mining cost for magnetite and haematite iron ore

eco-efficient and cost-effective process design for magnetite iron ore - metso outotec

It is very well known that energy production also implies emission of CO2, as shown in Figure 1 (www.ceecthefuture.org). The information indicates that almost 50% of the total CO2 emissions are generated by the comminution processes (crushing and grinding operations). For this reason, it is crucial to innovate through new technologies right from the conceptual phase to determine the best process route or circuit configuration.

Moreover, some countries are already imposing taxes on the emissions of greenhouse gases which is certain to have a negative effect on the process operating costs. Figure 1 shows the amount of CO2 emissions in each of the unit operations relating to mining operations and mineral processing.

The majority of steel production is supported by iron ore sourced from high-grade hematite deposits, although a significant fraction comes from magnetite deposits. Compared to direct shipping hematite ores mined from the upper regolith, magnetite deposits require significant beneficiation, which typically involves grinding to a particle size where magnetite is liberated from its silicate matrix. Many banded iron formation deposits are very fine grained, often requiring a final concentrate grind size P80 of 25-35 m (see liberation curve of magnetite in Figure 2). The amount of energy required to produce a magnetite product suitable for sale as pellet plant feed from these deposits is an order of magnitude higher than an equivalent direct shipping lump (< 32 mm > 6 mm) and fines (< 6 mm) hematite project.

The cost associated with high-capacity processing of a hard, fine-grained, silica-rich magnetite ore is presented in this paper, with the emphasis on comminution circuit options. The objective is to evaluate several options involving different grinding technologies with respect to energy consumption, operating cost and capital cost. Therefore, a typical conceptual or scoping level assessment methodology used by engineering companies was applied.

Historically, the lowest operating cost for fine-grained ores was achieved by multi-stage, fully autogenous grinding (Koivistoinen et al, 1989) with integrated magnetic separation steps between the stages. The major benefit of fully autogenous grinding is the elimination of steel grinding media costs and the need to discriminate between steel and magnetite in coarse magnetic separation ahead of pebble crushing. The separation step between grinding stages progressively reduces the amount of material to be ground and, in many cases, reduces the abrasive properties of the concentrate.

Some of the best known magnetite companies using autogenous milling are the subsidiaries of Cleveland-Cliffs Inc. in North America. The original autogenous milling circuit, consisting of an AG mill followed by cobber magnetic separation of pebbles, pebble milling of the magnetic concentrate, a finisher magnetic separation stage and silica flotation, was installed at Empire Mines in 1963 (Weiss, 1985). There have been three expansions since and, in the 1990s, Empire Mines had a total of 24 individual concentration lines and a total plant capacity of 8 Mtpa of pellets. The target grind size of the circuit varies between the 90-95 percent minus 500 mesh (32 m) depending on the ore and operating conditions (Rajala et al., 2007). For this specific case, Figure 2 shows the liberation curve for the magnetite ore.

Significant reductions in the costs associated with grinding were achieved over the first 80-90 years of the last century by increasing the size and improving the design of the crushers and mills; however, there was no major breakthrough in improving the energy efficiency of the comminution process.

Only in the last 20 years were the more energy-efficient technologies successfully implemented at an industrial scale, including high-pressure grinding rolls (HPGR) for fine crushing (Dunne, 2006) and stirred milling for fine grinding (Gao et al., 2003). The application of more efficient grinding technologies has provided opportunities to further reduce the operating costs associated with grinding. At Empire Mines, an HPGR was installed for processing crushed pebbles, and its introduction resulted in a primary AG mill throughput increase of the order of 20 percent (Dowling et al., 2001). The application of Vertimill fine grinding technology at Hibbing Taconite Company enabled processing of lower grade ores and increased the concentrate production (Pforr, 2001).

A sharp increase in the application of HPGR and stirred mill technologies is recorded in the last decade, driven by the benefits of increased energy efficiency and supported by improvements in equipment reliability. The potential for the reduction of energy consumption of the order of 30-45 percent was suggested to be possible (Valery and Jankovic, 2002), although significantly lower reductions, 9-13 percent, were reported after detailed engineering studies for two large copper projects (Seidel et al. 2006). This clearly indicates that benefits from new energy-efficient technologies are case specific and the intention of this paper is to show the potential for the magnetite ore processing.

A study into the options for a 10 Mtpa ore processing plant for a hard, fine-grained, silica-rich magnetite ore was carried out, with the emphasis on comminution circuit options. The concentrator was assumed to be located within 100 km of a port suitable for facilitating equipment delivery. It was assumed that there were no restrictions on spatial layout and that the process facility would be built on ground of a sound geotechnical character. Any subsequent differences in tailings disposal, water recovery and their associated operating requirements and costs were not considered.

The fine-grained nature of this hypothetical ore results in a relatively late release liberation curve. This fundamental property of a magnetite ore is generally one of the major drivers of flowsheet design and, therefore, flowsheet option generation.

COS coarse ore stockpile; SC secondary crush; HPGR high-pressure grinding roll; AGC autogenous mill in closed circuit with cyclones and pebble crusher; RMS rougher magnetic separation; CMS cleaner magnetic separation; CMS2 - second cleaner magnetic separation; PM pebble mill; PC primary crusher; SM stirred mill; and TSF tailings storage facility.

Option 1 resembles the well-known fully autogenous LKAB and Cleveland Cliffs style, low operating cost operations. The absence of steel grinding media is the major basis for the low operating cost. Pebble mill control and pebble transport and handling requirements add complexity to the design and operation.

Primary crushing AG milling in closed circuit with hydrocyclones and pebble crushing rougher magnetic separation ball milling cleaner magnetic separation tertiary milling using stirred mills second cleaner magnetic separation.

Option 2 has an additional grinding and magnetic separation stage compared to Option 1 and is considered to be simple for design and operation. The final milling stage is carried out using energy-efficient stirred mills. Steel grinding media usage significantly increases the operating cost.

Primary crushing closed circuit secondary crushing closed circuit HPGR rougher magnetic separation ball milling first cleaner magnetic separation tertiary milling using stirred mills second cleaner magnetic separation.

In Option 3, secondary crushing and HPGR effectively replace AG milling with pebble crushing. The application of HPGR, stirred milling and an additional magnetic separation stage reduces the power requirements compared to Options 1 and 2.

Primary crushing secondary crushing screening Open HPGR coarse pebble milling rougher magnetic separation fine pebble milling first cleaner magnetic separation tertiary milling using autogenous stirred mills second cleaner magnetic separation.

Option 4 is an attempt to design a circuit with the lowest operating cost through increased grinding energy efficiency using three stages of magnetic separation, traditional autogenous milling, HPGR and stirred milling technology. In this conceptual flowsheet, steel grinding media is eliminated. Circuit complexity is partially reduced by open secondary crushing, HPGR grinding and stirred milling operation, although recovery, storage and control of three separate-sized media streams are introduced.

With the exception of the primary crushing module, which is consistent between options, estimates were developed for the total power drawn in the comminution, classification and magnetic separation areas of each circuit. Energy consumed by material transport machinery related to pumping between areas was not considered at this level of the study. A summary of the comparison of unit circuit energy for each option is shown in Figure 3.

A significant energy reduction is predicted for Options 3 and 4, which include HPGR and stirred milling. Some 33 percent of additional energy separates the most energy-efficient option (Option 4) from the least efficient, the two-stage AGC Pebble circuit (Option 1). Note that part of the energy reduction is also due to the fact that the process uses unit operations that are better suited to each stage of grinding, i.e. stirred mills are much for efficient for fine grinding than tumbling mills. It can also be attributed to the fact that Options 3 and 4 have an additional separation step at a coarse grind, which reduces the amount of material for fine grinding.

According to Seidel et al. (2006), the basic comminution energy requirement for the Boddington HPGR circuit option was 14 percent lower than the SAG option; however, the overall energy requirement, including conveying, screening etc, was reduced to 9 percent. The Boddington copper gold ore is of similar rock competency to that selected for this study and thus provides a good contrast between comminution processes designed to liberate minerals for flotation, in which the whole ore is ground to fine size, and the comminution process with the staged rejection of silicates. In the latter case, the energy consumption difference between flowsheet options can be significantly higher.

A fairly detailed approach was taken in terms of the development of operating costs for each option. Consumption rates for power, wear and other consumables were considered for each process flowsheet. Maintenance and materials, as well as labor, were also considered. The scope covered included the process from the COS reclaim feeders to either the final magnetic separator concentrate discharge or the magnetic separator tailings discharge. As such, no concentrate or tailings handling, filtration or storage costs were considered. For simplicity, some minor operating costs, such as metallurgical testwork and analysis, which is considered common to all options, have been omitted.

Unit costs for power, grinding media, wear consumables and labor were referenced from average values within the GRD Minproc database for similar-sized and located projects. A factoring approach from the direct capital cost was used to develop cost estimates for maintenance materials. Key assumptions are listed in Table 2. All costs are estimated in Australian dollars and are presented as 1st quarter 2009 costs.

A carbon tax is expected to be introduced in the near future and would add a significant cost to all operations. For this exercise, a simplified estimate of the effect of a carbon tax is considered. It was assumed that the carbon tax would be applied to total circuit energy and steel consumption relating to media and comminution equipment wear liners. The following criteria were applied for the carbon tax estimate: CO2 emission, 5 t per 1 t of steel media (Price et al, 2002), CO2 emission, 1.0 kg per kWh of electricity, CO2 tax, $23 per t of CO2 (Australian Government, 2008).

The most significant operating cost (OPEX) variables between options are those relating to power, media and liner consumption. The two options including AG mill circuits have between 27 and 32 percent higher power consumption costs relative to Option 4, which utilizes the more energy-efficient autogenous grinding technologies.

Grinding media and wear lining costs range between 0.41 $/t and 1.82 $/t. Option 3 has much higher media and wear lining costs because two ball mills of 8.8 MW installed power each are required to grind 8 Mtpa of RMS concentrate from P80 2.3 mm to P80 75 m. The overall OPEX for Option 3 is the highest due to the high costs of media and liner wear.

Table 3 shows a summary of calculations related to the carbon emission and carbon tax effect on OPEX. It can be observed that the introduction of carbon tax at 23 $/t would increase OPEX to the order of 9-11 percent. The majority of carbon emission is from electrical energy consumption, while the indirect contribution from steel consumption is dominated by grinding media and is of the order of 5-16 percent for the options that utilize ball milling (Option 2 and 3).

The CAPEX estimate is developed based on the premise that the process is located inland in West Australia. All costs are estimated in Australian dollars and are presented as 1st quarter 2009 costs. They are estimated to have an accuracy of 35%, which is commensurate with the accuracy requirements for a high-level options study of this nature. The details of the cost estimate can be found in McNab et all, 2009. The total capital cost was as follows:

The total estimated CAPEX for each circuit is within 14 percent, which infers that none of the options is a standout from a capital cost perspective at the accuracy level for this study. In comparison, the Boddington copper gold project CAPEX (Seidel et al. 2006) for the HPGR circuit option was 7 percent higher than the SAG option. Therefore, it appears that there may not be any significant CAPEX penalty for the adoption of more energy-efficient grinding technologies when considering magnetite ore processing.

High-level, pre-tax, net present value (NPV) determinations were calculated for Options 1 to 3 relative to the base case, Option 4 by applying a 10-percent discount rate over 12 years of operation. Option 4 was used as the base case since it returned the lowest capital and operating cost, and therefore NPV. Options 1 and 3 have a similar NPV outcome ranging between negative $94-95 M relative to Option 4. Option 2 shows the least favorable outcome with a $118 M NPV deficit relative to Option 4. This option has the combined disadvantages of both high capital and operating costs. The conclusion drawn from this financial evaluation is that highly energy-efficient autogenous processing routes can offer significant financial advantages for competent magnetite ores requiring fine grinding.

The traditional AG mill and pebble mill-style comminution circuit or those requiring significant steel grinding media to operate have been found to be less effective from a purely economic perspective. Circuit options utilizing multi-stage magnetic separation and with energy-efficient autogenous comminution equipment, although more complex, are more likely to add project value. For the ore type evaluated, the application of HPGR and stirred mill technology is indicated to reduce energy consumption by up to 25 percent compared with conventional flowsheets with wet tumbling mills.

There are many other flowsheet selection drivers that can become relevant, however, the operating cost associated with power draw and grinding media will always remain critical, even more so with the expected introduction of a carbon tax. A synergy of HPGR, pebble and stirred milling can result in a very effective circuit from a capital and operating point of view. It can be expected that highly energy-efficient autogenous processing routes would be further developed and increasingly applied in practice.

types of iron ore: hematite vs. magnetite_smm | shanghai non ferrous metals

Iron ore consists of rocks and minerals from which iron can be extracted. Ore is most often found in the form of hematite and magnetite, though goethite, limonite and siderite types are also common. Approximately 98 percent of the iron ore produced in the world is used to make steel.

Hematite ore has the chemical formula Fe2O3 and has a very high iron content of 70 percent. Its name comes from the Greek word for blood, haima, because of its reddish color. High-grade hematite ore is also often referred to as direct shipping ore because it is mined and extracted with a fairly simple crushing and screening process before it is exported. Hematite can be found in abundance throughout the world, but the most utilized deposits are in Brazil, Australia and Asia.

Hematite has been the primary type of ore mined in Australia since the early 1960s, according to Geoscience Australia. Approximately 96 percent of the continents iron ore exports are high-grade hematite, and the majority of the reserves are located in the Hamersley province of Western Australia. The mountainous Hamersley Range is at the center of hematite exploration and development because it sits on a banded iron formation.

Brazil is another one of the worlds main sources of hematite ore. Its Carajas mine is the largest iron ore mine in existence and is operated by Brazilian mining company Vale (NYSE:VALE). Vale is the second-largest mining company in the world and the largest private sector firm in Latin America. Vales headquarters are in Rio de Janeiro and its primary iron ore assets are in the Iron Quadrangle region of Minas Gerais, according to its website. This area has eight projects, all of which are open-pit mines.

One of the major advantages hematite ore has over other types like magnetite is its high iron content. That makes the iron extraction process much less costly and time consuming. In addition, hematite ore only goes through one stage of screening and crushing, while magnetite has an additional round of processing.

With the chemical formula Fe3O4, magnetite ore has much lower iron content than hematite ore. That means it has to be concentrated before it can be used to produce steel. However, the ores magnetic properties help separate magnetite from rock during concentration.

Magnetite ore is currently mined in Minnesota and Michigan in the United States as well as in taconite deposits in Eastern Canada. A major mining site in Michigan is the Marquette iron range. The deposit was discovered in 1844 and ore was first mined there in 1848, as per the State of Michigans website. Among the four types of iron ore deposits found in this area are magnetite and hematite ore.

In Minnesota, magnetite iron ore is mined mainly in the Mesabi iron range, one of the four ranges that make up the Iron Range of Minnesota. In Canada, Labrador is home to the majority of magnetite mining. In particular, mining companies focus exploration and development on the iron-rich Labrador Trough.

Magnetite ores most distinctive property is its magnetism. It is the most magnetic mineral in the world. Additionally, obtaining iron from hematite ore can produce a great deal of carbon emissions, and the process for magnetite is much less harmful.

The product from magnetite ore is also of higher quality than from hematite ore. The former has less impurities, making it a premium product that can be sold to steel makers for higher prices. In this way, the elevated cost of processing magnetite ore can be balanced out.

Cliffs Natural Resources (NYSE:CLF) is a major player in the magnetite mining industry. It is the largest producer of iron ore in North America, according to the Minnesota state government. These include six mines that are focused on magnetite ore. For instance, the Empire Mine, located in Michigans Marquette Iron Range, has a rated annual capacity of 5.5 million tons. Additionally, its Hibbing taconite mine is in Minnesotas Mesabi iron range and has an annual rate capacity of 8 million tons of magnetite ore.

The company operates three iron ore mines in Minnesota, which combined have the capacity to produce 18.2 million tons of iron ore pellets per year. Cliffs Natural Resources also owns an iron ore mining complex in Western Australia.

an account of magnetite ore in india | steel360 news

Indias Iron ore resources are estimated at 28.5 billion tonnes, distributed between Haematite at 17.9 and Magnetite at 10.6 billion tonnes. Though, both numbers are impressive at first glance; heres a staggering fact: while 45% of the haematite resources are classified as reserves, a meager 0.2% of magnetite receives the same recognition. This peculiarity inspired this article which elucidates magnetite and its role in the steel industry.

Magnetite is a black/brownish black, naturally occurring iron oxide, represented chemically as Fe3O4. It is magnetic in nature hence the name a property that has been applied extensively while dealing with the mineral. Being a source of iron, it is the starting material for many iron & steel producers around the world. Another application of magnetite, which should be of interest to this industry, is its use as a heavy media in coal washeries, to separate out higher grades of coal from lower ones. However, other materials may also be used for this purpose.

In a world perspective, magnetite has greater importance in several countries compared to India. China, the worlds largest steel producer, uses magnetite as the major raw material. Taconite, the principle iron ore in America, contains magnetite as the iron bearing material.Appreciable deposits are found in Australia and many European countries, especially Sweden. Other small deposits may be found across countries around the world.

In India, over 90% of magnetite is found in the southern states of Karnataka (73%), Andhra Pradesh (14%) and Tamil Nadu (5%). Rajasthan in the west accounts for another 5%. The balance is scattered over Goa, Kerela, Maharashtra, Odisha, Jharkhand, Assam, Nagaland & Meghalaya.

Like haematite, magnetite is not found in such high grades so as to be used as DSO. The ore is beneficiated for magnetite recovery. Magnetite ores have mere 15-40% iron content and as such, cannot be used directly for iron making. It has to be beneficiated to concentrate the iron bearing material. For this purpose, the magnetic nature of the mineral is employed. The entire process involves the crushing and grinding of ores to powder form, exposing it to a magnet for separation followed by other agglomeration processes for value addition and onward utilization. Most miners of magnetite ore install a beneficiation and Pelletisation line at the mining site for direct sales as feeding material.

A lot of Power is used up in the beneficiation process of magnetite, representing the bulk of the costing. Continuous research aims at reducing this factor, which would allow overall costs of using magnetite to come down, thus making it more competitive.

An obvious question here is why anyone would explore magnetite ores as it is of extremely low grade and involves high costs of beneficiation. However, magnetite attracts premium rates in comparison to its peer haematite because post-beneficiation, it has a high & consistent iron content concentration of 68% and a low associated gangue. On the other hand, the iron content of high grade haematite may vary between 60-65%. This rewards the buyer during steelmaking in the form of lower energy and carbon consumption, which more than compensates for the extra costing. Also, magnetite is used for high cleanliness steel as it has practically no P or S associated with it. Thus, it should not be surprising to know that magnetite is often tagged as the superior ore.

Magnetite during the firing stage of Pelletisation is oxidized into haematite. Here, it is essential to understand that both, magnetite and haematite, are oxides of iron, the latter containing more oxygen for each unit of Fe (higher oxidation state). In the first instance, this fact would prompt you to try and avoid haematite formation to the maximum possible extent, so as to deter association of more oxygen, which have to only be consequently removed during iron-making in a blast furnace or a DRI furnace/kiln. However, the oxidation during Pelletisation is imperative for the ores further use. A metallurgical explanation is the higher reducibility of haematite compared to magnetite. All factors remaining constant, the amount of reduction haematite would undergo is significantly greater than that of magnetite. In other words, haematite forms iron much faster than magnetite.

Another advantage of magnetite pelletisation is that it does not require any fuel to be added to the powder mix. Usually, coal fines, grinded petro coke, coke oven fines etc are part (around 1%) of the pellet mix so as to ensure homogeneous hardening of pellet during firing. But magnetite upon oxidation to haematite releases considerable energy which eliminates the requirement of an external fuel. As a leading steel producer in the country put it, we as an integrated steel plant utilize the coke fines generated in our ovens and during storage, in our pellet plant. However, if magnetite were to be available, the stand alone pellet plants, mainly the ones using Chinese technology & equipment, would be the most benefitted as they would then not be forced to raise temperatures and would prevent the oft encountered breakdowns. In the middle-east, plants use a mix of haematite fines and magnetite (30-35%) for pellet making in order to exploit this advantage, whilst also obtaining higher quality pellets.

The huge amount of magnetite present in India has already been stated in the introduction. However, after speaking to most major steel producers in the country, it can be safely claimed that none of them mine or purchase magnetite for their production. The major reason is the abundant availability of haematite in India, which can be used as a direct feed. The plentiful haematite aside, another reason for absence of magnetite in the Indian scenario is that even regional distribution does not warrant its use. The south, which holds most of the magnetite, is also blessed with sufficient haematite in Karnataka and Goa.

Though magnetite has no presence on the Indian scene today, the same hasnt always been the case. KIOCL Ltd had been allotted mines in Kudremukh, Karnataka and mined magnetite ore from here for 25 years, with a Pelletisation facility at Mangalore, around 100 kms from the mines. But, following a Supreme Court of India verdict in 2005, which stated that the mines were part of a National Park, KIOCL was banned from mining at Kudremukh. This was a setback for the thriving company. At the time, most had written off KIOCL as a thing of the past. However, the turnaround of the company, its adaptation of its beneficiation & pelletisation facility to suit haematite ore and its current success and growth is a corporate wonder.

Many say the use of magnetite is inevitable; if not today, then maybe years, surely decades later when the DSO grade haematite has been exhausted. Barring the high cost of beneficiation, magnetite scores over haematite on prime factors such as iron content and impurity levels and that beneficiated magnetite is superior to haematite is an established fact.

But, also of concern is the distribution of magnetite in the country. The largest concentration, in Karnataka, is mostly in a region which is ecologically sensitive. The Western Ghats, considered a biodiversity hotspot and identified as a World Heritage Site, is an important location in efforts of conservation and sustenance of environment. Also, ban on industrial activity here & there in the region is recurring news. It is for the future to unfold how the balance between nature and industry is struck.

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types of iron ore: hematite vs. magnetite | inn

For investors interested in the iron ore space, its useful to know the facts about hematite and magnetite ores. Both of those types of iron ore are rocks and minerals from which iron can be extracted. Heres an overview of some basic information about hematite and magnetite ores, including what they are and where theyre found.

Hematite ore is a direct-shipping ore with naturally high iron content. Because of its high iron content, hematite ore must undergo only a simple crushing, screening and blending process before being shipped off for steel production.

For that reason, hematite ore is important for many mining companies. As Australias Magnetite Network explains, [d]irect shipping ores, when mined, typically have iron (Fe) content of between 56% Fe and 64% Fe By comparison, magnetite ore typically has a much lower iron content when mined of between 25% and 40% Fe and in this form is unsuitable for steel making.

Hematite ore is found throughout the world, but the most utilized deposits are in Brazil, Australia and Asia. Hematite ore has been the primary type of iron ore mined in Australia since the early 1960s.

Approximately 96 percent of the continents iron ore exports are high-grade hematite ore, and the majority of its reserves are located in the Hamersley province of Western Australia. The mountainous Hamersley Range is at the center of hematite ore exploration and development because it sits on a banded iron formation.

Brazil is another one of the worlds main sources of this type of iron ore. Its Carajas mine is the largest iron ore mine in existence, and is operated by Brazilian miner Vale (NYSE:VALE). Vale is the third-largest mining company in the world and the largest producer of iron ore pellets. Vales headquarters are in Rio de Janeiro, and its primary iron ore assets are in the Iron Quadrangle region of Minas Gerais.

The mineral magnetite actually has higher iron content than the mineral hematite. However, while hematite ore generally contains large concentrations of hematite, magnetite ore generally holds low concentrations of magnetite. As a result, this type of iron ore ore must be concentrated before it can be used to produce steel. Magnetite ores magnetic properties are helpful during this process.

While magnetite ore requires more treatment, end products made from magnetite ore are typically of higher quality than those made from hematite ore. Thats because magnetite ore has fewer impurities than hematite ore; in this way, the elevated cost of processing magnetite ore can be balanced out.

Magnetite ore is currently mined in Minnesota and Michigan in the US, as well as in taconite deposits in Eastern Canada. A major mining site in Michigan is the Marquette Range. The deposit was discovered in 1844, and ore was first mined there in 1848. Magnetite ore and hematite ore are among the four types of iron ore deposits found in this area.

In Minnesota, this type of iron ore is mined mainly in the Mesabi Range, one of the four ranges that make up the Iron Range of Minnesota. In Canada, Labrador is home to the majority of magnetite ore mining. In particular, mining companies focus on exploration and development in the iron-rich Labrador Trough.

Cleveland-Cliffs (NYSE:CLF) is a major player in the magnetite ore industry, with five iron ore mines that are focused on magnetite ore. For instance, the Empire mine, located in Michigans Marquette Range, has an annual capacity of 4.5 million tons. Additionally, its Hibbing taconite mine is in Minnesotas Mesabi Range and has an annual capacity of 8 million tons of magnetite ore.

Now that you know a bit more about the different types of iron ore, would you like to know what the worlds top iron ore producers are? Click here to read about the 10 largest iron-producing countries.

Please remember that by requesting an investor kit, you are giving permission for those companies to contact you using whatever contact information you provide. If you want more than 20 investor kits, you need to make multiple requests. Select 20, complete the request and then select again.

In Canada, there are financial incentives to extract magnetite from mine tailings for export. Whitehorse Yukon has a rich magnetite deposit of this type with interest to see partner or buyer getting to the steel mills.

The two ores of iron are hematite and magnetite with the chemical formula Fe2O3 and Fe3O4 respectively. To determine which of the compounds has a higher percentage of iron per kilogram first the molar mass of the two compounds has to be determined. Iron has a molar mass of 55.845 g/mole and oxygen has a molar mass of 16 g/mole. The molar mass of Fe2O3 is 159.69 and that of Fe3O4 is 231.535. In hematite the percentage of iron by mass is `111.69/159.69 ~~ 69.9%` , similarly in magnetite the percentage of iron by mass is approximately 72.3% Magnetite has a higher percentage of iron per kilogram as compared to hematite.

The two ores of iron are hematite and magnetite with the chemical formula Fe2O3 and Fe3O4 respectively. To determine which of the compounds has a higher percentage of iron per kilogram first the molar mass of the two compounds has to be determined. Iron has a molar mass of 55.845 g/mole and oxygen has a molar mass of 16 g/mole. The molar mass of Fe2O3 is 159.69 and that of Fe3O4 is 231.535. In hematite the percentage of iron by mass is `111.69/159.69 ~~ 69.9%` , similarly in magnetite the percentage of iron by mass is approximately 72.3% Magnetite has a higher percentage of iron per kilogram as compared to hematite.

Iron ore pellets are made from both magnetite and hematite ores. Hematite ores are concentrated using a flotation process. Pellets include a mineral binder that represents about 2% by weight. Much of the ore in pellets made from magnetite is oxidized to hematite during the high-temperature induration process that sets the binder. Induration is necessary to instill the durability necessary to support a blast furnace burden, and to mitigate fines generation during shipping & handling. Direct shipping lumpy ore is now very scarce. Fine iron ore must be agglomerated before being fed to a blast furnace either by pelletizing or sintering, which is normally done at the steel mill. Fine iron ore cannot be fed to a blast furnace, or it will plug. The burden b=must be sufficiently porous to allow the wind to penetrate the birden. Sintering also provides a means to recycle steel mill wastes, including pellet chips, pit scrap and BOF dust.

Iron ore pellets are made from both magnetite and hematite ores. Hematite ores are concentrated using a flotation process. Pellets include a mineral binder that represents about 2% by weight. Much of the ore in pellets made from magnetite is oxidized to hematite during the high-temperature induration process that sets the binder. Induration is necessary to instill the durability necessary to support a blast furnace burden, and to mitigate fines generation during shipping & handling. Direct shipping lumpy ore is now very scarce. Fine iron ore must be agglomerated before being fed to a blast furnace either by pelletizing or sintering, which is normally done at the steel mill. Fine iron ore cannot be fed to a blast furnace, or it will plug. The burden b=must be sufficiently porous to allow the wind to penetrate the birden. Sintering also provides a means to recycle steel mill wastes, including pellet chips, pit scrap and BOF dust.

Atomic weights of Fe at 56 and oxygen at 16. In chemically pure minerals the percentage Fe in hematite Fe2O3 is 112/(112+48)=70%. Percentage Fe in magnetite Fe3O4 is 168/(168+64)=72.4%. In nature magnetite often contains impurities in the ore which makes the Fe content of mined ore lower than hematite. As stated the impurities in magnetite can be removed via processing often resulting in an Fe percentage higher than hematite.

Atomic weights of Fe at 56 and oxygen at 16. In chemically pure minerals the percentage Fe in hematite Fe2O3 is 112/(112+48)=70%. Percentage Fe in magnetite Fe3O4 is 168/(168+64)=72.4%. In nature magnetite often contains impurities in the ore which makes the Fe content of mined ore lower than hematite. As stated the impurities in magnetite can be removed via processing often resulting in an Fe percentage higher than hematite.

Hematite ore has the chemical formula Fe2O3 and has a very high iron content of 70 percent. With the chemical formula Fe3O4, magnetite ore has much lower iron content than hematite ore. No matter how I count it, Fe2/Fe2O3 comes as lower a mass fraction than Fe3/Fe3O4. So the statements above make little sense to me.

Hematite ore has the chemical formula Fe2O3 and has a very high iron content of 70 percent. With the chemical formula Fe3O4, magnetite ore has much lower iron content than hematite ore. No matter how I count it, Fe2/Fe2O3 comes as lower a mass fraction than Fe3/Fe3O4. So the statements above make little sense to me.

If I remember my chemistry, %Fe in (pure) magnetite is 70% and is actually higher than the %Fe in (pure) haematite which is 67.5%. So the opening line in the section on magnetite above is perhaps misleading since it is not the chemical composition which is the difference. The difference is the level of impurities in magnetite deposits which are removed by magnetic seperation and then pelletising is needed to agglomerate the fine magnetite material. This gives a pellet which is more expensive than high grade haematites but with a higher %Fe as the author then correctly states.

Hematite Fe2O3 2/3 =66%, Magnetite Fe3O4 3/4 = 73%max so Magnetite is higher content Fe and lessor contamination content. Fe2O3 can be turned into Fe3O4 with heat to drive out contamination and convert molecular structure. Natural Magnetite is much better for iron production. This artical has everything backwards. Back to basic chemistry

Hi there, thanks for commenting, and apologies for the error. You are, of course, correct magnetite does have a higher iron content than Hematite. However, I believe the original offer failed to make the distinction between hematite and hematite ores (the same goes for magnetite). Hematite can occur in high-grade ores, referred to as direct-shipping ores, which have higher iron content than naturally occurring magnetite ores. Still, as you note and as the article states, iron produced from magnetite makes for a higher quality end-product.

If I remember my chemistry, %Fe in (pure) magnetite is 70% and is actually higher than the %Fe in (pure) haematite which is 67.5%. So the opening line in the section on magnetite above is perhaps misleading since it is not the chemical composition which is the difference. The difference is the level of impurities in magnetite deposits which are removed by magnetic seperation and then pelletising is needed to agglomerate the fine magnetite material. This gives a pellet which is more expensive than high grade haematites but with a higher %Fe as the author then correctly states.

Hematite Fe2O3 2/3 =66%, Magnetite Fe3O4 3/4 = 73%max so Magnetite is higher content Fe and lessor contamination content. Fe2O3 can be turned into Fe3O4 with heat to drive out contamination and convert molecular structure. Natural Magnetite is much better for iron production. This artical has everything backwards. Back to basic chemistry

Hi there, thanks for commenting, and apologies for the error. You are, of course, correct magnetite does have a higher iron content than Hematite. However, I believe the original offer failed to make the distinction between hematite and hematite ores (the same goes for magnetite). Hematite can occur in high-grade ores, referred to as direct-shipping ores, which have higher iron content than naturally occurring magnetite ores. Still, as you note and as the article states, iron produced from magnetite makes for a higher quality end-product.

Thanks for both comments. Mr. Newell, regarding hematite vs. magnetite and their greenhouse gas emissions, I refer you to The Magnetite Network. Admittedly this is a group representing Western Australias magnetite producers. According to an independent report posted on the groups website, Mining and beneficiation of magnetite ore is considerably more energy intensive than conventional direct shipping hematite operations in the Pilbara. As a consequence, magnetite concentrate production is more CO2 emissions intensive than direct shipping ore (DSO ) production. (so you are correct there). But when entire life cycle emissions are considered (ground to steel), magnetite comes ahead of hematite, with a net savings of 108 kg CO2e per tonne of magnetite concentrate, as per the report. This is because emissions can be saved in overseas ironmaking operations- again, according to the report. If you find evidence to the contrary I would take a look at it. Best Regards, Andrew Topf, INN Senior Editor

Thanks for both comments. Mr. Newell, regarding hematite vs. magnetite and their greenhouse gas emissions, I refer you to The Magnetite Network. Admittedly this is a group representing Western Australias magnetite producers. According to an independent report posted on the groups website, Mining and beneficiation of magnetite ore is considerably more energy intensive than conventional direct shipping hematite operations in the Pilbara. As a consequence, magnetite concentrate production is more CO2 emissions intensive than direct shipping ore (DSO ) production. (so you are correct there). But when entire life cycle emissions are considered (ground to steel), magnetite comes ahead of hematite, with a net savings of 108 kg CO2e per tonne of magnetite concentrate, as per the report. This is because emissions can be saved in overseas ironmaking operations- again, according to the report. If you find evidence to the contrary I would take a look at it. Best Regards, Andrew Topf, INN Senior Editor

marampa haematite iron ore mine - mining technology | mining news and views updated daily

The Marampa mine is a brownfield haematite iron ore mine located approximately 150km north-east of Freetown in Sierra Leone, West Africa. 100% owned by London Mining, the project includes a 319km exploration licence that borders the Marampa mining lease, which was mined extensively between 1933 and 1975 by the Development Corporation of Sierra Leone (DELCO). The property was acquired by London Mining in 2006.

Full development of the project began on 11 February 2010 on receiving final parliamentary approval. The project will also include an $80m tailings reprocessing development operation that is expected to result in an output of 1.5Mtpa by 2011. The $85m operation will be expanded in a phased manner to 3Mtpa before production from the primary resource begins. Primary resource mining will increase production to between 5Mtpa and 8Mtpa upon completion of the project, by the end of 2013. Decision on the expansion remains pending in a pre-feasibility study that is scheduled for completion by the end of 2010.

The development will initially be fast tracked into production before expanding to a larger scale, thereby achieving short-term cashflow. The mine has historically operated at a peak production of 2.5Mtpa before it was suspended owing to low iron ore prices in the 1960s.

The Marampa mining lease combines two main ore deposits at the Masoboin hill and the Ghafal hill besides tailing deposits from earlier operation that cover low ground directly east of the Masaboin hill. Ten tailings deposits account for 85% of the estimated tailings tonnage and five peripheral deposits account for the balance.

The primary ore bodies within the deposit consist of 122.8Mt inferred resources graded at 31.19% Fe. The tailings portion of the mine contains an estimated 42.5Mt of indicated resources graded at 21.67% Fe.

The deposit lies within the Marampa Schist formation, a pre-Cambrian aged complex structure that hosts one primary quartz haematite schist horizon. The horizon that ranges in thickness up to 65m is isoclinally folded and thrusted, plunges east southeast at 45 to 85 and has steep contact with its quartz mica schist host rock. At least four stages of deformation have occurred at the schist. Iron oxide minerals formed due to prograde metamorphism include specularite-haematite (up to 60 modal%) and subordinate magnetite (usually less than 2-3 modal%). The schist hosts ultramafic and mafic units but does not include any detrital zircons of the Archaean period.

The tailings resource will be extracted using conventional techniques including the truck and shovel method and hydraulic mining. A two-phase high intensity magnetic separation process will result in 65.5% iron with 2.5% SiO2 and 2.9% Al2O3 from approximately 3t of tailings. A milling circuit, if included, will produce higher-grade 67.1% iron with 1.2% SiO2 and 2.1% Al2O3. This option is however currently not being considered as the demand for lower-grade Marampa products is higher in the region.

The concentrate will be hauled to barge-loading facilities located at Tawfayim on Loko Creek, 40km from the mine site. It will be shipped from there to floating cranes, 60km offshore for loading at a place that accommodates Handymax, Panamax and Capesize ships.

Exploration activities at the mine have identified a number of iron ore prospects. These include outliers and extensions of the same formation that hosted the iron mined during operations by DECLO. A significant amount of iron ore tailings on the mine area that were remnants of DELCO operations have also been identified.

By the end of 2009, London Mining had drilled 2,700m on the primary ore deposits. It plans to complete a further 6,000m of drilling in 2010. Successful completion of the drilling programme will allow the company to obtain a JORC-compliant estimate for the main ore resource besides completing the pre-feasibility study.