History and Exploration
During 1948, Karl Gunterman. a prospector who was associated with Aime Breton of Sault Ste. Marie, ONT,CAN, had ran a Geiger counter over rock and mineral samples. It was a piece of pyritic conglomerate labelled Long was sufficiently radioactive to arouse Gunterman's curiosity. At this time, Gunerman and Brenton had traced this sample to the east end of Lauzon Lake in Long Township where a series of test pits were found in a bed of pyritic conglomerate, in which these test pits had been presumably dug by a prospector looing for gold or copper. The ground at this time was staked by these two prospectors and efforts were made to interest geologists and even mining companies in the claims. Although approachable radioactivity was recorded at the surface, assays samples apparently contained little uranium, although some thorium was present in the samples. Among one of the geologists who had gotten interest in the property was Franc R. Joubin. Mr. Joubin had believed that the belt of Huronian rocks between Sault Ste. Marie, Sudbury, and Cobalt had already known for copper, nickel, cobalt, and silver that should also contain uranium of hydrothermal origin.
Within 1949, it was during the re-routing of Highway 17 just east of Algoma Village, when a German immigrant employed on the construction job discovered radioactive material at the old mining location. A total of six samples of material taken from this section assay between 0.025% to 0.15% U3O8 per ton. Before this exact location was discovered, from which samples had been taken, could be ascertained, as the German was drowned. Some of the most available information on this area was publish by Lang in 1952, in the first edition of Canadian Deposits of Uranium and Thorium. This further discovery of uranium In Lang Township would rekindled Joubin's interest once again in the Breton Property. The claims at this time had rather lapsed and it was once again opened ground that became shortly after secured. Most of this staking was done with backing of J. H. Hirshhorn, when a block consisting of 36 claims was staked and held in the name of Peach Uranium Syndicate, that was renamed into Peach Uranium and Metal Mines, Ltd. Joubin again would find himself confronted with the problem of high radioactivity on the surface but little uranium was reported from assaying. Assays had also revealed insufficient thorium to cause the observed radioactivity.
Joubin at this time had additionally noted the similarity of the Long conglomerate to the famous gold-uranium bearing-quartz-pebble conglomerate of the Rand in South Africa, and in March, 1953, he visited the United Kingdom to obtain background information on these rocks and the process of extraction (acid leaching). Joubin had than theorized again that the weathering of the Long Conglomerate could potentially lead to the formation of sulphuric acid which in turn could dissolve the uranium from the surface showing of the uraniferous conglomerate. By this time, Hrishhorn would additionally provide the capital for diamond drilling which was begun on April, 1953. It was stated that the first three holes had indicated substantial tonnage grading 0.13% U308 over a mineable width. This resulted in the commercial possibilities of the deposit that were now apparent.
By June, 1953, Peach Uranium and Metal Mining Limited had formed a subsidiary company called Pronto Uranium Mines, Ltd. Most of this at the time was mainly being aimed at bring the property to production and developing it. Another extensive diamond drilling program would be initiated using 300-foot centers and within a years times, the discovery of the Pronto Block had estimated to contain block out to merit a $55 million contract with the Eldorado Mining and Refining Limited. The ore zone at this time was additionally traced and outlined for 3,500 feet along strike, with an average thickness of 7 1/2 feet, and it was traced to a depth of 1,000 feet. At that depth it was considered to have been terminated against the Pronto Thrust Fault. The ore Zone had also been bounded on the north by surface outcrop, to the east and west by facies change, and to the south by the Pronto Thrust Fault. Exploration work at this time had additionally failed to reveal either other ore zones along strike, or the faulted continuation of the ore-body.
The Pronto Uranium Mine was first place underdevelopment in 1954, when a staking was made by the newly incorporated Pronto Uranium Mines, Limited. At the time it was rather reported that the company had staked a total of 139 claims, in the townships of Long, and Spragge, within the District of Algoma. Mining operations on the historical Pronto Mine had all started on May, 1954, and continued till the end of that year. By this time a vertical three compartment shaft known as the No. 1 shaft had been officially sunk to a depth of 591 feet below surface levels. With shaft sinking taking place this would also establish levels 110, 207, 283, 372, and 464 feet from the surface. As the mine continued to expand it was also reported that diamond drilling had consisted of 126 holes totalling 37,749 feet from the surface, and 7 holes totalling 456 feet from underground.
Significant structures had also started to be developed and included 10 staff residence, carpenter shop, pump house, powder magazine, machine shop, concentrator building, service building, and a 250,000 gallon steel water tank. Company officials from the Pronto Uranium Mines, Limited had also installed a 250 Kilovolt ampere, a 550 volt, 3 phase, 60 cycle General Electric Generator, Some more equipment was also purchase, and included a two stage, 2,000 cubic foot per a minute Bellis, and Morcom Air Compressor driven by a 400 H.P electric motor, and a 1,000 cubic foot per a minute XVHE-2 Canadian Ingersoll Rand Air Compressor driven by a 200 H.P electric motor. Almost all the work within this time was being done under contract as the company only employed 4 miners. Nothing else had occurred within this time period of preparing this site for further production.
It wasn't till 1955, when a considerable amount of work had occurred within this time period, and was focus on expanding the newly developed levels. The information below provides the details on the new expanded levels, and their development within this time period.
Other building within the time period had also became developed, and included an Assay Office, a 102 by 112 foot service building, a hoist house, and crusher house. The Pronto Uranium Mine, Limited had also installed the two Canadian Ingersoll Rand, and one Bellis and Morcom Compressors, and a 54 by 100 inch double drum Canadian Ingersoll Rand Hoist. In addition this had also started up milling operations on August, 24, and continued to operate for the rest of the year, in which it treated 75,289 tonnes at a daily rate of 550 tonnes. A significant amount of miners also became employed, and ended up totalling a workforce of 224 employees.
All development within 1956, was being confined to all 5 producing levels, and an 26 degree adit was driven to a depth of 50 feet. Most of the work within 1956, had reached the ore-body limits of the first. and second level drifts. Some more work had also completed 40% of the ore limits on the third level of the Pronto Uranium Mine that year. Further expanding during that time period was also taking place on the four level, and had commenced in December, 1956. The development rate was also increased by the end of 1956, and had been continued to preparing levels for higher then normal production. Almost all this work was opening the eastern portion of that had a flatter dip in the ore-body, and by faulting. Generally this whole entire eastern ore-body was being extensively developed by Drifting, and Crosscutting.
Almost all production that year had comprised of 396,260 tonnes of broken ore in the stopes, 8,404 tonnes of broken ore in stope preparation, and 1,631 tonnes of broken ore from development work. In addition it was reported that the average value of this ore had assayed 2.35 pounds of uranium per a tonne. The whole entire width of the ore-body had been mined from 8.1 feet, and the average stoping width was 9.0 feet. More so it was reported that the stope sections had also resulted in a dilution factor of 11 percent, which was base on ore zone widths.
The western part of the ore-body was widely developed by the room and pillar methods of stoping, and had unsupported openings. Company officials had also reported that the strike of the western ore-body was known to continue for a distance of 80 feet, In several case the company had supported this operation by developing roof bolts at the back of this stope.
Some more geological information had also stated that the eastern ore-body was mainly formed from faulting, and fracturing, which resulted in weaker back sections. Generally it was also stated that the stopes within the fault sections had been developed at a small size. This whole entire development procedure was also supported by roof bolting, and timber supports. Pillar supports are also used within the first level stopes as the ore-body is rather located near a swamp section. These conditions have place minimum of development on the first level stopes do to this down fall.
The information below indicates the total lateral development that was done on the levels to date.
There was also significant amounts of reserves that became outlined, and had totalled 700,187 tonnes of probable ore grading 2.62 pounds per a tonne of uranium. Diamond drilling within 1956, had indicated another 2,082,146 tonnes of reserves that graded 2.71 pounds per a tonne of uranium. Further indications had also calculated a total of 188,590 tonnes of surface pillar ore, which graded 3,09 pounds of uranium per a tonne. Another estimation had outlined 171,533 tonnes of possible ore, grading 2.11 pounds of uranium per a tonne. With further ore- reserves outline this had given the mine a total reserve estimation of 3,142,556 tonnes of ore, which had an average grade of 2.68 pounds of Uranium per a tonne. Nothing else had taken place during 1956, as the levels became extended to their limits, and new development had also taken place. As the mine continued to expand it was also reported that subsidiary company had started constructing more dwellings in Blind RIver, Ontario, Canada.
Mining operations at the Pronto Uranium Mine had continued to take place throughout 1967. In all production there was a significant amount of ore that became hoisted, and ended up totalling 505,700 tonnes of broken ore. A total of 472,900 tonnes of ore was broken in the stopes, another 30,000 tonnes had been broken in preparation of stopes, and 2,800 tonnes of ore was taken from development work. Grading of the ore that was milled during 1957, had assayed 2.55 pounds of uranium per a tonne. Several faults, and the degree in faulting had decreased in thickness of the ore. More so it was strongly reported that this had resulted in a gradual reduction in daily production per stope panel, although drilling and breaking efficiency was considered to have improved. It would also lead to an increase in roof bolting to maintain control of the backs within the fault areas. This also had resulted in an increase in the amount of stope preparation, and development work which was required per a stope panel. Production within the stope panel would also have to be increased in order to meet the quota. A new level was also cut and station on the mine 590 foot level of the No. 1 shaft The total lateral development on each of these levels is given below. Diamond drilling within this time period had also consisted of 12 surface holes, totalling 4,022 feet, and 19 underground holes, totalling 431 feet.
Further estimations of the ore reserves within the Pronto Mine had slightly decreased within this year. Most of this became cause because of dilution issues within the core samples, and the faulting that had decrease widths of the ore-body. But further drilling had improved these estimations when high-grade ore was encountered during diamond drilling. In total estimations it was reported that this mine had 824,421 tonnes of probable ore, grading 2.44 pounds of uranium per a tonnes. Some more drilling had also indicated 1,618,737 tonnes of ore that graded 2.32 pounds of uranium per a tonne. Even some of the pillars had also became added to the ore-reserves that totalled 197,634 tonnes, and graded at 2.31 pounds of uranium per a tonne. In total calculations it was also estimated to contain a reserve of 2,460,792 tonnes, which had a grade average of 2.36 pounds of Uranium per a tonne. This would give the company a total of 6,223,004 pounds of uranium.
It wasn't till 1958, when the Pronto Uranium Mine was once again going under extensive development phase. More so it became reported that another level was being cut, and stationed on the mines 742 foot level. The mine was also undergoing its very own development phase when a total of 19,219 feet of lateral work was done. Most of this development had consisted 6,871 feet of drifting, and crosscutting with the remainder done of box holing, and stope raising. Almost all development within that your was increased by 898 feet, and was done on opening up the lower level, and extra footage to develop small ore blocks isolated by faulting.
Shaft deepening within 1957 had started at the end of December, and was completed by April, 1958. There was also significant amount of expanding and development taking place during that time period of operating. It was reported that the Pronto Uranium Mine, Limited would extended the ore and waste pass system below the 742 foot level. Other installations which had taken place included installing a new ore-loading pocket, and a new main grizzly below that level to. Almost all this development, and installations was officially reported to have been completed by October, 1958. Some more changes that occurred was to improve the performance, and productivity of the tramway system. With the completion of shaft sinking it soon had increased production on what was known as the 590 foot level or the 5th level. Diamond drilling within 1958, had increased rapidly when a total length of 4,115 feet was completed from underground. Further predictions had stated that it was necessary to increase diamond drilling in order to gather more information on the structural faulting.
Company officials from the Pronto Uranium Mines, Limited would also hoist a large amount of broken ore that totalled 535,935 tonnes. For the most part it was stated that 95% of the ore taken was from stopes, and the remainder from stop preparations. Assaying of this ore had determined it to contain 2.54 pounds of uranium per a tonne of ore. The average thickness mined that year had been only extended to a width of 5.7 feet, compared to the 6.4 feet mined in 1957. Much of the stope sections within this operation had been mined by widths up to 5 or 4 feet within that year. In addition it was stated that the ore within these section had obtained high-grade ore from the narrow reefs mined that year.
All milling operations in 1958, had operated on a daily production rate of 1,507 tonnes of ore. In total production the milling facility had ended up treating 549,976 tonnes of ore that produce 1,297,943.36 pounds of uranium. All production that year was slightly increased do to acid concentration, and leach temperature. Some more predictions had also stated that the company had lost 37% reduction in tailing losses from previous years.
The total reserve within the Pronto Uranium Mine was now estimated at 1,808,448 tonnes of uranium, which graded 2.56 pounds per a tonne. For the most part it was reported that the decrease in the ore reserve was from information on development relating to the actual thickness of the reefs. Almost all the calculations had predicted 750,5128 tonnes of probable ore, grading 2.40 pounds of uranium per a tonne. Some more estimations had totalled 738,418 tonnes of drill indicated ore that graded 2.76 pounds of uranium per a tonne. At the time there was also another 319,502 tonnes of pillar ore reserves, grading 2.46 pounds per a tonne.
Some more work was continued in 1959, and was aimed determining the extension of the ore zone to the east. Surface diamond drilling also continued to take place within this time period, and a minor amount was done on the extension. Assaying from this area had soon revealed that there was negative results from all diamond drilling that year. There was also a re-calculation of the ore-reserves that had indicated 535,844 tonnes of proven ore reserves, grading 2.49 pounds per a tonne. Probable ore reserves within the Pronto Mine had also estimated 137,142 from underground development, grading 2.39 pounds, and 647,685 tonnes of diamond drill indicated reserves at 647,685, grading at 2.57 pounds per a tonne of uranium. In total estimation there was a reserve of 1,320,671 tonnes of ore with an average grade of 2.53 pounds of uranium per a tonne. Almost all development within 1959, had totalled 4,907 feet of drifting, 2,152 feet of crosscutting, and 380 feet of raising. The total development footage within this time period had totalled 24,350 feet of drifting, 10,103 feet of crosscutting, and 5,305 feet of raising. Diamond drilling had resulted in 191 holes from underground, totalling 9,976 feet, and 41 surface holes totalling 16,704 feet. Far more explorations also continued when the company had done 200 feet of trenching that year. Other major event had also occurred when the Pronto Uranium Mines, Limited had acquired all assets to the Pater Uranium Mines, Limited. Generally the whole entire uranium product was being contracted out to the Eldorado Mining and Refining, Limited, in which a new contract was made, and demanded for 1,508,000 pounds of uranium. Milling operations at the Pronto Uranium Mine had continued to operate through the year, and treated 576,690 tonnes of ore that year. Production from the Pronto Mill had produce a total of 1,320,620.1 pounds of uranium. By this time the Pronto Uranium Mine had shipped a total of 4,279,000 pounds of uranium to the Eldorado Mining, and Refining, Limited.
Mining operations at the Pronto Uranium Mine became shut down after a total of 149,528 tonnes was milled from January 1, to April 1960. Mining within the Pronto Mine had hoisted another large amount of ore that totalled 148,228 tonnes. Some more surface drilling was also done, and had consisted of 21 holes, totalling 1,643 feet from underground. Ore reserves at the pronto mine had been indicated at about 2,000,000 tonnes of ore grading 2.29 pounds of uranium ore. The Pronto Mine Mill was later converted into a copper concentrator in order to treat copper from the Pater Mine site for the next 10 years. All of this would take place from 1960 to 1970, when a road was created from the Pater Mine to the Pronto Mine Mill.
The Lower Mississagi Formation rather dips at 15 to 20 degrees south, and comprises of pebbly arkosic quartzite which it typical of the Mississagi Formation. Most of this rather grades upwards to much feldspathic quartzite with green band. At the base of this formation, in the intermediate mine area, lies the pyritic, quartz pebble conglomerate of the ore bed. Locally, in the mine there are patches of polymictic basal conglomerate but it does not form as a continuous horizon. A maximum thickness of 600 feet of Lower Mississagi rocks is preserved beneath the Pronto Thrust Fault. Near the top of the sequence, localized argillaceous lenses indicate the proximity of the boundary between the Lower and Middle Mississagi Formation.
The Algoman Basement Complex, is a block that overlays the Pronto Thrust Fault, and it was at one point in time that this was thought to be an intrusive offshoot from the Cutler batholith but it has since been disproved.
The Beaver Pond Fault is located in the southern boundary of the granite block that is marked by the Beaver Pond Fault, south of which lies the Upper Mississagi Formation. The relationship of the Beaver Pond Fault to the Pronto Thrust Fault is not fully known.
The typical ore and the only type seen at surface is pyritic uraniferous, quart-pebble conglomerate that's generally 60 to 10 feet thick, but locally 15 to 20 feet thick. However, its also through much of the mine where varying degrees of alteration are superimposed on the conglomerate and the associated quartzite of the Lower Mississagi Formation. There are generally three types of alterations that have been distinguished, albitization, chloritization, and carbonatization, which may occur separately or together. During early work the albitized rock was mapped as radioactive quartzite and the chloritized rock as radioactive grit in belief that they represented facies change in the ore horizon. And, by the time the true nature of the rocks were realized, in which these terms had become entrenched within the mine and have been retained by Pronto Personnel. Lithologically, the conglomerate consists of well rounded pebbles of quartz, quartzite, and occasionally chert embedded in a gritty matrix. The Quart Pebble are predominantly which and glassy, but bluish and banded grey one are also present. These foremost pebbles are remarkable uniform in size, and range from 1/2 inch to 2 inch in diameter. The ratio of the pebbles to matrix is also estimated at 65 to 35, in which the matrix of the conglomerate at the base of the series pyritized with concentration of pyrite varying considerably.
The typical rock of the ore zone is an oligomictic conglomerate characteristic of marine transgression over a surface of low relief. The term oligomictic applies to conglomerates noted, firstly, for their simple composition and, secondly, for the fact that the pebbles are of rock types that are resistant to erosion, such as quartz, quartzite, and chert. No granite boulders have been observed in the area of the ore-conglomerate, in which this phenomenon and the well preserved regolith observed north of the glory holes and in the mine workings attest to the efficiency of the Pre-Huronian weathering.
Pebbles are also generally well sorted, which occasionally occur in large pebble that have been observed dispersed along one or more specific horizon. The conglomerate is considered to be in lenses that is quite apparent near the fridges of the ore-body. Intercalated quartzite band also occur within the ore zone, in which some of these are traceable over hundreds of feet. These quartzite lenses and bands, and the hanging wall quartzites are more correctly described as sericitic arkosic sandstones. It also these sandstones that directly overlie the quartz-pebble conglomerate that contains pebbles of quartz within it, but are higher up in formation pebbles that are not present. Quartzite is known to also generally show crude-grade bedding, and crossbedding, which is usually of torrential type, that is moderately to well developed. Pyritic or chloritic seams are common along fractures which define the crossbedding in the quartzite. In addition, similar fractures and imbrication of pebbles define current structure in the conglomerate. Occasional bedding planes within the quartzite members show ripple marks. Its also generally the sediments near the granite contact are also arkosic sandstones showing little to no recrystallization and retaining their original sedimentary features. Its also to the south, over an interval where the sandstone becomes of tougher and more recrystallized, until eventually it is more correctly termed as quartzite.
Within the mine workings it was reported that four diabase dykes of mappable size transect the ore-bearing conglomerate. Observations in the area had also observed two dykes which cut basement rocks but not the ore zone, that these may be of pre-Huronian Age. These four dykes rather have a trends north-west except that to the south, which fills an east-west fissure. No uranium enrichment has been noted along any of the dykes, and the dykes may be describe individually:
Number 1 Diabase is an average width of 11 feet and dips north-east at 62-80 degrees. It has somewhat sheared margins but there is displacement. Its also un-faulted, Brecciated ore adjoining the dyke to the south-east is slightly altered, and to the north-west this dyke enters a lean area in the ore.
Number 2 Diabase has its own width that varies from 55 to 100 feet, and has a dip which also varies from 60-80 degrees. The margins are generally somewhat sheared and movement of the ore in relation to this break has occurred. It also the difference in elevation that's across the dyke in the north is negligible but there is a difference of 70 feet on the 6th mine level. Its also known to commonly interrupt a number of structures but not the others, and it drops on the east side. Its between the 4th and 5th levels where there is approximately 60 feet of lateral development. The structure at this point, is not exposed and in addition to a great deal of vertical and horizontal faulting has taken place.
The main types of waste generated by the mining and milling of uranium ore are tailings and waste rock.
Tailings are the waste produced by grinding the ore and the chemical concentration of uranium. When dried, tailings have the consistency of fine sand.
Waste rock is simply rock material removed from the mine to gain access to the ore. It has very little to no concentration of uranium.
Waste rock is separated into clean rock or mineralized rock, according to its mineral content.
Tailings and mineralized waste rock must be managed over the long term because they could contain significant concentrations of radioactive elements (primarily thorium-230 and radium-226, along with their associated decay products).
Tailings and mineralized waste rock are contained in engineered surface and near-surface waste management facilities located near the mines and mills.
During mining operations, clean and mineralized waste rock will be placed in separate rock piles, as each require different management practices.
Clean waste rock can be used for construction activities, such as aggregate in concrete and the construction of roads.
Clean rock that is left over once mining has ceased can be left in piles on the surface, contoured to blend in with the natural environment and revegetated.
Mineralized waste rock contains either low-grade ore with little value or significant concentrations of secondary minerals.
If left exposed on the surface indefinitely, this waste rock could generate acid or release contaminants at rates that could impact the local environment.
During operations, mineralized waste rock is deposited on impermeable pads.
Seepage and run-off from the mineralized waste rock piles are collected and processed through a water treatment plant to remove contaminants before they are released to the environment.
Wherever possible, mines are specifically designed to minimize the volume of mineralized rock removed from the mine and to return mineralized waste rock to the mine (as backfill).
Long-term management of mineralized waste rock includes depositing the rock in mined-out open pits, topping them with clean waste rock (or till) and covering surface piles with canopies engineered to minimize the infiltration of water and erosion.