The Juruti area is located in the lower part of the Amazonian basin, south of the Amazon River, between the Guyana and Brazilian Shields. Parent deposits which form the base ofthe bauxite sequence belong to the Alter-do-Chao Formation comprising continental sedimentary deposits that accumulated in a fluvial-lacustrine environment and consist ofsandstones, siltstones, mudstones, and quartz breccias. Bauxites are known to have formed during intense lateritic alteration of the Cretaceous (145 to 66 million years ago, Ma)siliciclastic parent deposits which is estimated to have occurred during the Eocene (56 to 34 Ma). Cretaceous deposits were later covered by tropical soils as a product of rootactivity resulting in a kaolinitic and alumina-goethite deposited during flooding events in the Miocene (23 to 5 Ma).

The evolution of bauxite in this region is generally accepted to have occurred through a combination of intense weathering and geochemical alteration, leaching by meteoricwaters, and accumulation of alumina and iron-rich horizons, in addition to periodic erosion and redeposition of upper horizons. These horizons form gently undulating plateausranging from 100 m to 170 m above the level of the Amazon, surrounded by drainage erosion channels. While these plateaus cover extensive areas both north and south of theAmazon, not all are bauxitic, despite being within the same geomorphological and climatic area on top of the same sedimentary formation.

Cretaceou ........

The Juruti Mine operations are based on the use of conventional strip mining. Each plateau is divided into panels and regular strips of 20 m width x 200 m long within which anumber of sequential mining activities including land clearance, topsoil removal, overburden stripping and waste backfill, and bauxite mining take place.

The majority of the waste is backfilled by pushing the overburden back into the previously excavated cut with dozers. A suitable period of drying and consolidation of the fines isallowed before overburden is replaced. The returned overburden surface will be contoured with dozers to create an acceptable final topography. Shortly thereafter, topsoilstocks will be distributed over the overburden in preparation for landform rehabilitation.

The depth of excavation at Juruti is shallow (20 m or less) and the method of overburden removal by bulldozersresults in shallow slope angles. The geotechnical aspect of mine design is therefore not a major consideration for the deposit and a formal geotechnical investigation has not beencompleted for the open pits.

The mine is an open pit operation and uses on-road 8x4 40 t trucks, hydraulic excavators 66 t and 74 t operating weight and D6 to D11 size dozers.

The Capiranga plateau is currently being mined and will be shortly followed by Capiranga Central and Mauari plateaus.

The mining concept is based on conventional strip mining. Each plateau is divided into panels ........

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