The East Kemptville deposit is a greisen-hosted Sn-Cu-Zn-Ag-In deposit with the alteration and mineralization predominantly affecting the East Kemptville leucogranite (EKL). Three major lithologies (besides overburden) are recognized for the East Kemptville deposit. They are:
1. Leucogranite (EKL) intrusive which is primary host of the mineralization.
2. Within the Baby Zone, a contact zone which is a mineralized igneous breccia containing both metasediment and granite clasts.
3. Metasedimentary rock consisting of interbedded psammites and pelites.

Tin and base metal (Zn-Cu-Ag-W) mineralization within the deposit is primarily fine to medium-grained and is associated with northeast-trending, sub-vertical and zoned, quartztopaz, sulphide-bearing greisens, veins, and stockworks that occur primarily in the sericitesilica-topaz altered portions of the leucogranite meet the roof zone in contact with surrounding metasediments.

In many respects, the geometry of the mineralization over the areal extent of the deposit appears akin to a series of closely spaced jellyfish where the bodies represent wider zones of 51 intense fracturing and coalescing greisens near the top of the intrusion and where the tentacles represent narrower, higher-grade feeders or root zones. A structural control on the emplacement of the mineralization may help explain why some thicker (20-40 m) portions of the deposit occur at greater depths and why some thinner zones (2-5 m) occur at higher levels (i.e., northern portion of Main Pit). In general, the zones below the current pit appear to be thinning and are of higher grade.

The overall gross dimensions of the original potential economic mineralization at the Main and Baby Zones based on a cut-off grade of approximately 0.05% Sn are in the order of 1,500 m long, 350 m wide and 75 m to 150 m deep. Most of this volume is represented by the larger, Main Zone, which has been further subdivided into three subzones termed the Western Flank and South and North Extension Zones. The smaller and discrete Baby Zone occurs a few hundred metres southwest of the Main Zone within what is believed to be a structurally controlled, satellite intrusion. The intrusion hosting the Baby Zone is in the order of 250 m long and 50 m to 75 m wide, but may be continuous with that of the Main Zone at depth through the South Extension Zone.

Higher grade, thicker, mineralization in the Baby Zone is focused along its structurally controlled, southeastern contact with the metasediments and along an interpreted fault that continues northeastward through the Main Zone. Here, potentially economic mineralization reaches tens of metres in thickness and grades appear to average over 0.20% Sn, 0.30% Zn and 0.10% Cu.

The Main Zone mineralization is closely associated with ductile zones and greisens are predominantly restricted to fractures whereas the Baby Zone displays brittle deformation and has pervasive greisens below the wallrock contact.

Mineralization between the Main Zone and the Baby Pit is referred to as the Southwestern Extension of the Main Zone and is not exposed at surface but intersected in drilling.

Avalon plans to engage a locally (Eastern Canada) based mining contractor to mine material from the Rio Algom Ltd. (RAL) legacy stockpile, the Baby Zone pit and the Main Zone pit. This contractor will be responsible for supplying, operating and maintaining all mining equipment, trucks and mining related infrastructure. Avalon’s cost estimate has only budgeted for emptying the pits of both water and any sludge that may have settled on the bottom.

The mining will re-start as a continuation of the historic open pit operation using a conventional drill and blast process and conventional truck and shovel methods for material movement. Mill feed will be hauled to a small (24 h) stockpile and then reclaimed into the crusher rock box by a front-end loader. The mill treatment rate is set at 2,208 t/d (806,000 t/y) starting initially using only stockpiled material, which will then be supplemented by new feed mined from the Baby Zone Pit during production Years 2 and 3. Thereafter, mining will take place from the southern portion of the Main Zone Pit in Years 3 through 7, followed by production from two pits located in the northern portion of the Main Pit Zone in Years 7 through 14, after which the operation will be fed with the remainder of the legacy stockpile through Years 15 to 19. During Years 2 through 14 when the majority of mill feed is sourced from the pits, approximately 6 weeks’ worth of material will be scheduled from the legacy pile in order to (a) incrementally reduce the environmental liability and (b) maintain mill productivity in the event significant operational delays are encountered in the mine.

As per this study, inter-ramp angles up to 56° could be maintained with a double-bench interval of 24 m, provided controlled blasting and other practices such as drainage ditches, berm clearing, and scaling of faces are put in place.

Production benches will be drilled and blasted in 12-m bench intervals and excavated in 6-m flitches. The 6-m benches will be stacked up to 24 m.

Bench Heights - 12 m;
Bench Face Angle - 75°;
Catch Berm Width (Baby Pit Zone) - 12 m;
Catch Berm Width (Main Pit Zone) - 10 m;
Benches between Catch Berms - 2;
Inter-ramp Angle - 56°;
Overall Pit Slopes - 48°;
Ramp width, Two -way traffic - 22 m;
Ramp width, One-way traffic - 14 m;
Ramp Gradient, Two-way traffic - 10%;
Ramp Gradient, One-way traffic - 12%.

Crushing Circuit
The crushing circuit consists of a three staged crushing circuit and a series of screens for classification and magnets for tramp iron removal. Run-of-mine (ROM) material is fed at a rate of 200 t/h to a vibrating grizzly feeder (with 50 mm openings) by a front-end loader. Material greater than 400 mm is retained ahead of this feeder by a static grizzly screen and broken with a hydraulic rock breaker.

Material coarser than 50 mm is fed to a jaw crusher and then combined with feeder undersize before being classified at 50 mm by a vibrating primary screen. Primary screen oversized material is further crushed in a secondary cone crusher the product from which is combined with primary screen undersize and then screened at 8 mm by a secondary screen. Oversize (+8 mm) reports to a tertiary cone crusher before being recycled back to the secondary screen. The -8 mm product from the secondary screen is conveyed and stored in the fine crushed ore bin.

Milling and Classification Circuit
The grinding and classification circuit consists of a ball mill, a coarse screen and 6 “stacks” of fine screens (80 µm). The ball mill discharge is pumped to the coarse classification screen to remove +0.5 mm material which is recycled to the mill. The - 0.5 mm material is pumped to a 4-way distributor, 2 outlets of which feed continuous primary HSCC concentrators (space will be provided for installation of up to a further 2 concentrators in the future if necessary). Tailings from the primary HSCC concentrators are combined with the other 2 outlets from the distributor, along with recycled gravity table tails and cleaner 1 and 2 HSCC concentrate tails and pumped to the stack of -80 µm fine screens. Screen oversize is recycled to the ball mill while screen undersize is feeds the main HSCC gravity circuit.

The 100 tonne per hour operation to treat the mineral resources at East Kemptville consists of several conventional processes to produce a tin concentrate. The plant feed undergoes crushing in a three staged crushing circuit, milling and classification, and is then put through a series of gravity circuits using high-speed centrifugal concentrators (HSCCs), magnetic separation and flotation to remove the metal sulphide before going through a series of shaking tables.

Gravity Circuit.
Screen underflow from the milling circuit feeds a 2-way distributor with each outlet feeding continuous rougher HSCC concentrators in the gravity circuit. Tailings from the rougher concentrators are pumped to tailings. Concentrates from the rougher concentrators are combined with primary HSCC concentrates and fed to a primary cleaner HSCC concentrator. Primary cleaner concentrate feeds a secondary cleaner concentrator, the concentrate from which is pumped to a sulphide removal circuit. Taili ........