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Showing posts with label Refractory Raw Materials. Show all posts
Showing posts with label Refractory Raw Materials. Show all posts

RHI inaugurates the largest fusion plant for Magnesia Raw Materials

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18-Nov-2012

RHI AG is a renowned name in the market, development, production and service of refractories. They are the Germany-based world leader in the field of refractories with 8100 employees and production facilities in about 32 countries and more than 100 locations around the world. Currently the total volume refractories produced by RHI AG is more than 2 million tonnes p.a. of Refractory Bricks (Refractory Bricks – Shapes and Sizes), Castables, Mortars and other functional products.
RHI has built and inaugurated one of the largest fusion plants for magnesia raw materials for more than 75 million euros in Norway in this month. In this fusion plant, magnesia obtained from sea water is converted to fused magnesia, which is a high-grade refractory raw material, at temperatures about 2800OC. With a capacity of approximately 85000 tonnes per year, the plant is one of the largest worldwide. According to RHI, 120 employees will work at the plant in full operation.

“We are increasing self-supply with magnesia raw materials, which are very important for the refractories industry, to 80% and thus continue to consistently pursue our strategy of backward integration. With this new plant, we will be completely independent from Asian fused magnesia imports. And we are shortening delivery routes to the European RHI sites”, said RHI CEO Franz Struzl at a press conference at the plant in Porsgrunn, Norway.
“The Porsgrunn location offers several advantages, including the infrastructure, the support of local politics and the energy costs in Norway. In addition, we have decades of experience, which gives us a very good command of the complex process of obtaining magnesia from seawater. The construction of the fusion plant is one of the largest onshore investments in Norway in five years and is planned as a long-term investment”, said RHI plant manager Roger Gravdal.
RHI acquired this fusion plant in Porsgrunn and another raw material plant in Drogheda (Ireland) last year. Both plants are based on the extraction of magnesia from sea water. RHI thus broadened its technological base in extracting refractory raw materials and increased the number of raw material plants to eight.
RHI mines magnesite and dolomite at six locations in Austria, Italy, Turkey and China in surface and underground mining. RHI produces about 1 million tonnes of refractory raw materials per year.
The advantage of fused magnesia from Norway lies in its highly refractory properties caused by the firing process by means of electrofusion, in which the crystalline structure magnesia is improved significantly and the magnesia (MgO) content is increased to nearly 100%.
Fused magnesia from Norway is primarily used at the European RHI plants Veitsch (Austria), Radenthein (Austria), Aken (Germany) and Duisburg (Germany) and processed to end products for the steel, cement, lime, refractory and some nonferrous Metals industries.
(Source: RHI)  

Dissolution Kinetics of MgO-CaO and MgO-Cr2O3 (Mag-Chrome) Refractories in Secondary Steel Slag and the Binary Phase Diagrams

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MgO-CaO Phase Diagram
Refractory Lining: MgO-CaO Binary Phase Diagram image
Fig: MgO-CaO binary Phase Diagram

The above figure shows the phase diagram of MgO-CaO binary system. The solid solubility at high temperatures leads to formation of a high temperature bond in dolomite refractories.   
MgO-Cr2O3 System (MgO-MgCr2O4 Phase Diagram)
Refractory Lining | Steel Technology: MgO-MgCr2O3(Magchrome spinel)
Fig: MgO-MgCr2O4 binary Phase Diagram

The only intermediate compound which exists in the binary system MgO-Cr2O3 is Magchrome spinel (MgO.Cr2O3 or MgCr2O4). From the above phase diagram of Magnesite-Magchrome spinel (MgO-MgCr2O4) binary system it can observed that for steel plant refractories direct bonding between magnesia-chrome phase is formed when these two are heated together at temperatures above 1600OC as a result of the partial solubility of the constituents.      
Dissolution Kinetics of Refractory Oxides
Refractories are non-metallic materials used for the lining of kilns and furnaces required for high temperature operations in several metallurgical and non-metallurgical industries such as iron & steel, aluminium, copper, glass, cement, petrochemicals etc.
Dissolution of solid oxides in liquid slag is governed mainly by –
(1) Chemical reaction at the slag / refractory interface,
(2) Transport or diffusion of reacting species.
In the second case, rate of dissolution can be expressed in terms of Nernst equation:
J = D (Cs – Cm) / ∂
Where, D is the diffusion coefficient (m2 s–1), Cm and Cs are, respectively, concentration and saturation solubility of refractory in slag (g m–3), and ∂ is the effective boundary layer thickness (m). Increasing D or decreasing ∂ (i.e. increasing D/∂) result in increase of dissolution rate, J. Moreover, it is also clear from the above equation that the value of (Cs – Cm) strongly influences the dissolution rate. If slag is saturated with refractory oxide then J = 0. Naturally, to minimize rate of dissolution, it is necessary to minimize (Cs – Cm). For example, with increasing MgO content in the slag, the corrosion of the periclase phase in Mag-Chrome refractories will decrease. If Cm = 0, then the value of (Cs – Cm) reaches a maximum and thus, so does the dissolution rate.
Dissolution kinetics of MgO-CaO and Magnesite-chrome refractories in secondary steel slag was studied by Chen Zhaoyou Wu Xuezhen Ye Fangbao at Luoyang Institute of Refractories Research by means of the rotating cylinder method [See details]. Materials investigated include four MgO-CaO samples (MgO content: 40 to 93%) and two magnesite-chrome samples (co-clinkered and semi-rebonded). The experiments were carried out in Argon atmosphere at different temperatures (1600-1750OC) and revolution speeds (200 to 500 rpm) using synthetic slags similar to VOD and AOD slags with different basicities (0.6-2.68). Based on their experimental results the mechanism and kinetics of the dissolution process are discussed. The conclusions drawn are as follows:
1. Erosion resistance of magnesite-chrome (MgO-Cr2O3) refractories is better than that of MgO-CaO materials.
2. When the content of MgO is about 60-80%, slag dissolution resistance of MgO-CaO samples will be comparatively higher. When basicity of slag is 1.0, the dissolution rate of magnesite-chrome refractories (i.e. Mag-Chrome, MgO-Cr2O3) is much lower than that of MgO-CaO.
3. With increase of basicity of slag, the dissolution rate of magnesite-chrome increases, whereas that of MgO-CaO decreases.
4. For the increase of temperature of 100OC at one time, the dissolution rate of MgO-CaO increases by 2-3 times while that of magnesite-chrome increases 5-6 times. Dissolution activation energy for MgO-CaO refractory is 70 kcal/mol and that for magnesite-chrome is 110 kcal/mol. The diffusion coefficient of MgO in the slag is 3.7×10~(-5)cm~2/s.
5. M_2S is formed by magnesite-chrome with acid slag in the reaction zone while C_2S is formed by MgO-CaO with basic slag in the reaction zone.
6. The process of dissolution of MgO-CaO refractories in slag is controlled by the diffusion mechanism.      

Indian China Clays: Occurrences, Uses and Properties

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6-March-2010
Both China clay and Ball clay belong to the kaolin group. Although the primary constituent is Kaolinite in both of them, the latter has greater plasticity and lesser refractoriness owing to the presence of Montmorillonite in considerable amounts. So, ball clay is normally added to china clay to achieve greater strength, increase refractoriness and the required plasticity. To discuss all aspects of ‘China Clay’ in one post would be quite a long one and a reader who is searching a specific topic about china clay, may not like to go through the whole article. So, we have divided the different topics of china clay like - its beneficiation, improvement in its quality (benefit) after different treatments of beneficiation, characteristics (properties) of china clay required for different industries etc. into separate posts. Here we will discuss the following:
=> Properties and occurrences of china clays particularly in India.
=> Uses of china clay in general.
=> A few addresses of Mines (also Suppliers) of Indian china clays along with their sample Test Reports given at the end.   

Properties and Occurrences of China Clay in India
As for genesis, both China clay and ball clay are the products of weathering processes of feldspathic rocks. What happens during weathering that the silica and iron oxides are partially leached with the residue (essentially an aluminium silicate in composition) forming the in-situ deposits. Depending upon the efficiency of the weathering process, the impurities like grit i.e. siliceous particles and iron oxide minerals exist in different percentages in different clay deposits.
India has extensive deposits of china clays distributed in almost all states. However, good deposits are found Chaibasa, Singhbhum (near Ranchi, Jharkhand), Mokdum Nagar, Kharidumri, Suri, Qasim Bazaar all in Bankura, Birbhum districts (West Bengal), Barmer, Pali, Bikaner, Ajmer, Nim-ka-Thana, Udaipur (Rajasthan), Anantpur, Nellore and Guntur (AP), Chanda, Ratnagiri (Maharashtra), Udhampur (J & K). Very good quality china clays are found in Kerala in Kundra (Quilon), Ernakulam and Trivandrum districts. The estimated total reserve of crude clay is around 7.5 lakh tones. The spray dried kaolin is marketed under the trade name “Kundara Kaolex”. The average chemical analyses of some Indian china clays are presented in the following table.         
   Table: Chemical Compositions (in %) of some Indian China Clays 
SOURCE
SiO2
Al2O3
Fe2O3
TiO2
CaO
MgO
K2O
Na2O
LOI
Gujarat
Kutch Minerals
Ashapura
AMI China Clay
Eklera

47.75
49.63
52.45
48.92

34.25
34.00
29.83
33.60

0.90
0.60
0.94
1.30

1.30
1.37
1.48
1.12

1.23
0.54
1.14
0.65

0.24
0.58
0.59
0.28

0.35
0.22
0.35
1.00

0.45
0.61
0.86
0.31

12.45
12.20
11.90
12.80
Bihar - Jharkh
Rajmahal (pink)
Rajmahal (white)
Chaibasa - I
Chaibasa (S.Fine)
Simultala

46.68
48.90
47.90
46.59
47.30

35.29
34.51
36.00
35.95
38.20

1.90
1.71
1.25
1.12
0.47

0.90
0.50
Tr.
Tr.
0.07

0.28
0.67
1.24
1.40
0.35

0.50
0.20
0.40
0.40
0.10

0.28
0.41
0.61
0.33
1.55

0.60
0.52
0.75
0.90
0.15

13.12
12.60
12.25
13.22
11.80
West Bengal
Mokdum Nagar
Mohammad Bazaar

44.10
44.30

37.39
36.69

2.60
2.10

1.37
0.80

0.10
0.30

Tr.
0.26

0.20
0.60

0.75
0.29

13.48
14.35
Rajasthan
Modi Clay (P-90)
Modi Clay (TT-75)

44.46
46.82

37.03
36.70

0.80
1.00

Tr.
0.20

2.00
0.70

0.41
0.25

0.07
0.15

1.02
0.20

14.65
13.87
Kerala
Marthandamkonam
Kundara, Quilon
English India
Chilambil, Trvndrm
Sasthavattom

46.47
45.83
46.30
45.60
44.11

38.13
38.17
38.80
37.40
38.17

0.28
1.43
0.50
0.75
1.30

0.79
0.40
0.10
0.90
1.55

Tr.
0.90
0.02
Tr.
Tr.

0.59
0.12
0.07
0.41
0.04

0.02
0.25
0.07
0.02
0.02

0.08
0.72
0.08
0.02
0.43

14.20
14.00
14.10
14.85
14.26
Tamil Nadu
Neyveli Clay

45.00

36.72

0.38

1.75

0.55

Tr.

0.03

0.24

14.24

Uses of China Clay
China clay is used in rubber, ceramic, textile, paint, pharmaceutical, paper, cosmetic industries and also as in refractory industry for the production of insulation bricks, insulation mortars and castables [Refer to our separate post Use of China Clay as Raw Material in the Production of Refractory Insulation Bricks].
In ceramics china clay is widely used in manufacturing earthenware, fine china, stoneware, tiles, pipes etc. Usage of china clay for ceramic industry depends on factors like - plasticity, shrinkage after drying and on firing, colour on firing, refractoriness etc. The grit content should be around 1%.
The fine grained kaolinites (China clays) mixed with montmorillonites find applications in foundry moulding sands. Purer forms of china clays have extensive uses in paper, textile, rubber and cosmetic industries. [Refer to our separate post Characteristics of China Clay Required for Ceramic and Other Industries].
As a decolouriser of oils it is known as ‘Fuller’s Earth’. Mixtures of china clays and montmorillonites are also used as cracking catalysts for heavy petroleum fractions. Other areas of limited use are leather, paint, plastics, soaps, polishing compounds, emulsifying agents etc.        
Mines and Suppliers
Below are addresses of some of the above mentioned mines (also suppliers) of china clays of different grades form Bihar, Jharkhand and West Bengal whom I visited during 2005 - 2006 accompanied by the test results of the china clay samples that were drawn and collected by myself during my visits to these mines.
Chaibasa (Singhbhum) China Clay
Address:
Singhbhum Mineral Co., Post Box No. - 24, Station Road, PO- Chaibasa
PIN - 833 201 (Jharkhand).
Contact person: Hemant Rathore (Mine owner)
Tel: 91-6582-256551/258336
Mob: 91-9431110051.
Mine address:
Singhbhum Minerals, Hatgamharia, Chaibasa (Jharkhand).
Sample Test Report (average report):
1. Sample = China clay (RT grade), drawn from Pit No.9.
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 15%
Characteristics = White, clean, no spot.
LOI % - 11.6 
Al2O3% (min) - 36.0
Fe2O3% (max) - 1.7
TiO2% (max) - 0.15
2. Sample = China clay (pink variety)
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 17%
Characteristics = Pinkish White, clean, no spot.
LOI % - 11.5 
Al2O3% (min) - 33.52
Fe2O3% (max) - 3.04
TiO2% (max) - 0.15
3. Sample = China clay (RT grade, upper layer) drawn from Pit No.9.
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 15%
Characteristics = White, clean, no spot.
LOI % - 11.6 
Al2O3% (min) - 36.28
Fe2O3% (max) - 1.9
TiO2% (max) - 0.12

Mine address:
D.M.Minerals, Gondkida Mines, Hat Gamharia, Chaibasa (Jharkhand).
Sample Test Report (average report):
1. Sample = China clay (Special/Rubber grade)
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 16%
Characteristics = Milky white, clean, without any spot.
LOI % - 14 
Al2O3% (min) - 36.0
Fe2O3% (max) - 1.92
TiO2% (max) - 0.25
2. Sample = China clay (crude, unwashed)
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 12%
Characteristics = Pinkish White, clean, no spot.
LOI % - 13.8 
Al2O3% (min) - 36.00
Fe2O3% (max) - 1.96
TiO2% (max) - 0.02
3. Sample = China clay (SF grade)
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 16%
Characteristics = Milky white, clean, no spot.
LOI % - 14.4 
Al2O3% (min) - 36.44
Fe2O3% (max) - 1.39
TiO2% (max) - 0.40

Address:
Gupta Minerals, PO- Hat Gamharia, Dist.- West Singhbhum
PIN - 833 214 (Jharkhand).
Contact person: Ajay Kr. Gupta (Mine Owner & Supplier)
Tel: 91-6589-285267
Mob: 91-983213463, 91-9835142033
Sample Test Report (average report):
Sample = China clay (SF grade)
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 17%
Characteristics = Buff, Off-white.
LOI % - 10.0 
Al2O3% (min) - 33.0
Fe2O3% (max) - 2.8 - 3.0
TiO2% (max) - 1.0
(CaO + MgO) - 0.5
Na2O - 0.88
K2O - 1.38
PCE - 30 (Orton)
Address:
Chotanagpur Commercial Corpn. (P) Ltd.
Post Box - 54, Chaibasa Dist.- West Singhbhum
PIN - 833 201 (Jharkhand).
Contact person: R.P. Rungta (Supplier)
Tel: 91-6582-256062, 91-33-22101235/1236
Mob: 91-9431110291
Sample Test Report (average report):
Sample = China clay
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 14 - 15%
Characteristics = Yellowish white, clean.
LOI % - 12.0 
Al2O3% (min) - 31.38
Fe2O3% (max) - 3.36
TiO2% (max) - 0.30
PCE - 29 - 30 (Orton)
Lohardaga China Clay (Near Ranchi, Jharkhand)
Address:
Regal Sales and Marketing, Lohardaga, Ranchi
Sample Test Report (average report):
Sample = China clay (INDAL Type)
Total Shrinkage (after drying & firing 1300OC/2 hrs) = 7%
Characteristics = Milky white, clean.
LOI % - 14.0 
Al2O3% (min) - 37.00
Fe2O3% (max) - 1.35
TiO2% (max) - 3.0
PCE - 32+ (Orton)
Bhilwara (Rajasthan) China Clay
Address:
Bhilwara China Clay Suppliers
Main Bazaar, Bhilwara (Rajasthan)
Sample Test Report (average report):
Sample = China clay
Total Shrinkage (after drying & firing 1400OC/2 hrs) = 16%
Characteristics = Greenish white, clean, minor crizzling.
AP = 5.5
BD = 2.5 gm/cc
LOI % - 13.5 
Al2O3% (min) - 37.0
Fe2O3% (max) - 1.4
TiO2% (max) - 4.0
PCE - 32 (Orton)
Suri, Birbhum China Clay (West Bengal)
Address:
A.K. Industries Pvt. Ltd.,
P-7, Dr. Suresh Banerjee Road, Kolkata - 85.
Tel: 91-33-23505765/25348349/25533737
Mob: 91-9831219022
Contact person: Soumendu Nag
Mob: 91-9434007964.
Mine address:
A.K. Industries Pvt. Ltd. Village - Kalipur
P.O.-Barabagan, Suri
Dist. - Birbhum (WB).
Tel: 91-3462-225423
Sample Test Report (average report):
1. Sample = China clay
Total Shrinkage (after drying & firing 1400OC/2 hrs) = 18%
Characteristics = White, clean.
AP = 10%
BD = 2.42
LOI % - 14 
Al2O3% (min) - 37.0
Fe2O3% (max) - 2.3
TiO2% (max) - 2.5
PCE = 33 (Orton)
Address:
Patelnagar Minerals & Industries Pvt. Ltd. (PMI),
20B, Abdul Hamid Street (1st Floor), Kolkata - 700069.
Tel: 91-33-22486915/22486928/23371276
Fax: 91-33-22489546
Contact person: A.Ahmed (Chief Executive)
Tel: 91-3462-260245/260213
Mines and Refinery address:
PMI Private Ltd., Patelnagar, Suri
Dist. - Birbhum (WB)
Tel: 91-3462-260225/260223
Sample Test Report (average report):
Sample = China clay (Refractory grade)
[All grades of china clay are available with them suitable for rubber, textile, cosmetic, paint and paper industries.]
Total Shrinkage (after drying & firing 1330OC/2 hrs) = 18%
Characteristics = Off-white, clean.
AP = 7%
BD = 2.5
LOI % - 14 
Al2O3% (min) - 37.0
Fe2O3% (max) - 2.0
TiO2% (max) - 3.0
PCE = 32½ (Orton)

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