Aktyubinsk (Aktobe) phosphorite-bearing basin

AKTYUBINSK (AKTOBE) PHOSPHORITE-BEARING BASIN (RU: Актюбинский фосфоритоносный бассейн) is located in the Aktyubinsk (Aktobe) province of the Kazakh SSR. The length is 400 kilometres from the middle flow of the Emba river at the south to the Orsk city at the north, the width is up to 60-80 kilometres. The area of the basin is 25-30 thousand square kilometres.

The Aktyubinsk phosphorite-bearing basin is intersected by the railway lines from the north-west to the south-east (Aktobe - Kandagach - Chelkar) and from the south-west to the north-east (Guriev - Kandagach - Orsk). There are mature (common) in the Aktyubinsk phosphorite-bearing basin the phosphorites of the nodular type. The total reserves of the Aktyubinsk phosphorite-bearing basin are 700 million tonnes of the P2O5, including the explored (mainly at the Chilisai deposit) 112.6 million tonnes in the A+B+C1 categories, and 47.3 million tonnes in the C2 category of the P2O5 (1980). All reserves are suitable for the open pit mining.

The numerous phosphorite places of the Aktyubinsk phosphorite-bearing basin are grouped mainly in the three large deposits: Chilisai in the central part, Pokrovskoe at the west, and Alga at the north-west.

The phosphorites in the Aktyubinsk phosphorite-bearing basin have been discovered in 1890 by F.Yu.Levinson-Lessing; the geological researches were performed in 1903-06 and 1913-16, the most intensively in 1928-43. The extraction of the phosphorites has been started in 1929 at the Kandagach place, and at the Novoukrainsk place since 1934. The phosphorites were sent for the processing to the plant at the Alga railway station; the development continued intermittently until 1943. The new stage in the study of the Aktyubinsk phosphorite-bearing basin pertains to the 1950th-70th. There has been identified, studied, and explored in details the Chilisai deposit, on the basis of which the construction (1975) of the Chilisai phosphorite mining-beneficiation enterprise has been started. The Chilisai deposit is stretched meridianally for the 60-70 kilometres, the width is up to 20 kilometres, the area is 1.5 thousand square kilometres. The overburden is represented by the Campanian clays for the one third part, and by the Quaternary loams and sandy loams for the two third parts. The phosphorite layer lies horizontally at the depth of the 0-15 metres, of the thickness of the 0.8-0.9 metres on average; it comprises the solid phosphorite plate (the thickness is 0.05-0.4 metres, 0.2 metres on average), which is mature (extends) on the 40-50% of the area of the deposit, and the loose (nodular and gravel-pebble) layers. The phosphorite ore contains 9-11% of the P2O5 on average, and harmful admixtures, namely, Fe2O3 (2-4%), Al2O3 (2,5-4%), CO2 (2-5%). Depending on the content of the harmful components, there are identified the varieties of the ores: the easily beneficiated slightly ferrous one with the content of the Fe2O3 of less than 3%, of the CO2 of less than 3.5%; the ferrous one with the content of the Fe2O3 of 3.8% on average; the carbonatic and carbonatic-ferrous ones with the content of the CO2 of 4.5-5.2%, of the Fe2O3 of 2.7-3.6%. There is designed the transport-less system of the development with the usage of the walking draglines, and with the usage of the self-propelled scrapers in the zones with the overburden of less than 2-3 metres. The transportation of the ore is performed by the automobile transport to the equalizing warehouses (sorting yard), by the diesel locomotives from the warehouses to the bunkers of the beneficiation plant. There is planned the reclamation of the processed areas with the laying of the soil layer, which has been removed and displaced in advance, by the scrapers. The total marketable extraction of the P2O5 from the ore is 62-65%.

The 1st phase of the Chilisai enterprise (1985) provides the annual extraction of the 5 million tonnes of the ore, and the production of the 1.4 million tonnes of the flotation concentrate, with the production from it of the 1,140 thousand tonnes of the ammonium phosphate (46% of the P2O5).