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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 2
Application of iron ore mud in powder form in portland cement presence
1. Introduction
1.1 Consumption of iron ore and environment
The Brazilian consumption of iron ore is concentrated in the pig
iron and pellets production. Based on production data for 2007
(35,5 Mt of pig iron and 55,0 Mt of pellets) and average consump-
tion rates provided by the companies (1,68 ton of iron ore/ton of pig
iron and 1,08 ton of iron ore/ton of pellets), it is estimated that the
Brazilian consumption of iron ore in 2007 was about 119,1 Mt (59,6
Mt in the manufacture of pig iron and 59,4 Mt in the manufacture of
pellets). Compared to 2006, the Brazilian consumption of iron ore
increased by 9.2%. Worldwide consumption of iron ore is about 1.6
billion tons (DNPM [1]). Forecasts of the Brazilian Mining Institute
indicate that investments in this sector will continue to grow over
the next 20 years. The industry has evolved greatly in the optimi-
zation of its production units in order to increase productivity and
meet the quality requirements and corporate sustainability.
The use that man has made of natural resources was not always
considering its features and capabilities of recovery. More recently
he became concerned about environmental problems. The emer-
gence of serious environmental problems, with consequences on
the man himself, led him to seek a better understanding of natural
phenomena and to understand that should act as part of the natu-
ral system (Mota [2]).
The environmental conservation represents for companies an unde-
niable responsibility. On the other hand, more and more the market
requires from companies a clear and concrete environmental preser-
vation and conservation performance, which is embodied for carrying
out activities that pose a minimal environmental impact (Ribó [3]).
1.2 Beneficiation of iron ore and waste generation
The studied waste is from Urucum Mineração S.A. belonging to
Grupo Vale, located in Urucum Hill in the municipality of Corumbá
(MS) 32 km away from downtown.
According to Lima [4], in this place the method of extraction of
eluvial ore that occurs at the top of the hill is open and it’s ac-
complished through embankments with a maximum height of 10
meters, no need for this exploration explosives, because the ore is
already broken down naturally.
Beneficiation process of iron ore consists of crushing, washing and
sieving. Iron ore is crushed and sieved on vibrating screens, in wet
process, which generate the products: granulated iron (6,35mm≤
Ø ≤38,10mm), small hematite (6,35mm≤ Ø ≤9,52mm), sinter-feed
(Ø ≤6,35mm) and mud.
The mud treatment system works as follows: effluent mud from the
washing of iron ore is carried by gravity through the channels until
a thickener, where the most solid and sediment is drained through
pipes to the tailing ponds located at the foot of the hill and the most
liquid returns to the washing process of iron ore by pumping.
The volume of water consumed in the process is approximately
60 m³/hour, with 60% recycled and 40% released in tailing ponds.
As the washing operation is continuous (24 h/day, 7 days/week),
you get a daily volume of mud in the order of 576.00 m³. Accord-
ing to analysis of Urucum Mineração S.A., the mud is composed
of approximately 40% solids and 60% water. In tailing ponds the
water evaporates and/or is reused in the process and the solids
settle, where you get, finally, a volume of solid material around
230.40 m³/day.
Among the products generated in the processing of iron ore, mud
from washing, in most cases, is stored in tailings dams without a
commercial use because the technology to transform this waste in
metallic iron is more expensive compared to other products.
An example of recovering iron from iron ore tailings is using the
technique of magnetizing roasting followed by magnetic separation
(Li et al. [5]). Also, Chinese researchers have developed a new
cementitious material in which 30% of its raw material is composed
of iron ore tailings, obtained through a process of great thermal
activation (YI et al. [6]).
1.3 Objective
This study aims to evaluate the mechanical performance of the
application of sludge of iron ore in powder form in Portland cement
mortars and thus, find answers regarding the technical feasibility of
this application and what the best mixture.
2. Materials and experimental program
Specimens were prepared with varying proportions of cement,
sand and iron ore mud in powder and, subsequently, subjected
Figure 1 – Ball mill (at left) and iron ore in powder form after drying and milling (at right)