Introduction to Hainan Iron Ore Products Author：8866 Published：2014-09-02  Sources：Hainan Mining Investment  Views：0

 Hainan ore is hematite (Fe2O3) that contains high silicon, low aluminum, and low phosphorus. It is acid ore. Most imported ores contain low silicon and high aluminum. Compared with imported cores, the grade of Hainan ores is relatively low, but Hainan ores have good smelting performance and contains very few impurities. Usually, the proportion is 5%-10%. Therefore, imported and Hainan ores are complementary. The following sections offer detailed information.

 

1. Hainan Iron Ore Support Blast Furnace Process and Sintering

1. They can improve the burden design and adjust the alkalinity of slag. It is the preferred acid material for the blast furnace process.

The blast furnace process requires appropriate alkalinity. According to the principle of technology compliance and best cost, the optimum burden design accepted by the industry is the combination of high basicity sinter and acid materials. If the alkalinity of burden materials is too high, the blast furnace process will fail. There are three solutions for adjusting the alkalinity of slag: solution 1: adding silica. The shortcomings of this solution include: the proportion of silica is small; the distribution of silica in the furnace is not uneven; the reduction of furnace burden grade is large; and economic performance is poor. Solution 2: adding acid pellet. The shortcoming is that costs are high. Solution 3: adding Hainan ores with high silicon. The advantages of this solution include: good smelting effects, low reduction of furnace burden grade, better economic performance compared with solution 1 and lower cost compared with solution 2. Thanks to its above advantages, many steel enterprises preferentially choose Hainan ores for ore blending.

Because sinter shows significant cost advantages, steel enterprises inevitably consider improving the proportion of sinter to reduce their costs. In this case, using an appropriate amount of Hainan lump ores to replace some pellet or imported high-grade lump ores can bring significant cost advantages.

2. They can greatly improve slag fluidity.

Low content of SiO₂ and high content of Al₂O₃ in the blast furnace slag will result in very low fluidity of the slag, which will obstruct the processes in the furnace, and result in heavy workload of cleaning the slag ditch before the furnace. This is the case for most imported ores while content of SiO₂ is high in ores from Hainan Province, China, and the ratio of SiO₂/Al₂O₃ is large. So, it is very favorable to add certain amount of the ores from Hainan to regulate the quantity and components of the slag, reducing the content of Al₂O₃. By doing this, the fluidity of the slag can be improved significantly.

 

3. They can increase gas permeability in charge column of blast furnace and pulverized coal injection amount, and therefore reduce production costs.

Ores from Hainan are characterized by high decrepitation resistance performance, good decrepitation index, relatively high softening/melting temperature, narrow softening/melting range, low reduction disintegration index at low temperature, etc. which, being combined together, are favorable for improving the permeability in the charge column of the blast furnace worsened by increased pulverized coal injection as well as for realizing smooth processes in the furnace. Thus, the pulverized coal injection can be increased, and the production cost is reduced.

 

4. They have merits such as stable contents of components, even grain sizes, extremely low contents of impurities and good physical properties.

Ores from Hainan have stable contents of components, inherently characterized by high contents of iron and silicon, and by low contents of phosphorus and aluminum. the lump ores are 8-40mm in grain sizes, those with grain sizes of 10-35mm exceeding 75%, those with grain sizes less than 5mm only accounting for about 0.3%, and those with grain sizes less than 1mm being below 0.1%. Their even grain sizes make them better than lump ores from Brazil and Australia.

For the ores from Hainan, the contents of the impurities such as As, Zn, Na, Cu, Pb, etc. are extremely low. Generally, the contents of As and Zn are less than 0.005% respectively, and the contents of Na, Cu and Pb are less than 0.01% respectively.

 

5. They can provide better protection of blast furnace and extension of service life of its lining.

After a long period of operation or at the end of the service life of the blast furnace, the lining may fail gradually due to erosion resulting from the long-term scouring of the iron slag stream at the furnace hearth and bottom. A trace amount of TiO₂ in the ores from Hainan can form a small quantity of TiC and TiN deposited at the failed surface of the blast furnace after a period of time of operation with this kind of ore, generating a thin protective layer, which is favorable for protecting the lining from further erosion and extending the service life of the lining.

 

6. They can be used to produce ductile cast iron.

Due to their merits of high content of silicon and low content of phosphorus which is generally below 0.03%, ores from Hainan are very suitable for production of ductile cast iron. This becomes another important merit of them.

 

7. Sintering behavior of fine ores from Hainan

Due to its high content of silicon and iron, fine ore from Hainan is beneficial to the adjustment of silicon content of the sintered ores. Moreover, as 60% of the fine ores have grain sizes in the range of 3-8mm, which are favorable for nucleation and formation of quasi particles with only a little intermediates, the permeability of feed bed can be improved. Finally, high sintering strength of the fine ores can improve the quality of the sintered ores.

 

2. Comparison and Analysis of Economic Efficiencies

Main products of ores from Hainan include lump ore, fine ore and iron concentrate. Different products use different blending modes. The products are shown as follows:

Market prices quoted in a month of 2011:

Lump ore from Hainan with 55% iron and 17% silicon: RMB 1000/ton (CIF Tianjing Port, tax included, the same below);

Fine ore from Hainan with 52% iron and 17% silicon: RMB 750/ton (CIF Tianjing Port);

Iron concentrate from Hainan with 63% iron and 8% silicon: RMB 1300/ton (CIF Tianjing Port);

PB lump ores from Australia with 62% iron and 5% silicon: RMB 1400/ton (spot price);

Lump ore from Iran with 56% iron and 11% silicon: RMB 1100/ton (spot price);

Pellets with 61-62% iron and 5% silicon: RMB 1520/ton;

Silica: RMB 350/ton.

Blending mode 1: Hainan lump ores replace imported lump ores and silica and are directly fed into furnaces.

1. One ton of Hainan lump ores (55% iron and 17% silicon) are equivalent to a combination of 0.89 tons of Australian lump ores (62% iron and 5% silicon) and 0.126 tons of silica (98% silicon). The price of the combination is as follows:

1400 RMB/ton × 0.89 tons + 350 RMB/ton × 0.126 tons = 1290RMB/ton

This price is obviously higher than 1000RMB/ton of Hainan lump ores. This means that the cost of combination of PB lump ores and silica is considerably higher than the cost of Hainan lump ores if the iron grade is the same. Hainan ores can improve the burden design and adjust the alkalinity of slag while providing a high iron grade. This reduces costs of raw materials. In other words, buying Hainan ores means buying irons and getting free silica.

 

2. Compared with Iranian ores, one ton of Hainan lump ores (55% iron and 17% silicon) are equivalent to the combination of 0.98 tons of Iranian lump ores (56% iron and 11% silicon) and 0.063 tons of silica (98% silicon). The price of the combination is as follows: 1100RMB/ton × 0.98 tons + 350RMB/ton × 0.063 tons = 1100RMB/ton.

This shows that using imported ores at a low price to replace Hainan lump ores still does not bring outstanding advantage of price. Furthermore, a high content of ferrous oxides in Iranian ores, which is usually greater than 16%, will result in poor reduction performance so that coke ratio will increase if they are directly fed into furnaces. This makes blast furnace operation harder. In contrast, hematite from Hainan has a good reduction performance.

In conclusion, Hainan lump ores can adjust the alkalinity of slag and bring better economic performance than the combination of imported ores and silica.

Blending mode 2: Hainan lump ores replace acid pellet and are directly fed into furnaces.

In terms of smelting performance, both Hainan lump ores and pellet are acid furnace burdens. They can provide almost the same smelting effects, although the difference between iron grades is 6-7%. However, the price of one ton of Hainan lump ores is more than 500 RMB lower than that of pellet. Replacing pellet with Hainan lump ores can bring huge economic benefits.

Blending mode 3: use iron concentrate for sintering or palletizing.

For imported ores with low content of silicon, adding iron concentrate from Hainan, whose silicon content is about 6% and more than 80% of which has a grain size of 200 mesh, for sintering or palletizing is an ideal solution to adjust alkalinity of sinter and reduce costs of pellet. This solution brings good economic benefits.

Blending mode 4: use fine ores for sintering.

Fine ores from Hainan has a high sintering strength. For imported ores with low content of silicon, adding fine ores from Hainan, whose silicon content is 17%, for sintering can adjust alkalinity of sinter and improve the quality of sinter. It is a good blending solution. In addition, 60% of fine ores from Hainan has a grain size of 3-8mm and there are many nucleation particles. This is beneficial to the formation of quasi particles and improvement of permeability of feed bed.

 

Practices of many steel enterprises prove that adding an appropriate amount of Hainan ores to replace the combination of imported ores and silica or pellet can improve the production effects and economic performance. This is particularly significant for enterprises that use a large number of imported ores with low silicon content.

 

At present, the main users of Hainan ores include Wuhan Iron and Steel Group, Anyang Iron & Steel Group, Nanjing Steel Group, Beijing Shougang, Tianjin Iron, Sino-Iron, Guofeng Steel, Ma Steel, Ningbo Steel, Xinxing Ductile Iron Pipes, and Delong Steel. The biggest customer, Wuhan Iron and Steel Group, uses 0.7-0.8 million tons of Hainan ores annually.

 

 

Annex:

Technical Data of Hainan Iron Ore Products

Name	Analysis results (%)
	TFe	SiO2	S	P	Al2O3	CaO	MgO	K2O	Na2O	TiO2
Specification ore	55±2	17±2	≤0.9	≤0.08	＜1.5	＜1.0	＜1.0	＜0.2	＜0.04	＜0.12
Fine ore	52±2	17±2	≤0.9					＜0.14
Iron concentrate	63±2	≤8	≤0.25		＜0.8			＜0.2	＜0.02	＜0.08
Remarks: 1. Specification ore: grain size 8-40mm ≥75%, allowable water content: 1%. Based on the starting price under 54% TFe, the price per ton increases or decreases 10 RMB for every increase or decrease of 1.0%. 2. Fine ore: grain size 0-10mm ≥85%, allowable water content: 2%. Based on the starting price under 52% TFe, the price per ton increases or decreases 10 RMB for every increase or decrease of 1.0%. 3. Iron concentrate: grain size -200 mesh ≥80%. Based on the starting price under 63% TFe, the price per dry metric ton increases or decreases 10 RMB for every increase or decrease of 1.0%. 4. Hainan ores are hematite (Fe2O3) and the content of Ca, Pb and As is almost zero.（（

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