Show A an n ideal steam stamp for prospectors BY MARK L LAMB probably there are in all mining countries and certainly in the majority of them hundreds of promising claims in the hands of parties who are not able to expend the thousands of dollars necessary to develop their properties into paying and salable mines and who do not feel justified in undertaking der taking the erection of a five or ten stamp mill knowing as they do that the first cost of such machinery is only a fair start toward the installation of the mill and placing thoroughly good crushing amalgamating or concentrating plant of moderate capacity in the shortest possible time with the least material and for the least money the machine has not only proven itself highly successful for this purpose but has shown an economy in all matters pertaining to its operation which compares very favorably with results obtained in works of larger capac city showing that the original plant can be readily augmented from time P e tremain steam stamp mill in the field it in readiness to run it being a fact that the cost of erection is often m more ore than twice the cost of machinery in the event of disappointment in meeting expectations in development such a plant would be largely a fixture and would probably stand as an evidence of faila failure re because the money spent in its erection would necessarily be lost in moving the machinery to 0 ther other mines where possibly the same experience might be repeated the tremain steam stamp mill has bee been e n designed to meet the demands of those who own mining properties in the first stages of develop development nent enabling them to establish a p 1 4 ait R J tr 1 tremain steam stamp mill operating in rhodesia to time as the development of the mines progresses by the addition of more machines at a cost of little more than that of the machines themselves the machine is entirely self contained and may be described as consisting of two stamp stems the upper ends of which terminate in pistons working in cast iron cylinders after the manner of the steam engine these pistons are turned out of the solid forging which forms the stamp stems and are fitted with two sets of piston rings malting making them steam tight the piston rods which pass through the stuffing boxes are slightly smaller in eter therefore the steam pressure which is admitted under the piston to raise the stamp is confined to an area which is the difference between the diameter of the piston and the piston rod amounting to an annual ring about three quarters of an inch wide this area is small but sufficient to quickly raise the stamps the total weight of which is but three hundred pounds father either piston in its travel toward the top of its cylinder passes a small steam port which admits the pressure to the valve ff mechanism and moves the valve to its opposite position the movement of the valve cuts off the admission of steam to the underside of the I 1 piston and admits to the underside of its mate at the same time connecting the top and the bottom ends of the first mentioned cylinder thus allowing the confined steam which is holding the stam up to be conducted around the piston to its upper side and acting expansively upon the large area encountered to so energetically get getic feally ally assist the pound stamp in its I 1 movement as to strike a blow u upon pon the die equal to that of an to 1000 pound gravity stamp the pistons alternate with ditl each other perfectly and when the valve is moved back to again admit steam to the underside of the first mentioned piston it also connects the top side with the exhaust port so that the steam remaining after the blow has been struck is passed into the atmosphere this arrangement makes it possible to use the steam expansively and to obtain the same crushing effect with each drop of a pounds stamp as would be obtained with a gravity stamp of to pounds dropping eight inches depending upon the pressure used instead of being limited to about ninety drops per minute as with the gravity stamp we are able to obtain a speed of or more drops per minute of each stamp and it will be obvious that the crushing capacity must be correspondingly increased the speed of the machine is variable at will that being a matter depending entirely upon the pressure used approximately it is as follows with sixty pounds pressure drops with 80 pounds drops with loo pounds drops per minute of each st stamp amp etc increasing the pressure increases the speed and vice versa it is customary to carry about pounds ot of pressure at the boiler and maintain a speed of about drops per minute it is desirable that the tremain mill be situated as closely as convenient to the boiler carrying steam a long distance effects a loss of pressure and entrains water which materially affects affect the operation of the machine reducing I 1 speed and effectiveness to get the best results pounds pressure of dry steam must be maint maintained affied at the mill the capacity of the mill will vary with the character of the ore and size mesh of the screens in use from eight tons under the he most adverse circumstances to twenty to tons ns when stamping friable ore in southern rhodesia says a writer in the mining scientific press mr cyril E parsons from whose article the following has been abstracted more than forty small tremain steam stamp mills are in constant operation occupying quite an important position in the gold mining industry As soon as the royalty system of payment was introduced into this territory numerous small producers appeared as if by magic and the industry received a tl great impetus the majority of the deposits it must be remembered are small the owners could not face a large capital outlay in many cases small deposits containing only a few hundred tons of moderately high grade ore had to be dealt with and consequently a demand arose for a small machine which did not cost much high railway and transportation rates emphasized the necessity for some portable milla barrel of cement for instance which ich at the port of beira costs delivered to the prop property efty costs 1500 1506 in other words third class goods which chic h in elude clude the majority of ordinary mine stores cost per ton for railway freight alone the tremain stamp mills milis weigh pounds each consists of two stamps the upper ends of the stems being two pistons moving in cylinders and actuated by steam to the lower ends of these stems shoes are attached each stem and shoe when new weighing pounds the machine is worked by steam direct at a pressure of about pounds and the stamps work in a mortar with front and side discharges at salisbury the capital the whole outfit comprising a mill amalgamating table and a ten horsepower boiler can be had for 2600 and with another 1000 erection and extra expenses can be provided the excessive freight and haulage charges amount to about twice the original cost of the mill ed the entire plant would weigh about eight tons the foundations are usually inexpensive the makers recommend a pile twelve feet long and thirty inches across but shorter lengths of nine feet answers well depending a good deal upon the na nature ture of the ground in one instance nine foot pile was cut out of the trunk of a tree severed above the fork thus two legs appeared at one end this end was placed downward in the prepared excavation with the idea that the splay increased the rigidity of the pile on the prepared and level face of the pile block rests the mortar w with it 11 an intervening piece of blanket rubber in iii bertion ser tion or even buck hide the boiler is set on rough foundations as near the mill as possible to avoid loss of steam through I 1 c condensation and to ensure a constant sup ri lly y of dry ary steam A small automatic rocker feeder is usually provided A rock breaker is a distinct advantage but necessitates a small engine which in districts where native labor is cheap and plentiful plent ful can be dispensed with As a substitute biggers nig gers are employed to 11 spall or break the rock to the required size which is that of a walnut by hand labor the mill often has bas a dilapidated appearance with a few sheets of old battered secondhand second hand corrugated cor ru iron to house it supported on crooked native wood poles for straight timber in that country is unknown scantily attired natives may be seen moving leisurely about while the white man may be underground at the mill or in his hut close by snatching a few hours rest accurate accounts are seldom kept and consequently it is most difficult to compile reliable data the life is undoubtedly hard especially in the rainy season and during the hot and more u unhealthy nhe althy months which are Al april iril may and june the men in these outside camps living away from decent conditions and comforts frequently suffer from malaria camp fever or blackwater black water and these severities are accentuated I 1 when the venture is a bad one find and money is being lost all sorts and conditions of people cleare are g these plants and the individuality tia bality lity or character of the individual is quickly evident from the manners and ss system that surround his small undertaking the cases described in this article are actually a collection of notes taken at different periods on the spot and they represent as closely as possible the results obtained while they were written first case one tremain trema in mill was operating crushing tons per day being a duty of tons per stamp with this plant the consumption oil was 20 gallons costing 8 cents per ton of ore crushed this however included oil used on a hauling engine and small steam pump as well as on the mill the fuel was wood and cost per cord and it took 85 cords to crush tons or 75 cents per ton shoes and dies came to per month being four shoes and two dies at and respectively the ore was a fairly hard oxidized second case the mill was perched on the side of a steep hill and the boiler an ancient specimen showed a pressure of pounds steam lecause because besides supplying the mill it was working a pump at a level feet below the mill and was throwing water from a stream to the mill the fuel consumption was 2 cords per day costing 3 per cord the shoes lasted three weeks and the dies four weeks crushing hard quartz through a 20 mesh screen in this instance the owners seemed uncertain what ton tonnage nage was being treated in fact they were very uncertain about the consumption of most of their stores third case the mill was in the penha longa valley near township fuel was very scarce and co cost st per month at 6 per cord the ow owners hers considered that the mill dealt with twelve tons per day through 20 mesh but they had never taken any careful measurements the ore was oxidized quartz and schist st fourth case fuller data i were obtainable th the e mine and mill were on sloping ground close to each other in thick bush veldt ten miles from the railway and 1200 I 1 yards from a large riv river er which furnished the fhe water two white men and about seventy natives were at work at the outset a niec mechanic cianic was engaged to erect start and work the mill but in about three weeks the owner learned to handle it himself the original outlay may be summarized as follows tremain nain mill mine pumping and piping 2 7 64 5 boiler 6 horsepower for river pump 1220 yard pipeline pipe line four tanks for mill and boiler feed w auter ater one donkey pump old iron corrugated for housing pipes fittings tools 1 freights forwarding warding total vone boiler was on the property to start with and excepting the mill the above was all secondhand second hand material mining milling and general expenses for five months are given as follows mining and milling white wages native wages stores general white wages native wages age of the total costs in rhodesia f ully fully 40 per cent of the total expenditure goes to stores owing to the high f freight rates the average cost for five months of native labor came to per head while the food consumption worked out at 27 pound of meal per head per day each individual does not consume more than 21 pound the mill was worked by one ten horsepower boiler at pound steam pressure making blows per minute the cutting price of fuel per cord for four N k 97 tr IMF V ole 5 fo 1 ra 71 na aw ua 4 sn installation of eight tremain mills showing battery resulting from gradual additions made to the single original prospectors mill stocks and stores 2 13 mess account per man traveling expenses 1 I miscellaneous prospecting bank charges 1298 total the figures given make no allowance for owners time and a few other smaller charges appear to be omitted it will be seen that stores occupy a high perce fit feet length is 1 and for 2 feet pieces it t is the consumption amounted to three cords per day but this includes wood burned at the pumping station previously mentioned the ore was schist and quartz mixed and the mill crushed ten tons per day through 26 mesh screens which were bursting daily at first due to over feeding and 4 from the same cause the guide blocks wore badly and had to be replaced the the silvered copper plate provided with the mill measured 9 by 4 feet and was set with a drop of 1 inch per foot it was scraped daily and dressed every six hours the oil consumed was ten gallons per week costing 41 per month the sight feed lubricator attached to the steam pipe is one of the most important factors with the mill it must be carefully attended to and adjusted for in many cases it can be seen going wrong owing to the vibration and as soon as the steam stamps are insufficiently lubricated they practically cease to work at this mill from tw two 0 to three drops per minutes was wa s the allowance the amalgam yielded per cent bullion having a fineness of with this mill as well as others in the country feeding mercury into the mortar box is practised practiced but the advantages are not apparent the loss or consumption of mercury from the crushing of tons yielding ounces fine gold was 9 cents per der ton the tailing assayed 8 cents selecting one month the output S tf was ft as worth 2200 we find the following payments had to be faced and these may be regarded ragar ded as a fair example royalty to claim owners government royalty 21 2 0 o of the gold bank charges claim charges 2425 total the bank charges analyzed further as follows melting the gold 1625 commission and transfer refining 7 1055 Ss assay ay fee total from these figures it will be seen that the government fee reached made up from claim licenses and royalty the best run of mills was days in a month of thirty one days but in this case loss of time was in a great measure attributable to having only two white men the joint between the mill cylinder casting and the valve chamber should always be well made in the present case brown paper and thin canvas were both tried but are ara stated to have been unsatisfactory eventually woven asbestos and graphite also cardboard and boiled linseed oil were used and answered well the former lasting one month the foundation block was buried only 7 feet deep and the automatic feeder was dismantled since it did not suit theore the ore between the boiler and mill 26 feet of uncovered steam piping could be se seen en the na natives tives engaged were distributed as below I 1 I 1 natives breaking and shifting rock 7 removing tailing from pits 3 I 1 stoking b boiler 1 carrying wood to boiler 1 total 12 about to 1000 gallons of water were being pumped from the river and used cacti hour fifth case thirty miles beyond the last mine was another tremain mill at work under different conditions the mine workings are on the top of a rugged hill covered with vegetation and around it deep valleys have flave been eroded the mill was on the bank of a large river feet below and water for milling was raised by a small feed ed pump a distance of feet |