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Strategies & Market Trends : Winter in the Great White North -- Ignore unavailable to you. Want to Upgrade?

To: russet who wrote (3195)	10/2/2002 6:55:20 AM
From: E. Charters	Respond to of 8273

It depends on the tailings pond. Some are highly sulphidic or oxidic and are near rivers that have fish etc.. Others have stable berms, are simple ores with low sulphides and are not dangerous to aquatic life. We have the latter. It was a cyanide mill that created one of the ponds, but cyanide in a low sulphide environment is not locked up in cyanicides and has died eons ago. Decomposition releasing cyanide is not taking place. Cyanide is a non issue that the popular press bandies about because of some dubious engineering disasters of two particular operations that were really really badly designed in foreign countries with poor oversight. Both were near rivers and both were really high in cyanide which is bad planning and unecessary. Cyanide recovery was not being employed and that tailings dams were unstable in certain rainfall and earth movement conditions. There are 4 stages of cyanide recovery that should be employed. 1. is acidulation to recirculate or recover the cyanide from the effluent. This is the oldest technique and was pioneered by Mills Crowe in Flin Flon in 1930. 2. Then there is the permanganate process or the Inco iron process, that if correctly monitored still further reduces cyanide. 3. Addition of chlorine will get rid of cyanide as will sulphidation. 4. Finally there is exposure to UV light which require the reduction of sediment load and shallow ponds for light penetration. UV destroys cyanide. The ponds should be moated or dual ponded with high cyanide portions within a low cyanide outer discharge pond. This obviates outer wall breaches being dangerous. In addition water dahlias will collect metals and cyanide in streams. As a fourth process I have a theory on carbon deposition with charge that collects positive and negative ions both. This method is not yet commercially deployed. *********** Dealing with an old tailings pond itself can be done easily. If total recirculation is employed and there is no net overflow of process water, then no new tailings dam or (possibly) overflow ponds need be built. One can filter, centrifuge, settle and recirculate the water one uses in low-water type recovery apparatus. With containment stability of the process, the enviroment damage is kept to what it was with the start of the operation, and the risk of breach is low. Risk is also low because the operation is confined within the old berms and the process itself uses only gravity recovery and no chemicals, that if breach or overflow were to take place, would contaminate the environment. The pond no longer contains cyanide as the age is too great for cyanide compounds to have survived. In this scenario, no solids or water overflow the settling ponds, so the sulphides, which are low anyway, cannot enter the envirnment at large. Each type of recovery entertained has to be permitted on its own. Scale is important. Flotation chemicals have no guidelines or restrictions with environment because amounts are low and the chemicals themselves are mostly benign. Operations that process concentrates either by cyanides or nitrate process use very low amounts of total materal. A 1000 ton per day gravity-cyanide operation that cyanides a concentrate, would cyanide a mere, 15 tons (dry) of concentrate material a day. With that small amount of process water that would be necessary, the water could be treated and recirculated economically. Nitrating of concentrates could totally reuse water after treatment to ionically purify the water. This could be done as volume is very low,con grade is high and it is net cheaper than discharge to permit. So it ain't that hard after all. The subject issues and how we solve them are proprietary to Wildcat and cannot be further discussed or qualified for feasibility until people are legally constrained by agreements of confidentiality or are invested. We have access to catalytic air patents and water purification patents designed by consultants for Syncrude for tailings disposal. As well we have access to mills that used proprietary dry processes to obviate environmental concerns. Other methodologies of recovery and recirc are of our own design. We have studied the problems of Erocon, and Eastmaque and we know why these operations were uneconomic while the Kirland Lake Basin was. Both the high capital cost of the first two mentioned operations and their loss rate can be avoided by simple means. We operated a tailings pond recovery operation in Ontario, which we proposed because of perceived high loss rate of a flotation primary operation while employed as an assayer at a hard rock gold mine. This tailings pond recovery operations was experimental and had no assay lab, or concentrate treatment process, which is a fatal flaw. The tailings recovery unit was designed by the late Kelly Dolphin whose company proposed tailings pond operations to many companies in the early 1980's. It was a highly successful unit at making a concentrate. If con treatment had been parcel to that operation it might have come to full scale. An engineer, Clement Pasieka, and myself operated and tested the unit and general pond criteria in several ways. We found it is absolutely necessary to know your input (heads) and output (tails) pervasively to deduce the operational efficiency and balance of any plant of any size. This means full testing facilities and lab process on site. This cost is could be as low as 30K plus one trained assayer. It could be done even cheaper by rough methods, but testing has to be done assiduously. Another key that is not obvious to the non-milling-engineer is that electric pumps are on-off and not variable in flow. Recovery apparatus is fixed and not variable in capacity. Feed rates and density rates of pumped feed swing wildly, effectively making the dry flow rate extremely variable. This has to be controlled for and overflow, dewatering and surge capacity must be installed or the gravity apparatus will not function properly. Feed rates must be balanced precisely,matcehd to recovery apparatus real feed rates (about 1/3 of rated capacity ) AND equipment installed to allow for wide swings in feed rate. This could include density feed rate sonic controllers and bypass lines/tanks. Sound way complex? Not really. But it should be an integral part of design. ( Yes, you have to use 3 times as many watchamacallit recovery units as the company says you have to in order to handle your feed rate. you would think they were on to this. Knelson, Reichert, Gemini, and Wilfely are all the same. Omly the pumping people have it down pat as to rates. ) At Eastmaque and Erocon they complained about fine organics causing problems with their flotation. As well, the heat of their mills caused oxidation of the sulphides and trashed flotation. They could not grab the gold. There are several practical solutions to their problem as well. Since the engineers of these operations are of high degree and have to salvage their reputation, they make it sound like tailings operations are all uneconomic. So -- if that is the case, why do the South Africans have one the world's largest mines - a tailings operation in Johannesburg? Why did they make money? Why did Kinross make money in Kirkland Lake? Why do placer miners make money with even lower grades and even harder detritus moving problems? Ah-ha!. So it can be done. I think Erocon and Eastmaque painted themselves ina corner that they had never painted before and they could not paint themselves out. I have operated in a plant that used flotation with gold. It worked. 92% recovery. I could do it. One of the keys is deoxidation and avoiding high heat enviroments. The polish grind they tried at these two operations compounde their problems as it caused rapid oxidation at the high PH. We used a chemical to do get around that but we were not trying to polish grind. In polish grind, the temperatures of the mill approach 212 degrees F. I know several cehmicals however that would work to descale the sukphides. (If you would like to know them ask me after I am dead.) The South Africans tackled it with PH. The other key might be controlling fine organics if you have them. This is rather fudgy but I believe it is tacklable by several absorpto-precipitative methods. The other way is not to float or grind. Amazingly simple. Perhaps it could be tried. Maybe. I dunno. Maybe its too easy. If it works and you are forced to sell 80 million dollars worth of equipment I would not cry about it. EC<:-}

To: russet who wrote (3195)	10/2/2002 10:08:04 AM
From: E. Charters	Read Replies (1) \| Respond to of 8273

Factotum # 37 in a series on how do we find the gold in this here hill structure? 1, Our assay method is bad. Its recovery is 30% or worse. We have to crush the rock by a hammer and pan. We weigh the gold we get by a scale to the nearest 1/20 of a gram. this requires huge 50 pound sample sizes. As there is only 0.75 grams in our sample and we get 30% of that for a measly 0.25 grams. There is no way of testing this because we can only guess at it. If we had a perfect assay method to test, we would use that. 2. We are concerened about our sampling method being representative but the only thing we can do is cut across the known gold precipitative structures to get as large a sample of them as possible. This requires channelling across the vein roughly sub parallel to the veinlets which cross the main quartz structure at 35 degrees to the strike. (D. Hume -- northwestern Ontario gold deposit) We do a channel every 7 feet and pray it works. 3,. Our mill has an unknown recovery too. It may be 40% and it may be 80%. Can we tell? If we run the ore we have sampled we only get to know there is a discrepancy between our assays of it, and the mill's recovery. Which is worse? 4. We do the same assaying of the mill heads and tails, and cons taking 50 pound samples every 3 tons, by collecting them carefully in small increments as unbiased a way as possible. We can only know that whatever the loss rate of the mill we have to increase the size of the tails sample to 250 pounds, as it may be that the mill takes 80%. In order to get the same accuracy we have to get 5 times the material. With all these things being the same, we now know the loss rate of our mill, as the accuracy of the tails assay has to be the same as the heads, so the relative losses are constant. With C-T/F-T we know the ratio of concentration. We can say we get 90% of the gold by smelting our concentrate, so we know the amount that went to tails. Smelting here is assumed to be our friend. We have to have friends somewhere. The last variable is the variable of our sampling versus the mill recovery. We now know that and the nugget effect or sampling variability can be calculated. By pan. In fact the pan is BETTER than fire assay of smaller samples. Why? Because it eliminates variability of the sampling size. We take 800 times more material, and the constant loss rate of the assay method and its crudity are more than made up for by bulkosity of the sample. That is why in 1975 they panned the tails of the Canadaka Silver mill flotation cells, and visually inspected the result to determine the efficiency of their flotation operation for silver. I believe the silver flotation method at Cobalt was the first such one employed and figured highly in their mining economics. EC<:-}