Mines in West Africa, Sierra Leone capital Freetown 270 km south-east, close to Moyamba and state areas near the Atlantic coast Xiebu Luo Island, Sierra Leone alluvial placer generation in the Tertiary and Pleistocene expected exploitation of rutile There are more deposits. Currently mining is the Mogbwemo deposit with the largest reserves and the highest grade. The top grade of the deposit has an average TiO 2 content of 2.5%. The rutile content of TiO 2 is greater than 2% throughout the ore. In addition, there are also associated zircon and titanium, iron ore, due to less, not yet exploitation. The mine uses 0.68 m 3 multi-bucket sand mining vessels. There are 68 hoppers on the ship, the excavation speed is 26 buckets, the excavation depth is 15.25 meters below the level, and the horizontal plane is 6.1 meters. The excavation capacity is 1,445 tons per hour, the ship weighs 2,700 tons, and the installation power is 4,200 kilowatts. It is powered by a shore power plant with a 13.2 kilovolt cable. In addition, there are some auxiliary equipment for mining, including: one D7, D9 bulldozer; three D8 bulldozers; one Cat-950 loader; one Manitowoc 150Terane grader; two 38B mobile cranes; Dodge water truck; two 12-ton hydraulic cranes. The mined mine was first washed with a 5.74 m × 6.71 m scrubber and then fed to the other two scrubbers for a second wash. The fine fraction discharged from the scrubber was sent to 16 Darrick high-frequency vibrating screens for screening. The +1 mm material was sieved as tailings, and the sieved material was passed through a diameter supported by a floating frame. A 610 mm pipe is sent to the floating wet wet plant. The floating plant is a separate vessel, which is 600 meters away from the boat. The floating selection plant on the water carries out the first stage wet selection, and the second stage wet selection is carried out on the shore shaker selection plant. The ore sent to the floating wet separation plant is first dewatered by a two-stage hydrocyclone. The bottom flow size of the cyclone is -1 to 0.063 mm, the grade is TiO 2 2 to 4%, and the dry ore is 580 tons/hour. After sorting by 20 Reicert cone concentrators , the concentrate grade was increased to 48-51% TiO 2 . When the concentrate volume is 34.5 tons, it is transported to the onshore storage mine by a Zimpro high-pressure pump through a 7.62 cm (3 inch tube). The storage yard can store 10,000 tons of shaker. The onshore shaker selection plant consists of four eight-chamber hydraulic classifiers. The first stage wet selection concentrate is fed into the classifier for classification, and then eight sets of three layers, the Sterling 999 shaker and the shaker concentrate grade are fed. It is increased to about 70% of TiO 2 and the heavy mineral content is 95%. The heavy mineral composition of the shaker concentrate is rutile, pseudorutile, zircon, ilmenite, monazite, garnet and a small amount of quartz light minerals. The shaker concentrate is filtered, dried and sent to dry selection. The filter uses a 2.44 m diameter horizontal Dorr-Oliver filter. The drying is carried out in a rotary kiln with a diameter of 2.2 m and a length of 18.3 m. The rotary kiln is directly heated and the furnace temperature is 425 ° C. Diesel is fuel and has a drying capacity of 25 tons per hour. The temperature of the material discharged from the rotary kiln to the dry selection plant is 150 to 175 °C. Into the dry ore, a few sections of the Corpco high-pressure (28 kV) roll-type electric separator, making non-conducting minerals (zircon, quartz, monazite and garnet) and most of the conductor minerals ( Rutile and ilmenite are separated. The rutile and ilmenite are then separated by a few stages of screening and induction roll magnetic separators. Due to the difficulty in separating zircon and rutile, eight MDL plate electrostatic concentrators were deployed in the process in 1980, which ensured product quality and improved recovery. The dry-selection plant treated 18.7 tons/ton of ore, and the rutile concentrate yield was 13.2 tons/hour. The concentrate grade was TiO 2 96%, and the content of ZrO 2 and Fe 2 O 3 was less than 1%. The production process of the 100,000-ton rutile concentrate plant in Sierra Leone is shown in Figure 1. Figure 1 Production process of 100,000 t rutile selection plant Tungsten electrode, which is made of tungsten electrode with high melting point, corrosion resistance, high density, good thermal conductivity and conductive material. Tungsten electrodes are widely used for welding in their properties. Tungsten electrode grinding or polishing and black bar. The final color is different, you can distinguish the difference. In the tungsten electrode, more importantly, their final color is different, tungsten content is also different. When welding, select the correct tungsten electrode, make welding easier, it is important to get high quality welding. Some important factors to consider in making the right choice are power (inverter or transformer), welding material (steel, aluminum or stainless steel) and the type of material thickness. Tungsten Electrodes ,WT20 Tungsten Electrode,TIG Tungsten Electrode,WP Tungsten Electrode Changzhou Edaweld Trading Company Limited , https://www.edaweld.com
Due to the characteristics of tungsten, making it very suitable for TIG welding and other similar work of this electrode material. The addition of rare earth oxides to the metal tungsten to stimulate its electron work function, making the tungsten electrode welding performance can be improved: the arc of the arc better performance, better stability of the arc column, the electrode burn rate is smaller. Conventional rare earth additives are cerium oxide, lanthanum oxide, zirconium oxide, yttrium oxide and thorium oxide. Tungsten Inert Gas (TIG) welding is a popular type of welding that utilizes tungsten electrodes to join various metals. The tungsten electrode is a critical component in the process, as it channels the current required to establish the arc. The tungsten electrodes can be alloyed with a variety of metals. Different types and sizes of electrodes are used for different types of welds and materials, and welders develop preferences based on welding style and project. Certain electrode types perform better with alternating current (AC) as opposed to direct current (DC). Electrodes are shipped without a ground tip. If grinding a tip, make a tight, sharp point in order to achieve a powerful and precise arc to ensure a clean weld.tungsten electrodes are used when arc welding with the Tungsten Inert gas (TIG) process or when plasma welding. In both processes the electrode, arc and weld pool are protected from atmospheric contamination by an inert gas. A tungsten electrode is used because it can withstand very high temperatures with minimal melting or erosion. Electrodes are made by powder metallurgy and are formed to size after sintering.
TIG welding electrodes usually contain small quantities of other metallic oxides which can offer the following benefits:-
facilitate arc starting
increase arc stability
improve current-carrying capacity of the rod.
reduce the risk of weld contamination
increase electrode life