TABLE OF CONTENTS

INTRODUCTION
CUPELS AND OTHER LABORATORY REJECTS
REGULATION 309 LEACHATE TESTS
SUGGESTED ACTION
POSSIBLE DISPOSAL OF CUPEL-BEARING MATERIAL
APPENDIX
SUMMARY AND CONCLUSIONS

INTRODUCTION

The Timiskaming Testing Laboratory has, through the years, followed industry standard practice and disposed of used fire assay cupels by dumping them at convenient locations near to the building.

The cupels contain about 30% Pb on average or 20g to 40g per cupel. The lead is present as the oxide, PbO, a relatively stable compound in nature.

Regulation 309 leachate tests on two samples that contain discarded cupels returned Pb values of 15.4 to 148mg/L, with a re-assay of sample TTL-91-1 giving 148mg/L Pb. The definition of hazardous waste, based on results of the standard Reg. 309 Ieachate test, is any material which produces a lead value >100 times the drinking water standard of0.05mg/L(>5mg/L or 5ppm).

The results of treating samples from both the south end and the north end of the TTL building indicate additional attention is required.

CUPELS AND OTHER LABORATORY REJECTS

Used cupels and broken crucibles have been dumped near to the Timiskaming Testing Laboratory building. This was standard industry practice since there was no indication that these items would cause any sort of problem. The crucibles are ceramic and were treated as just so much broken pottery, and the cupels in much the same way.

Both were incorporated into the fill in the parking lot and the roadway, or dumped over the bank where they accumulated to an unknown depth. Others were moved by water, snow ploughing, construction, et cetera, to new locations in the general area.

Broken crucibles from other fire assaying operations have been subjected to standard Reg. 309 Ieachate testing, and Pb values were consistently below the acceptable limits. This suggests that crucibles do not present a problem and, in any case, will not account for an appreciable volume of laboratory trash.

REGULATION 309 LEACHATE TESTS

Two areas in which cupels were evident were sampled by stuff of the Timiskaming Testing Laboratory. Sample TTL-91-1 was taken from the north end of the building, sample 91-2 came from the south end of the building. In addition, sample 91-3 was collected to represent "oxides" material from near the siding at the back of the building.

Results of Reg. 309 standard leachate test for lead are as follow:-

There is no explanation for the differences between the first assay of sample TTL-91-1 and the repeat value.

All values, including that for the "oxides" material, are above the limit for hazardous waste. The "oxides" are from the sample preparation equipment, and consist of "rust" from the various pieces of machinery. The oxides have been assayed and are found to contain:-

SUGGESTED ACTION

The property and any adjoining areas where cupels are identified should be sampled to determine the Reg. 309 leachate test results and a program of remediation undertaken such as may be indicated by these results. The number of samples will depend on the area observed to contain appreciable quantities of cupels. While thirty samples are usually necessary to establish the characteristic distribution of any population, it may be possible to gather the data necessary for outlining the area for remediation with fewer samples. However, it is not likely that less than 10 to 15 samples should be considered.

The samples for this study should be large enough to contain ten cupels, or the equivalent of ten cupels, each. The cupels have a tendency to disintegrate when wet and may not be present as easily identified items in some of the material.

The Reg. 309 leachate test requires that solid material be broken to pass through a 9.5mm (3/8") sieve. However, the Regulation stipulates collection of about 10U grams of sample, and the treatment of 50 grams in 1L of solution, for the test. This will introduce a sampling problem. One average small used cupel, in tact, will weigh about 50g, and have a specific gravity of about 4.8. There are only twelve 3/8" (cubic) pieces of cupel in this weight. If half the sample weight is barren rock, the law of tens will not be satisfied.

There does not seem to be a minimum grain size stipulated in the Reg. 3U9 leachate test. Therefore, to avoid sampling problems, we suggest that the law of tens be observed when field samples are taken. This means samples must be large enough to contain an expected average of ten cupels. The actual adequate field sample weight will have to be determined by observation. "Low grade" material must weigh more than "high grade". For example, samples of fill which is 50% cupels by weight need be only about one kilogram. If cupels are rare, say one per kilogram of fill, the samples will have to be at least ten kilograms each.

The field samples can then be crushed to pass 10 mesh (2mm"). (Each 50 gram cupel will give a minimum of ~ 1300 2mm x 2mm x 2mm pieces. There will actually be many more pieces since, if the maximum grain size is 2mm, the average size will be less than 1mm with the result that the cupel pieces will be about 8 times the minimum given above).

If the sample weight is made up of 50% barren rock, the sample will satisfy all sampling requirements. In fact, samples containing as little as 1% cupel material will still be valid at this mesh size, providing of course, that the field sample was properly adequate.

Analysis of the properly collected and prepared samples should include other metals listed in Schedule 4 of Reg. 309, since elements other than lead may pose some problems. Not all samples need be tested for the full suite of metals, but at least one each of low, medium, and high, lead content should be subjected to the full analytical treatment for metal content. There is no evidence of organic chemical contamination, but due diligence may require investigation to confirm or deny presence of such compounds.

Additional action will have to depend on the results of the environmental audit of the grounds of the building, and any adjacent areas that have been affected.

POSSIBLE DISPOSAL OF CUPEL-BEARING MATERIAL

We have investigated disposal of the cupels and cupel-bearing fill.

Finely ground cupels can be substituted for lead acetate in cyanide extraction of gold and silver. The lead acts to precipitate sulphide ion and permit more efficient precipitation of gold in the recovery section of a MerriIl-Crowe plant, for example. Many mines simply add used cupels to the grinding circuit.

The lead oxide in the cupels may be recoverable by smelting in a furnace designed to treat lead oxide ores and concentrates.

There are two metal processing plants in southern Ontario that have expressed an interest in testing samples of the cupel-bearing material to determine if they can be processed for contained lead without interference in their established circuits. We suggest that this possibility be investigated. Each organization will require about two kilograms of cupels.

Another possibility would be to ship "high grade" cupel-bearing material to an oxide lead ore/concentrate smelter.

It is not possible to have a firm answer from any of the potential recipients of the cupel-bearing material until the lead content has been established.

Some portion of the fill will probably contain insufficient cupels to yield a Reg. 309 leachate with lead content above 5-Omg/L, and may be left in place. There are areas, however, that will require excavation and removal followed by replacement with clean fill.

Material which does not contain enough lead to be of interest in some form of re-use, but containing levels of lead sufficient to yield a Reg. 309 leachate test above acceptable limits will present the greatest difficulty in terms of disposal. Acceptable handling of such material will have to be done on the advice of the Ministry of the Environment. When sampling and assaying has developed information that outlines all the problem areas, this possible situation can be persued further.

When the nature and extent of the cupel-bearing material is established by sampling and assaying, a course of action can be designed that will satisfy environmental regulations, and perhaps be cost-neutral. Further recommendations must await such additional data.

APPENDIX

Regulation 309 - Leachate Quality Criteria - Selected Metals

Any material that produces a leachate that is more than 10U times the concentrations given in Schedule 4, 0. Reg. 309 is considered leachate toxic, and classed as a hazardous waste.

The 0. Reg. 309 standard leachate test involves tumbling 50 grams of material for a period of 24 hours in a 1L of acetic acid solution having a pH of 5.0 ± 0.2.

The acceptable metal concentrations (drinking water) are as follow:

If leachate metal concentrations are greater than the following values the material is considered to be hazardous waste.

SUMMARY AND CONCLUSIONS

During the years since operations began at the present site of the Timiskaming Testing Laboratory in 1942, fire assay cupels have been disposed of by simply dumping on the ground at convenient locations around the building. Some have been incorporated into the fill at the north and south ends of the building, others appear to have been paved over in the parking lot, and in the roadway to the siding and station yard.

The cupels contain lead, probably mostly as lead oxide. The cupels themselves average about 30% Pb. Regulation 309 leach testing of the cupel-bearing fill indicate leachable lead in all of the three samples tested to be greater than 5mg/L.

The quantity of cupel-bearing fill is unknown. A series of test holes will be required to establish the extent of the area affected.

Portions of the cupel-bearing fill may, as a whole, give acceptable leachate test results, particularly if it is found that the quantity of cupels in tile fill is low.

In the event that it is necessary, disposal of the cupels may be achieved in several possible ways.

• Finely-ground cupels can be used as a substitute for lead acetate addition to gold recovery circuits that use cyanide extraction.

• Provincial Regulation 309 does not classify the cupels as hazardous waste if the material is being transported for recycling, or if the cupels are offered for sale to meet a realistic market demand.

• If the cupels are to be used in a gold mill or sent for recycling, they are then treated as a consumer product or as raw material and are exempt from registration and all other provisions of Regulation 309. Any shipment to a lead smelter, refiner, or similar establishment will fall into this category.

Two metal processors in the Toronto - Hamilton area have expressed an interest in testing samples of the material to determine if it would be a suitable feed for their plants.