Process for manufacturing of high iron hydraulic cement clinker

Details Process for manufacturing of high iron hydraulic cement clinker Process for manufacturing of high iron hydraulic cement clinker

2002-03-28

2004-06-22

Turner, Archene (Department: 1775)

Compositions: coating or plastic

Coating or plastic compositions

Inorganic settable ingredient containing

C106S739000, C106S745000, C106S749000, C106S769000, C264S333000

Reexamination Certificate

active

06752865

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for manufacture of high iron hydraulic cement clinker using a down draft sintering technique.
BACKGROUND OF THE INVENTION
High iron cement clinker is a non-portland type of cement clinker which contains iron (Fe
2
O
3
) to the extent of 40% and above as a major chemical constituent. The cement made from high iron cement clinker clearly possesses high binding strength on hydration. This type of high iron hydraulic cement is usable as a substitute to Portland cement in construction a special cement in sulphate resistance constructions, a metallurgical cement or a binder in briquetting, pelletisation and sintering of iron ore, iron oxide and metal containing fines for iron making and a hydraulic mineral binder for absorbing water soluble metals in the treatment and stabilization of hazardous toxic solid wastes.
Portland and aluminous cements are known cementitious systems in which calcium silicates and calcium aluminates respectively are the major cement mineral phases. Iron (Fe
2
O
3
) content in these cements are very low and ranges 2 to 6% in Portland cement and up to 15% (maximum) in aluminous cement. Iron and iron bearing mineral phases existing in these cementitious systems are quite insignificant quantitavely with respect to cement property.
Chemically and mineralogically the high iron cement is quite different from the Portland and aluminous cements. Iron (Fe
2
O
3
) in high iron cement is beyond the limit of the above two cements. Mainly, the calcium-iron and calcium-alumina-iron type of ferric phases are the major mineral constituents of high iron cement clinker responsible for developing hydraulic property and strength of the cement. Hydraulic property and development of strength of high iron cement largely depend on the mineral structure and degree of solid solution of different ferrite phase, crystallinity and presence of different calcium silicate and other mineral phases. In high iron cement clinker, the formation of different ferrite mineral phases mainly depend on the chemical parameters of calcium, alumina and iron; sintering and cooling conditions. Comparatively, ferrite mineral phases of high iron cement clinker form at a much lower temperature than the calcium silicates of the Portland cement clinkers. In respect to hydraulic property and strength, the performance of high iron cement is also better than the Portland cement.
Lime and iron bearing raw materials are the main source for the manufacture of high iron cement. Owing to the many advantageous qualities like cost effectiveness, energy efficiency and better performance of high iron cement than the Portland cement, the development of suitable processes in the production of high iron cement clinker in the present context has been given more attention.
At present, iron rich solid wastes are abundantly available in different metallurgical, chemical and mining industries. Accumulation of these wastes without proper use is a significant problem in respect of the environmental pollution caused. Thus, use of these types of waste materials may find a suitable value-added application in making high iron cements. Although some research activities have been carried out in past in this area but technological development in the production of high iron cement has not been made significant progress.
Reference is made to the following disclosures:
1. Kimenko Z. G; Tikhonov, V. A. Bobik, G. L; Petrovskaya, N. L.; Dmitrievskii, V. S.; Ozerov, V. M. (USSR). Visn L'Viv. Politekh. Inst. 1975, 95, 98-100 (Ukraine). Production of high iron cement for sintering iron ore concentrate (Chemical Ab.: 1975, 85: 1294451g).
2. Tikhonov, V. A; Klimenko, Z. G; Berezhnenko, E. T.; Zhavoronkova, E. V. (L'Viv. Politekh, Inst. L'Vov, USSR). Tr-Mezhdunar. Kongr. Khim. Tsem., 6
th
1974 (Pub. 1976), 3, 154-6 (Russ). Edited by Boldyrev, A S.; Stroiizdat: Moscow, USSR. Special highly ferruginous cement (Chemical Abs.: 1977, 86: 110385n).
3. Mehta, P. K. (Univ. of California). High iron oxide hydraulic cement. U.S. Pat. No. 4,036,657 (CI. 106-89, C04B7/02), 19 Jul. 1977, Appl. 598, 411. 23 Jul., 1975 (Chemical Abs.: 1977, 87: 121920e).
4. Buraev, M. L.; Tuzyak, V. e; Shpinova, L. G. (L'Viv. Politekh, Inst., L'Vov, USSR). Synthesis of alumina-iron oxide cement from red slime. Kompleskn Ispol'. Miner. Syr'ya, 1984 (2) 72-75 (Russ) (Chemical Abs.: 1985, 102: 50050h).
6. Feng. Xiuji, Zhu, Yufeng (Wuhan Inst. Build Mater. Wuhan, Peop. Rep. China). Research on an early strength cement containing high content of iron. Congr. Int. Quim. Cemento [An] 8
th
1986, 2, 285-92 (Eng) (Chemical Abs.: 1988, 109: 78641y).
7. Huo, Xingong; Zhen, Yinchum; Liu, Zhencai; Wang, Baoan; Wang, Suqing; Ruan, Doutian (Benxi Steel Co.) Faming Zhuanli Shenqing Gongkai Shoumingashu. Production of ferrite cement using highly activated slag from revolving furnace steel smelting. CN 87, 100, 826 (CI. C04B7/153), 16 Dec. 1987. Appl. 13 Feb. 1987 (Chemical Abs. 1989, 110: 43938u).
wherein efforts have been made to develop iron rich hydraulic cement clinker using the raw materials such as iron ore, red slime, steel melting slag by adopting conventional cement kilns and by smelting in steel smelting converters.
The drawbacks of the earlier processes are the limitations in the use of various types of iron rich raw materials, the deterioration of refractory life due to the formation of low temperature iron rich liquid phase, the difficulty in maintaining a proper reducing or oxidizing atmosphere and a faster cooling conditions to achieve the desired iron rich hydraulic cement mineral phases, involvement of more process steps to make clinker by using a steel smelting converter, the intensive energy required for the grinding of fused and melted iron rich clinker particles, etc.
OBJECT OF THE INVENTION
The main object of the invention is to provide a process for manufacture of high iron hydraulic cement clinker using down draft sintering technique which obviates the drawbacks as detailed above.
Another object of the invention is to maintain flexibility in the process in order to utilize a wide variety of raw materials, fines, solid wastes etc. containing lime and iron.
Still another object of the invention is to use coke, coal, char and carbon containing solid wastes as the source of fuel in the process.
Yet another object of the invention is to maintain easier raw material processing and sintering steps in the process to eliminate the use of refractories and high temperature melting operations.
Yet another object of the invention is provide an eco-friendly process and to use simpler plant machinery for commercial production in batch and continuous scale.
Yet another object of the invention is to maintain high productivity and low energy consumption in manufacture of high iron cements consisting of 40% iron (Fe
2
O
3
) and above.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a process for the manufacture of a high iron hydraulic cement clinker using a down draft sintering technique which comprises preparing a homogenous raw mixture of raw materials selected from limestone, lime, lime sludge, lime bearing solid wastes, iron ore, slime red mud, ferruginous bauxite, laterite, clay, iron oxide containing metallurgical and chemical wastes, slag, coke breeze, coal char, carbonaceous sludge, carbon bearing solid wastes and any mixture thereof, pelletising the resultant homogenized raw mixture in the presence of water to prepare granulated particles, sintering and cooling the pelletised granulated particles by down draft sintering technique to convert into clinker, grinding the clinker particles with and without gypsum to make high iron hydraulic cements and binders for different applications.
In one embodiment of the invention, the homogeneous raw mixture is prepared in semi-wet or dry form by blending or grinding, depending on the desired particle fineness.
In an embodiment of the invention, the chemical ratio of CaO/(Al
2
O
3
+Fe
2
O
3
), SiO
2
/(Al
2
O
3

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