which are wrought iron with bottom dischargers, to open, discharge, and continuing along the tram, right themselves automatically, and continue on their way to the ore-breaker, where they are again filled. This ingenious arrangement will effect a great saving of labour and handling, and the ore will require no handling from the time it leaves themino until ib enters the cyanidevats. The arrangement mentioned was designed by Messrs. Barry and Fraser, and will be the first in use in the colony. The 100 head of stampers, 50 of which were erected at the time of our representative's visit, weigh 10001b each, and have _ double discharge mortars, and it is estimated that that they will put through an average of aboit 1J tons of ore per day. From the third floor a complete control of the machinery is secured, and on this floor the electric lighting plant, workshop, etc., will, be located. The tailings are conveyed outside, and a concrete culvert for sluicing put) to the river will run under the building. The cement mixerwill bsdriven by a traction engine. As. a very large quantity will be required, ib was deemed necessary to expedite the preparation of the material as much >3 possible. The building for the reception of the precipitation plant will be erected alongside the vab shed, and will be 82 feot by 05 feet. There will be two concrete sumps, with 10 towers 18 feet long. Theasaaying-room, laboratory, andimelting* house will be erected next to the vat-shed, and close to that is the engine-shed. Nothing definite has as yet been decided on as to the auxiliary engines for the mill. The specifications forwarded Home, are for two sets of triple expansion vertical engines, connecting direct to the shaft for use only when the water-power is not available. The boilers are to work up to 1651b

From the above description a fair idea will be obtained of the important nature of the work undertaken, and it is to be hoped that the company will be well recouped lor their very substantial outlay. • As stated before, the policy of the directors has been what may be termed a " progressive " one, and those who have the good of the colony and the advancement of the Auckland district at heart, will be gratified if tile Waihl Company are, by increased returns, well recompensed for their expenditure.