Show JUMBO EXTENSION A SURPRISE the recent report by president van dyck of the jumbo extension at goldfield nevada is disappointing the results shown do not agree with the optimistic forecasts made from time to time by the officials of the company the ore is much lower in grade and the mill has not been a success his report in full follows when taken over the company had a little more than cash in its treasury in order to develop the mine to its full extent it was apparent that a great deal more money would have to be raised unless the mine itself could be made to furnish a sufficient revenue to aid materially in its own development it was also clear that the available tonnage of ore of shipping grade was altogether too small to accomplish this result on the other hand there were considerable sid erable bodies of low grade material which if it could be handled in sufficient quantity and at a low enough cost would net a fair profit here again however the inadequacy of the cash balance evinced itself there was not money elou enough ih to build a mill and at the same time to develop the mine yet this low grade was of absolutely no value to the company unless it could be milled it was therefore decided to procure milling facilities at the least possible initial outlay other reasons besides the lack of funds commended this course in the first place the extent of the ore reserves was not known and they were e certainly not sufficient to warrant building a mill thorough development to determine their extent would mean much additional handling thus adding greatly to ton costs and moreover would not place us in much better position because the erratic distribution of values in goldfield ores renders it impossible to make accurate estimates of tonnage and value this is especially true of jumbo extension ores in the second place the ore contained gold silver and copper and no attempt had previously been made in the astri district et to mill ore of this character in the third place a number of tests were run upon the ore for the purpose of selecting an adequate milling process and these tests did not agree thus only by practical demonstration could it be determined what results might be expected from milling the only available milling plant which could be put in working order at a reasonable expense was the bonnie clare mill 38 miles south of goldfield and this plant was leased for one year the test from which the best results had been obtained indicated that estr extraction atio n could be made by co concentration and cy ahi leation and the mill was therefore remodeled modeled ie in accordance all therewith ere with As soon as the work of renio remodeling deling had proceeded eded far elou enough i gh to allawat allow it experimental runs were co conducted nau acted and it was found that could not be resorted to after concentration there still remained in the pulp such a percentage of copper as to render the cyanide consumption unwarrantably rant ably high and at the same time in order to reduce the copper content materially teri ally so much of the gold was recovered in the concentrates that there was not enough remaining in the pulp to pay for thus it was proved that although our ore could not be handled by the cyanide process it was much better adapted to concentration than we had supposed work was therefore discontinued upon the cyanide department of the mill and our entire effort was devoted to perfecting the concentrating department here it was a question solely of capacity and every effort has been made to force a large tonnage through the mill in maintaining the capacity we were forced of course to keep always in view the effect which increased capacity might have on extraction there is in our ore a certain class of concentrate which when the ore is crushed assumes a form which allows that force known as surface tension to apply very strongly this results in a float concentrate which is very rich and if the ore is crowded too rapidly over the concentrating tables much of its metallic content passes into the residue in the form of this float material therefore al thought there were added to the mill all the concentrators the building would accommodate the machines would not handle the product of more than 15 15 stamps the plant was run at this rate for a time and handled approximately four tori s per stamp per day the least change in the character of the ore however resulted in decreased extraction so that finally the attempt to run more than 10 stamps wab waa abandoned during the first quarter of this year every method of increasing the tonnage without decreasing the recovery was given a trial but by april it became apparent that we had attained the limit of the capacity of the plant the small tonnage rendered ton costs so high that the mill was but little more than paying its own expenses the following statement covering the mill operations erat ions for the first three months of this year will show you just what the results were tons milled freight net weight rental dry w weight eight 1 I 1 operating total expense cost per ton against this we have concentrates recovered of the value of marketing expenses and net cash received since capacity could not be increased thus reducing ton costs it was evident that some other means of effecting such a reduction must be devised our experience with tafe mill had proved that it ii was in f fact act two lo 10 stamp mills under one ofie roof that is 10 stamps can supply all the material which the concentrators can handle and the other 10 stamps can supply all the material the cyanide department can handle but neither concentrating nor cyaniding cyan iding department can alone handle the of 20 stamps the cyanide department was of absolutely no use to us since the development in the mine had failed to disclose any quantity of ore capable of treatment by the cyanide process the obvious course to pursue then was to secure some revenue from the cyanide department in another manner this was accomplished by means of an arrange arrangement mv nt made with the florence gold field mining company which in substance provides the following the florence company completes the remodeling and equipment of the cyanide department at its own expense and then operates upon its own ore employing 10 of the stamps the expense of maintaining and operating the plant is distributed between the two companies there Is an actual distribution of assaying repairs and replacements a distribution of unloading crushing stamping water tailings and superintendence per according to tons milled the florence company pays the entire expense of the operating the cyanide department in addition to this sharing of expense the florence company pays your company the sum of 1 upon each ton of ore milled by it until the sum of is paid this sum represents the expenditures already made by your company upon the cyanide department part ment of the mill the total result should be to cut the milling costs of your company practically in half the lease on the plant has been extended for a period of two years so that should the present arrangements admit of profitable operation there will be plenty of time at our command the remodeling will be completed during the current month at all events our milling experience has put us in possession of a great deal of information which is of great value to the company first it has demonstrated that our ore can be handled by concentration and a recovery of 70 per cent of the total metals can be made by improving the process which however can only be done in a new plant an extraction of 80 per cent can be made it has also furnished a basis from which the actual operating costs on any tonnage can be ascertained for instance we know that a plant installed at the mine with no freight or rental to pay could on a capacity of tons per month operate at a cost of riot not to exceed 1 per ton mine accounts for the first quarter of this year show the following tons of ore were mined at a total expense of 8 or a ton cost of during the same period feet of development work was done for your company by the gold field clerger mines company campany during this time lime it has for the purpose of this report been necessary to make an adjustment between mining and development the cost of development work has been arbitrarily placed at 7 per foot that being a reasonable figure the tonnage stated is the wet weight of the ore and also includes ore mined and sent to the mill but not yet milled at the close of the quarter the average value of the ore shipped to the mill has been 7 per ton no ore has been shipped to smelters shelters sm elters since there has not been a sufficient tonnage to warrant it there have been several occasions when large faces have been exposed from which average t assays essays of from to per ton have been obtained but in every instance they have failed to hold up under development thus far the richer ore bodies have proved to be merely kidneys or small irregular lenses and but a few tons have been obtained from them the ore supply upon which we must depend for the present seems to be the low grade material such as has been sent to the mill it is absolutely impossible to state how much ore there is in sight in the first place our development has not been done with a view to obtaining this information since the expense of so doing would easily double ton costs in the second place the jumbo extension mine is probably one of the most spotted in the district and it is well known that the irregularity in the occurrence and value of goldfield ores has rendered it impossible to estimate their extent all that can be stated is that there has been no difficulty in supplying lyng ore of the grade we have been milling the weak point in the policy which has been pursued is that it has not allowed a sufficient amount of development work to be carried on at all times the policy as heretofore stated was to attempt to make the mine pay for its own development and it cera tinly appeared that it could do so and net a profit besides every means of obtaining accurate information relative to the general grade of the ore and the process required for milling it was employed As nearly as the management could inform itself the average value of the ore was at least 20 per ton and over 90 per cent of value could be recovered I lad had this proven to be the case even a production of 1000 1006 tons per month would have represented a good profit the facts are however that the ore averages but 7 or 8 per ton and we have been able to recover but 70 per cent of that value to offset the disappointing condition every attempt has been made to increase the tonnage and reduce the expense both mining and development have been accomplished on one shifts shift per day with an underground force of twelve men the insufficiency of the amount of development carried carrl ed on is evident from the following there are disclosed in the polo verde workings three separate and distinct ore bodies one lying on the foot walf waif of the quartz mass one on the hanging wall and one near the center the foot wall body has been cut at one point only that is 1 in B raise from the second level assays essays of from to per ton were obtained across ten feet of ore the hanging wall body has been cut at several points but only two have been opened on it there were the E and C both of which produced a better average grade of ore than did the main ore body development has been confined almost entirely to the main or central shoot the result is that we have one ore body not explored at all another with but a meager amount of work done on it and a third which warrants a great deal more development furthermore none of the more remote portions of the mine have been beeh touched toward the south end of the claim a raise driven some time ago exposed an immense vein from which assays essays as high as 40 per ton were obtained our drift on the fourth level is headed far enough to penetrate it this vein is probably the same one which occurs on the 1000 foot level of the clermont in the bulldog fraction tying along the north end line of the loverde paloverde Po the goldfield consolidated encountered large bodies of ore some of it very high grade there is every reason to believe believe that alie downward extension of this ore will be found in our ground but none of our workings have been extended far enough to prove the f fact thus with three known and two probable ore bodies only one has been to any extent developed still another inconvenience resulting from the lack of development work is that there never have been a sufficient number of places located from which ore might be delivered it is true of all mines and very J particularly of the jumbo extension that l a may deliver excellent ore one e day and waste the next 3 throughout all ore bodies there are more or less barren zones and if it so happens that several encounter a lean area j at the same time the consequences are alej serious unless there are plenty of other places to draw from this has occurred j several times in your property although there are a number of places where ore can undoubtedly be obtained if a little more development work were carried on there have been times when the mine appeared to be a veritable bonanza and other times when it appeared quite the reverse if more mor are opened up it is likely that a very much better grade of ore can be maintained on the ot other lier hand the policy which was waa adopted has proved to be better than any other which could be applied to this P pa nicular mine fifteen months ago ther therb were just two courses open to us one w wa to devote our entire attention to development and the other to do as we have done had we pursued the first mentioned course cur funds would have lasted just about nine months and it is impossible to state whether we would have been better or worse vorse off than we are now we know what our ore is both in character and value and also how it can be treated had we merely developed we would have known nothing about this nor would we have had any ally data on either mining or milling costs we are now in position to state positively the cost at which we can operate in any department these facts are of prime importance to the jumbo extension on account of the base character of its ore and its low value the foregoing furnishes you with full knowledge of the present condition of your company it explains the policy which was adopted and the reasons for adopt adopting hug it it is not intended as an excuse for the policy or the results there is no use hoping for what might have been for ten to one what might have been is worse than what is the mine is what it is and the matter resolves itself pretty largely into a question of how to make a profit out of 8 ore cont containing dining the proportion of gold silver and copper that ours does it can be done and the present management if retained will use its best endeavors to accomplish com that result there will be no change in the policy heretofore pursued except that a greater amount of development work will be carried on |