Bauxite dust is produced in bauxite mining, resulting in air, water, and soil pollutions. The immersion of bauxite in water leads to a decrease in soil fertility and affects the sources of agricultural products and aquatic organisms.
We can get aluminum from bauxite beneficiation process, and the elements of residues in the process are iron oxide (10 30%), titanium dioxide (2 15%), silicon oxide (5 20%), and insoluble oxidation aluminum (0-20%).
Workers or those who breathe large amounts of aluminum powder may develop lung disease, such as coughing or chest problems. So, breathing masks and better dust-controlling skills are must-have to the miners.
Oral aluminum is generally harmless. Some studies have shown that people who take too much-containing aluminum a long time may develop Alzheimer's disease, but there is no much supportive evidence.
The World Health Organization has made a health guide to the maximum intake of aluminum. Each adult takes material with aluminum should less than 2mg per kilogram of body weight in one week. That means that if a 60-kg adult eats 120 mg of aluminum per week, it will never cause accumulation and impact health.
For children who got kidney disease, brain and bone diseases caused by high aluminum content is found in their body. In these cases, bone damage is caused by aluminum in the stomach, which prevents the absorption of phosphates- necessary compounds for healthy bones.
The substances produced during the bauxite mining process include dust, sulfur dioxide (SO2), and nitrogen oxides (NOx). The mining and beneficiation of bauxite do not involve the use of chemical reagents and produces no odors.
Concerning noise emissions, the main sources related to bauxite mining may include: engines of heavy equipment ( bulldozers, excavators, loaders, transport trucks); crushers and beneficiation equipment; conveyors; railways; bauxite loading, unloading and storage of power generation; bulldozers; and drilling and blasting.
If high-aluminum concentration of heavy metals in sediments are deposited in the water, it will further dissolve and deposit into fish and benthic creatures. That make the numbers of invertebrates 10-1000 times higher than in normal water.
Before mining and soil type classification, soil suitability should be evaluated and classified according to erodibility and stability for reclamation. Make soil management plan, which involves specific site processes
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The largest single producer of bauxite (aluminium ore) in the world, Cie des Bauxites de Guines (CBG) operations are located in the west of Guinea, close to the border with Guinea-Bissau. Since opening in 1973, the operations produced over 260Mt of bauxite for export.
CBG was established in the early 1970s as a 49:51% joint venture between the Guinean government and the Halco partnership, originally comprising a group of international aluminium industry participants. Since 2004, Alcoa and Rio Tinto Alcan have each had a 45% stake in Halco, having gradually bought out most of the other founder members. In mid-1999, the government invited Alcoa to take over management of the project.
The operations consist of the Kamsar bauxite treatment plant on the West African coast, and a group of open pit mines located 100km inland, centred on the community of Sangardi. Mine production rose from 12.2Mt in 2001 to just over 14Mt in 2005, with 11.5Mt/y to 12.5Mt/y of bauxite products being shipped from Kamsar. The operation is facing reducing ore grades as high-grade material is mined out.
In 2006, Halco reached an agreement with the Guinean Government over the development of a 1.5Mtpa alumina refinery at Kamsar. The original agreement, which was set to expire in November 2008, was extended to November 2012. Alcoa and Rio Tinto Alcan completed the pre-feasibility study in 2008. The commissioning date as per the previous original agreement was scheduled for 2009, with a price tag of at least US$1bn. The same has been rescheduled for 2012. The refinery will have a provision for capacity expansion of up to 4.5Mtpa.
Bauxite deposits are found across much of western and central Guinea, having been formed by the tropical weathering of underlying, aluminium-rich rocks. The deposits are typically close to the surface. Proven reserves total some 2,300Mt with additional probable reserves of 18,600Mt, most of which contains between 40% and 50% aluminium oxide (Al2O3).
CBGs operations are based on three main ore zones Sangardi, Bidikoum and Silidara, with further resources at the Ndanga, Boundou Waade and Paravi deposits. Each deposit contains several different types of ore, varying in both grade and physical properties.
Its existing resource totals over 300Mt grading 51% Al2O3, sufficient to support production at current rates for at least 25 years. Historically, grades in Sangardi have been 5658% Al2O3, while ore in Bidikoum averages 50% and Silidara 52%.
In 2006, CBG signed an agreement with the Guinean government and Global Alumina over granting Global Alumina access to some of the CBG bauxite reserve areas. In return, CBG will have future access to some 2,000Mt of bauxite resource that lie outwith its current concession.
While Sangardi was the orebody on which CBGs operations were founded, today between 85% and 90% of its output of raw bauxite comes from the Bidikoum and Silidara pits. After stripping any thin overburden, the ore is blasted and then loaded using hydraulic excavators into haul trucks for transport to the mine stockpiles.
Bench heights of up to 8m allow most of the ore to be mined in one horizontal pass. The mining fleet consists of Demag H185 excavators, Caterpillar 992C and 992D wheel loaders, and 17 Caterpillar 777B and 777D trucks.
Run-of-mine ore is stockpiled in long piles that run parallel to the mines rail sidings, with material from the different pits being tipped in layers to give a consistent blend. The stockpiles are then reclaimed using Caterpillar 992s that dump directly into rail wagons alongside.
Treatment of the run-of-mine bauxite consists mainly of crushing and drying before shipment. Ore wagons are tipped individually, the material being crushed to 100mm before stockpiling. After reclaim using bucket-wheel stacker-reclaimers, the ore is dried from an average of 12.5% moisture to 6.7% for shipping.
The jetty can handle Panamax-sized vessels of up to 60,000dwt, with around 230 such shipments of metallurgical-grade bauxite scheduled per year. In addition, CBG exports low monohydrate and small amounts of calcined bauxite, and has to import all its fuel and equipment spares through its own port facilities.
Alcoa has made substantial investments in the rehabilitation of the Kamsar plant, including new belt conveyors and dust-control systems, with the aim of increasing its export capacity to 13.5Mt/y of bauxite products.
Available alumina and reactive silica define ore grade and conditions for bauxite refining. Malvern Panalytical s predictive solutions help to efficiently sort and blend bauxite, ensure optimal and profitable extraction of available alumina, and support sustainable and safe waste management (red mud).
Our expertise and solutions range from direct conveyor belt analysis to laboratory analysis and complete automated quality control. We deliver tailored analytical solutions for exploration geologists, mine planners, process engineers, laboratory and quality managers as well as geometallurgists.
Our solutions for real-time monitoring on conveyor belts (elemental and mineralogical) with its fast feedback loops, enable fast counteractions on changing bauxite composition directly in the mine and effective ore sorting.
Optimal bauxite blends with constant composition secure optimal use of caustic soda and other reagents during refining and avoid costly processing of waste material. Control of the moisture content on the conveyor belt using near-infrared (NIR) technology, together with accurate monitoring of the composition of iron ore before shipment, guaranties constant ore quality to avoids penalties.
Our laboratory solutions, tailored to the specific requirements of your mine, provide accurate and fast information whether it is benchtop or stand-alone equipment or completely automated laboratories.
Our expertise in XRF sample preparation, especially to produce high quality glass disks using fusion machines, are the basis for accurate elemental analysis according to international norms. The use of modern technologies such as X-ray diffraction (XRD) to predict available alumina and reactive silica, reduces the need for costly, time intense and unsafe wet chemistry.
Efficiency of alumina refineries, minimal use of energy per ton alumina and highest recovery rates depend on bauxite composition, impurity level of the process liquor and optimal caustic soda consumption. Our portable and flexible elemental analysers are perfectly suitable to monitor impurity levels of bauxite and process liquors directs in the refinery even in remote areas.
Particle size and distribution as well as the crystallographic modification are key variables that define quality of alumina and directly impact the rate of dissolution of alumina in the aluminium smelters. To meet the required alumina specifications our on-line particle size analyzers are designed to operate in rough process environments. Economic benefits are: