Alam et al. /Int.J.Econ.Environ.Geol.Vol. 10(4) 25-29, 2019 25 c The Process Designing of Gold Extraction from Placers of Passu to Shimshal (Hunza Valley) Gilgit-Baltistan by Mercury Amalgamation and Cyanidation Leached Method Muhammad Alam 1 , Javed Akhter Qureshi 2* , Garee Khan 2 , Manzoor Ali 3 , Naeem Abbas 4 , Sher Sultan 2 , Asghar Khan, 2 Yasmeen Bano 5 Government Degree College Gilgit, 1 Department of Earth Sciences, 2 Department of Physics, 3 Department of Mining Engineering, 4 Department of Mathematical Sciences, 5 Karakoram International University, Gilgit, Pakistan *E mail: javed.akhter@kiu.edu.pk Received: 22 October, 2019 Accepted: 03 January, 2020 Abstract: Gold wash through panning or washing in the fluvial sediments or sands is done on the river banks in Skardu, Hunza and other places. The method of gold washing is very crude, primitive and most of the gold is washed away back into the river. The current study mainly focused on extraction of placer gold deposits. Pneumatic machines from Passu to Shimshal (Hunza valley) Gilgit-Baltistan. The mercury amalgamation and cyanide leached methods have been used for placer gold deposits extraction from the concentrate obtained from shaking table. The amount of gold recovered from amalgamation method with mercury was 30.9%. The alloyed gold with other metals, gold dust, and fine gold was recovered by chemical process. The reagent consumption, i.e. 1.4 kg/ton of NACN and 6 Kg / ton of CaO were used for extraction of placer gold deposits. The extracted gold is 10.24 g /t and silver 22 g /t and the remaining gold like the amalgamation residue, tailings and middlings are extracted by cyanidation leached method. The extraction of gold by cyanidation process was compared graphically, and study results revealed that extraction of gold using cyanidation leached method was 91.40% and silver 100%, respectively. Keywords: Shaking table, amalgamation, cyanidation, recovery. Introduction In history of extraction of placer gold deposits, extract in various regions of Gilgit-Baltistan (GB) along Indus river basin, most of the gold is collected from the placers of these areas and fed to the market in Gilgit- Baltistan (Alam et al., 2018). Minerals like metals (gold), dimension stones (marble, granite, gemstones) play a vital role in the economy of GB. Thousands of families are involved in this industry and contribute a major portion to the economy of Gilgit-Baltistan, Pakistan. Gold extraction is a common practice, gemstones are mined from different localities, marble and granite industry is also developing day by day in GB. The heavy metals present in the gold concentrate may also be recovered by using modern methods on small scale, usually which are thrown into the river amalgamated with mercury, which affects the environment. Austromineral carried out studies during 1975-76 with the objective of proving the feasibility of at least one economic gold placer deposit, having a daily output of 5000 tons of alluvial gravel/sand, assaying about 0.3 grams of gold per ton. The method of mercury amalgamation used for gold extraction from placer gold deposit is a common practice worldwide (Veiga et al., 2006). The alternates of placer gold are Chlorination, Bromine leaching, Thiourea leaching, Thiocyanate leaching and Selenic acid (Bamzai and Shukla, 1999). The mercury-free techniques are environmentally friendly but are highly expensive (Hylender, 2001). The processing of placer gold is suitable by gravity separation and followed by mercury amalgamation (Shah, 2004). This method is effective for gold extraction of larger particle size, while cyanidation is effective for the recovery of finer particles, dissolved and alloyed gold. It is reported that shaking table is the most appropriate gravity separator for the recovery of fine-grained gold on the basis of specific gravity (Mitchell, 1997). The main objective of the study was to design a process for the extraction of gold from the placers along the Shimshal river from Passu to Shimshal. Study Area The study area widely extended from northern part of Pakistan and situated in between the great Karakorum Mountain Range of (GB) bordering with China and Afghanistan. Geological units exposed in this area are Passu slates, Kilik Formation, Gircha Formation, Gojal dolomite, and Karakorum batholith. GB is situated in the northern part of Pakistan extreme north of Pakistan bordering with China, India, and Afghanistan covering an area of 72,496 km 2 (27,799 square miles) with elevation varying between 1000 m and 8,611 m ASL. In this region land uses included glaciers (28.7%, n=72496 km 2 ), agricultural land (1.36 %), forests (3.2 %), rangelands (grasses, shrubs etc.) (32 %), barren lands i.e., rocks, clips and bare soils (34.4 %) and others including streams and rivers (0.43 %) of total area (Khan, 2013). Geology of the Study Area Shimshal valley is famous for gold recovery from Open Access ISSN: 2223-957X Int. J. Econ. Environ. Geol. Vol. 10 (4) 25-29, 2019 Journal home page: www.econ-environ-geol.org Copyright © SEGMITE