The Kenya Flourspar

The fluor (CaF2) puzzles were discoered by prof. Al Amin in 1967 in the aras of Kimw ber, Choff and Kamnaon. He was searching for semi-precious s t onenesss, and initially mistook the purple fluorspar for gemstone. He t here(predicate)fore collected the sample distri just nowion and took them for digest in Mombasa. It was later run aground to be fluorspar.A hand- archeological site ope symmetryn was started and the fluorspar was supplied to the Bamburi Portland cementumum Company in Mombasa. At its peak, the operation, which relied on donkeys to transport the fluorspar, produced around 400 wads per month of high grade fluorspar. In 1971 the fluorspar Company of Kenya (FCK) was established, under the evasive c everyplace of the Kenya government, to exploit the poses on a big scale. suppress and jigging plants were later put up at mining aim for Brobdingnagian scale merchandiseion of the metallurgical grade. Kenya fluorspar was a state parastatal upto 1996 when it was privatized.It is currently owned by local and foreign investors. The telephoner has seven active mining sites available from which ore preserve be mined depending on the grade and tonicity required. In 2003 the family leted made a major investiture in earth-moving equipment and plant upgrading. The postulate has been commercially mined since 1971. Initially, metallurgical grade fluorspar was produced. In 1975 a 100,000 ton per annum dit grade fluorspar concentrator was commissioned and by 1979 metallurgical grade fluorspar was no longer produced as primitive product, but can still be produced as secondary product for smaller consignments.The Kimwargonr ore deposit has now been mined for over 35 years It is an EPZ (Export litigateing zone). LOCATION Kenya fluorspar is a concern based in the Kerio Valley in the district of Eldoret and Iten. physical composition OF FLOURITE (CaF2) The fluorspar is an industrial mineral organize 150 to 200 linger aroundion ye ars ago. It is create by replacement reply known as mesomatism. The magma or acid wet containing fluorine and an opposite(prenominal) minerals was oblige up from deep within the Earth. When this saltwater reached the atomic number 20 rich, limestone bedrock (CaCO3), fluorite crystals formed along the walls of fractures and voids in the rock.Flat layers of fluorite as well as formed check to the limestone beds, replacing the soldiery rock. The fluorine replaced the CO32- from the CaCO3 to form CaF2. The CO32- was dissipated as CO2 and water. This cognitive operation is upgrade luxuriant in equation downstairs Ca2- + F22- CaF2 (fluorite) GEOLOGY AND OCURRENCE fluorite (also called fluorspar) is a halide mineral composed of calcium fluoride, CaF2. It is an isometrical mineral with a boxlike ha crisp, though octahedral and more complex isometric forms argon not uncommon. Crystal duplicate is common and adds complexity to the observed crystal.The fluorite deposits argo n believed to be of hydrothermal o gear upin in the Post-Miocene era when lavas formed a protective cap over Precambrian rocks in the atomic number 18a. The chief(prenominal) deposit of fluorite is located at Kimw atomic number 18r and is exposed on a serial worldation of five hills, four of which have been mined. 2 other minor deposits knows as Choff and Kamnaon be approximately 2 to 5 km north of the present mine site and have been partially mined in the past for the production of metallurgical-grade spar. The Kimw ber ore bodies contain by far the largest ore reserves. The ore frame contacts are straightforward due to the buff colour of the ore in contrast to he grey gneiss, blank marbles or pegmatites. Typically the fluorite is amercemently crystalline and disseminated through a siliceous matrix. Zones of high grade ore are frequently purplish or chromatic yellow in colour with cavities modify with distinct cubic crystals. The Choffs have devil ore bodies running pa rallel to each other for more than 3 km. The Choffs are conf apply by ridges and dips. The ore body pinches and swells and its width varies mingled with 4 metres and 26 metres. This ore is soft and crumbly hence easy liberation in the plant and provides a good yield. The phosphate in this vein is medium to high.The Kamnaon ore body has more than five partly parallel veins with varying dips of between 35-45 degrees. There are a number of other sites which are yet to be explored. The Fluorite at Kerio Valley occur as a vein deposit, especially associated with galena, sphalerite, barite, quartz, calcite and metallic minerals, where they often form part of the gangue (the surrounding host-rock in which valuable minerals occur). It is a common mineral in deposits of hydrothermal origin and has been noted as a primary mineral in granites and other igneous rocks and as a common minor constituent of dolostone and limestone.The deposit at Kerio Valley is steeply diping at 40o, with strike varying with mine mine Strike Percentage CaF2 No. of mines mines operating(a) Cheberen North-South 37% 1-6 1and3 Kamnaum North west-South east 40% 1-5 1 Choff East-West 50% 1-12 6and9 The deposit is distinguish from Kamnaum to Cheberen1. The fluorite is polychromous i. e occurs in diametric colours depending on the trace elements. The different colours allow * Colour little * chromatic * Green * Purple * Base yellow. GRADES OF FLOURSPAR The fluorite can be dish outed into grades depending on the use 1.Acid grade This grade is utilise in the manufacture of Hydrofluoric acid (HF). 2. metallurgic grade This grade is apply as flux in steel and cement industry. 3. Ceramic grade This grade is used in the manufacture of ceramics. Only the acid grade is currently produced by Kenya fluorspar. metallurgical grade was also produced but s cover versionped. major IMPURITIES AVAILABLE IN FLUORITE 1. silicon dioxide (silicon dioxide), SiO2 2. Calcite (calcium carbonate), CaCO3 3. the Tempter pentaoxide , P2O5 4. Iron(III)oxide, Fe2O3 STAGES IN MINING AND PROCESSIG OF FLOURITE (CaF2) 1. geographic expedition 2. Overburden remotion 3. Mining . treat EXPLORATION This is usually done to obtain sufficient information around the deposit in order to enable a safe and economic design and to forfend difficulties during mining of the fluorite. The Kenya Fluorspar utilizes the diamond warmheartedness commiting machine to obtain the class period cores. This machine can drill upto 140m-180m reconditeness. The drill cores are then(prenominal) logged upto beyond the fluorite zones. The drill cores are then taken to laboratory for testing. The cores undergo through assessment, finish and classification. Diamond core bore equipment. inflict CLEARING AND OVERBURDEN removalLAND CLEARING This involves the removal of all the trees and stumps including the roots from the mining site. In Kenya Fluorspar, currently land clearing and saddle removal is done at choff 9. T he master(prenominal) equipment used for land clearing at choff9 is a D355 Komatsu tractor-mounted dozer. The brush is disposed by toss in gullies. D355 dozer. OVERBURDEN REMOVAL This involves the removal waste soil or rock that overlies the ore. At Kenya Fluorspar the overburden depth depends on the denudation ratio and dipping angle. Dozer is the main equipment used for stripping the overburden at choff 9.This equipment pushes the overburden over the high wall. After the overburden has been unfinished by the dozer, it is plastered onto trucks by a hydraulic hoe excavator for dumping in gullies. The waste is then pushed into gullies by the D355 dozer. Overburden is outside at a ratio of 31 to 81 (waste to ore) depending on the ore body, with over 700,000 hemorrhoid of waste be stripped per annum at current production directs. Overburden is normally trucked away apply 25 ton trucks provided by contractors. Overburden stripping continues until the fluorite is exposed. ORE EXTRACTION (MINING) Mining is by open(a) cast methods.The exposed ore is extracted by cut and blasting. A total of approximately 360,000 tons of ore is mined annually. The geology has indicated that the ore body extends beneath the valley floor level and an open stigmatise is being planned. Drilling and blasting The Kenya Fluorspar utilizes two types of drilling equipment (rig) to drill holes. These complicate 1. Down the hole excogitate (DTH). This is generally used in solid lowering formations. The hammer is just behind the bit. 2. raising hammer drill rig (TH). This is generally used in loose formations. The hammer is on top of the drill draw and quarter (pipes).Crawler mounted DTHTop hammer drill rig The drill pattern to be apply depends on the 1. Size of the drill bit to be used. 2. Geological condition of the area. accomplishedly the bits are 102mm The drill pattern is square, 3m by 3m (burden by spacing) when there is a rid face and staggered in absence of a f ree face. The depth of the drill holes differs, with most holes 10m and others 7m and 4m. Subdrilling is normally 3m. Both the DTH and TH are crawler mounted with TH complete with compressor mounted on it. Kenya Fluorspar has 3 operating crawler mounted drilling machines (2 DTH and 1 TH).BLASTING This operation involves the pursual degrees 1. forwardness of ANFO 2. Hole charging 3. Initiation of volatiles PREPARATION OF ANFO This involves alloy the ammonium nit measure with fuel (diesel) in the ratio 0. 075ml of diesel for every 1kg of ammonium nitrate. This operation is done by an explosive mixer in Kenya Fluorspar. HOLE CHARGING This deal involves placing help/ primer at the bottomland of the drilled hole. The boosters normally used include cast booster, pentolite booster and gelignite. The Kenya fluorspar utilizes the pentolite booster for the priming purposes.Before placing the primer it is connected to a detonator. These detonators include 1. Plain detonators 2. Instanta neous electric automobile detonators. After placing the primer, ANFO is added depending on the hole depth as shown in the table downstairs Hole depth Height of ANFO Stemming 10m 7m 3m 7m 5. 5m 1. 5m 4m 3. 5m 0. 5m These holes aerated are then connected by 25MS (millisecond) nonel shock metro-shaped structures, short(p) period detonating check over (SPDD) type. The rows are connected by 17MS arise trunk lines (also nonel shock tubes). The nonel shock tube has the adjacent advantages 1.Produces low noise and quiver 2. It has less(prenominal) fly rock. It is because of the above advantages that fake it useful near factory where less vibration are required. The nonel shock tube is very expensive. INITIATION OF EXPLOSION at one time charging is complete the explosion can be initiated depending on the detonator used. Initiation can be done using the following 1. Safety fuse which burns at a rate of 2 transactions per metre. This is used case of plain detonators 2. blast machin e incase of electric detonators. tributary blasting is also done incase large boulders are produced in the primary blasting.Large boulders can also be worried using the rock breakers. LOADING AND attracter The blasted ore is loaded into trucks by an hydraulic excavator (Komatsu) hoe. The loaded ore is hauled a short distance of between 2 km and 7 km by promise trucks to the crushing plant. These trucks range from 10tons to 20tons. The ore stock pilled on an individual basis depending on the source. PROCESSING OF FLOURITE (CaF2) The processing of fluorite at the processing plant involves the following stages 1. portmanteau word 2. Crushing 3. Grinding 4. teach 5. Floatation 6. Thickening 7. filtration 8. Stock pillingBLENDING Blending in normally done at the primary crusher by a stray loader before presenting into the crusher in ratio of 2cheberen1choff1kamnaum This blending ratio ensures that the lead is 40% CaF2 CRUSHING Types of crushers 1. Primary crusher point out cru sher 2. Secondary crusher chamfer crusher 3. Tertiary crusher cone crusher PRIMARY CRUSHING The ore head for the hills to the grasshopper through a 12in grizzly screen. It is then feed to the primary crusher through an apron feeder and belt conveyor. The ore is first embarrassed in a primary stage crushing plant from a feed of 350 mm to less than 30mm in size.The ore that is less than 60mm but more than 30mm is passed through the cone crusher where it is further reduced to less than 30mm. whatever visible that is more than 30mm is passed through the 3rd crusher. GRINDINGTypes mills used in Kenya Fluorspar 1. Rod mill 2. Ball mill 3. Re-grind mill. It is then conveyed to the grinding circuit where the stuff is added to a rod mill along with water to form slurry. The rod mill instantly grinds the ore after which it is sized using a hydrocyclone. Any oversized material is passed to the ball mill for a further grinding to the desired size of 80%.The ore is now ready for condit ioning and flotation. CONDITIONINGThis process takes place in the conditioner. This where the depressants and stock batterys are added. 1. Depressants a) atomic number 11 fluorite which depresses the P2O5 b) Sodium bifluorite which also depresses the P2O5 2. Collectors a) Betacol b) TapiocaThis process renders the fluorite hydrophobic by the plus of a surfactant or collector chemical substance. flotationFlotation is the process that concentrates the ore. This is done by agitative the ore slurry in cells with air bubbles.By adding a cabal of fatty acid reagents, the fluorspar in the ore attaches itself to the air bubble to float to the top of the cell. This product is skimmed off sledding the waste in the bottom of the cell. The process is conducted in a series of rougher, scavenger, and antiseptic cells that successively concentrates the ore from 40% CaF2 in the feed material to a minimum of 97. 0% CaF2 in the final concentrate. The water in the final product is then removed in a thickener and a rotary drum drip. This produces a slabber stripe concentrate containing approximately 11. % moisture. The samples are analyzed in the companys assay and interrogation laboratory. The waste product is manage to the tailings dkm and settled water is re rolld to the plant for reuse. A FLOATATION CELL office CaF2 CONCENTRATED PER SERIES OF FLOATATION CELL FLOATATION CELL PERCENTAGE CaF2 CONCENTRATED ROUGHER CELLS 80% SCAVANGER CELLS 85%-87% spic-and-span CELLS 97% FLOATATION CIRCUITDEWATERINGThe water in the final product is then removed in a thickener and a rotary drum filter. This produces a filter stripe concentrate containing approximately 11. % moistureTHICKENER orbitual DRUM FILTEROperational Sequence * Cake composition With the overflow weir set to a level best the apparent submerging is normally 33-35% so the slurry levels between 0400 and 0800 hrs. erstwhile a arena enters submergence vacuum is utilise and a cake starts to form up to a poin t where the field emerges from the slurry. The pot of the cycle available for formation is the effective submergence and its duration depends on the number of sectors, the slurry level in the tank and the bridge aspect which take ins the form to dry ratio. Cake slipstream and Drying After emerging from submergence the drying deal out of the cycle commences and for non-wash applications continues to about 0130 hrs where the vacuum is cut-off. If cake washing is required the wash manifolds impart be located from about 1030 to 1130 hrs and the stay time to vacuum cut-off at 0130 is the portion allocated to final cake drying. * Cake justify After vacuum for the entire sector is cut-off air blow commences at about 0200 hrs in order to facilitate cake shake off.The blow, depending on the position of the tip of the scraper blade, bequeath cut-off at approximately 0300 hrs. Drum filters are normally operated with a low insistence blow but on plastered applications a snap blow is applied and to avoid the snapping out of the caulking bars or ropes wire winding of the cloth is recommended . swelling is used on scraper and roll dismiss mechanisms but on belt discharge filters vacuum cuts-off when the filter media leaves the drum. The final product has composition shown in the table below PRODUCT PERCENTAGE COMPOSITION Fluorite, CaF2 more than 97%Silica, SiO2 slight than 1% Carbonate, CaCO3 Less than 1% Iron III oxide, Fe2O3 Neglible Phosphorus penta oxide, P2O5 Less than 0. 5% TAILINGS DAMTailings, also called slimes, tails, despoil residue, or slickens, are the materials left over after the process of separating the valuable fluorite from the uneconomic fraction (gangue) of the ore. These are the wastes from the floatation cells. Tailings are distinct from overburden or waste rock, which are the materials overlying an ore or mineral body that are displaced during mining without being processed.The tailing are pumped from the processing plant to the to ta ilings dam for disposal. The top side is about 15m and dimensions are 150m by 30m. it is trapezoidal in shape. The dam also has poop out pipes to remove the seepage water. Hydraulic cyclones are used to build the dam. The cyclones separate the tailings into fine and coarse material. The coarse materiel from the cyclone underflow is used to build the wall of the dam volition the material and water is disposed into the dam. The water is recycled and pumped back for reuse into the factory. The pass on built until the dam touches the adjacent hill.LABORATORY tone CONTROLL SECTIONThe company conducts two types of tests chemical and metallurgical. The chemical scratch performs wet chemistry analytic thinking (mainly titration) and operates 24 hrs a day passim the year and each shift is headed by a qualified chemist. The metallurgical section mainly concentrates on research and breeding work. The sample (pellet) is subjected to an XRF machine which scans the sample impartation e nergy to it. The sample then radiates awaken of various wavelengths. The wavelengths are analyzed by a computer program which displays the information instantly on the screen.Strict quality control of run-of-mine ore, exploration and final product analysis is maintained by try. KFC prides itself in the quality of its assays, which are always crosschecked with those of European laboratories, viz. SGS (Netherlands), HOFF and BSI in the United States. Weight sampling and analysis All analyses are being performed by SGS Kenya Ltd (Swiss company) at the cost of the company. apparatus in the laboratory a) Two tattle crushers (14in. and12in. ) b) Pulverizer c) Oven for drying d) Splitter e) XRF machine f) Analytical correspondence g)A pilot plantSample preparation i. Drying ii. Splitting iii. Crushing iv. Pulverizing. CARGO CONDITIONThe fluorite is Chemically inert, non-reactive, non-flammable, non-hazardous mineral sand. No hazard labelling required in accordance with IMO regulation s. No special precautions for storage however, in order to maintain the honour of the material, it must not be allowed to be contaminated by any other material as it is used as the base product in natural chemical processes to produce other products and substances.TRANSPORT Once the acid spar is produced, the fluorspar is loaded into 10 ton trucks and hauled to the groomway side at Kaptagat, a distance of 37km. From here it is loaded into 36 ton rail wagons for the 860 km journey to the Mbaraki wharf at Mombasa. The wagons are offloaded at the wharf where the fluorspar is stockpiled and covered while awaiting shipment. The storage capacitance at Mbaraki is approximately 25,000 tons. The process of off-loading of wagons and trucks is lying-in intensive by means of manual(a) labour.Loading of the vessels is conducted using an automatic Demag Ship Loader, owned and operated by Bamburi Portland Cement Company. An average rate of 2,500 tons per day can be loaded on a unremitting basis even on public holidays. The quantity loaded and moisture analyses are conducted by an independent surveyor on a continuous basis to ensure a representative result of the product loaded. Since Mombasa is one of the main ports in East Africa, chartering of vessels to pass bulk cargoes to any destination in the world can be easy arranged.