some info on bulk sampling.

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Bulk Sampling

Before actual mine development, bulk samples are usually taken to more accurately establish the grade of the ore. Bulk sampling can be done from surface, or through sinking of an exploratory underground shaft. Bulk sampling usually involves the removal of large volumes of ore.

Bulk samples range from one tonne to 1000 tonnes or more. Test milling procedures may be done in laboratories using small samples, in test plants available in certain localities, or in pilot mills erected to mill pre-commercial quantities, such as 100 tonnes per day. [14]

In Ontario, for projects between ten tonnes and 1,000 tonnes, operators must obtain a “letter of permission”. The written application must describe the materials that are to be excavated, the amount of material, the excavation methods to be used, and what rehabilitation will be done. A financial assurance must be provided for the greater of $500 or $1.00 for each tonne of the material to be excavated. The financial assurance will be returned following receipt of a final report, unless it is “proven” that the rehabilitation work was not completed.[15]

Under Ontario’s mining laws, bulk sampling of over 1,000 tonnes passes an exploration project over the regulatory threshold and makes it an “Advanced Exploration Project”, with requirements to develop and file a closure plan with the Ministry of Northern Development and Mines and provide public notice that the project is underway.

In British Columbia, bulk sampling can be done under a “Notice of Work” for “Small Mines and Exploration Projects” which is filed with the Mining Operations Branch District Manager.[16]The “Notice of Work” requires a very general and brief descriptions of locations, equipment, and reclamation work. If bedrock excavation is to be 1,000 tonnes or more a program for predicting and managing acid mine drainage and metal leaching must be provided.[17] Only sampling which results in the extraction of an amount equal to or greater than 10,000 tonnes of mineralized rock must comply with Part 10.1.2 of the B.C. Mining Code.

In bulk sampling, the line begins to blur between mineral exploration and mining. Bulk sampling is often underground exploration, and often requires sinking a mine shaft or driving a “decline” or mine adit into a hillside (essentially, a mine adit is a horizontal mine shaft). [18]

Underground exploration investigates the continuity of the mineralized zone, and provides information about rock stability and structure and possibly water flows. From the explorationist’sperspective, the bulk samples allow extensive metallurgical studies and test milling. [19]