FIELD OF THE INVENTION
The present invention generally relates to making soil amendments from waste
of iron ore slime beneficiation process and low grade iron ore beneficiation. More
particularly, the invention relates to a process of generation of waste through
beneficiation of iron ore slime, characterization and conversion of this waste
material to soil amendments.
BACKGROUND OF THE INVENTION
Iron ore is the major raw material for iron and steel industry. Indian iron ore
contains alumina (AI2O3) as the major impurity. Alumina in iron ore decreases hot
metal productivity in Blast Furnace and adversely affects cost of steel production.
Therefore, alumina content in the iron ore is known to be lowered through
beneficiation to an acceptable level of 2.2% from feed alumina level of 3.0-4.0%
and more. Beneficiation process generates rejects in the form of iron ore slimes.
Presently, around 15-20% of the feed treated in beneficiation plant is rejected as
iron ore slime. Iron ore slime also contains liberated iron ore particles.
However, the present applicant have already disclosed and filed patent
applications in India relating to the process for beneficiation of iron ore slime to
recover iron values from ultrafine fraction of iron ore slime for example, of size
45 microns and below. This process recovers iron ore concentrate containing
2.2% alumina from a feed containing 7-10% alumina. The concentrate yield is
around 45 - 50%. Reject generated from beneficiation of iron ore slime can be
treated as waste as iron content in the reject is below 40%. Furthermore,
liberation characteristics of iron minerals and associated gangue minerals are
complex, hence recovering iron values from this reject through benefication is
not feasible.
Therefore, reject from iron ore slime beneficiation is considered as waste and
effective utilization of this waste is required for making iron ore beneficiation a
zero waste technology.
Soil is the top layer of earth crust on which plant grows. It is primarily composed
of weathered minerals matter, organic matter and pores filled with water and air.
Soil must contain few primary nutrients such as Nitrogen (N), Phosphorus (P)
and Potassium (K), lack of which inhibits plant growth. Among these three
elements, nitrogen content in soil is measured as soluble nitrate, available
nitrogen and total nitrogen. Nitrogen availability in all three forms is part of soil
characterization. There are few physical properties of soil which assist nutrients
delivery from soil to plant and helps in crop growth. These properties are pH,
electrical conductivity (EC), maximum water holding capacity and Cation
Exchange Capacity (CEC). Waste from slime was characterized based on all these
properties. Additionally, Organic Carbon (OC) and iron content of slime were also
measured since, organic carbon is an important constituent of soil and waste
from slime is expected to contain high proportion of iron.
Prior art survey shows that mineral rich soil is used for (i) treatment of industrial
waste, (ii) water treatment with respect to removal of total suspended solids, (iii)
soil for slow release of nutrients and, (iv) soil as additional source of specific
nutrients. US patent 4353749 and 4331538 are on treatment of acid industrial
waste generated from calcium sulphate and phosphates deposit. Soil which is a
mixture of fly ash, iron and aluminium oxide rich particles is used for this type of
industrial water treatment. Ground water can be purified using iron particles (US
patent 0163172) or microbial assisted iron particles (US patent 5543049). Acidic
waste water can be treated with rock wool and other inorganic binder and it
helps to reduce iron and sulphate ions form water (US patent 7048860). Mineral
slime along with fly ash and other waste helps in improving water quality by
reducing total suspended solids (US patent 3932275 and US patent 3509047).
Mine tailings are often used as source of soil nutrients. Mine tailings from
sulphide mines is useful source of Sulpher. These types of tailings are treated at
high temperature along with sulphuric acid and ammonia prior to its use as soil
conditioner. Gypsum, silica sand and coal dust from mine tailings are used as
additives in the soil which helps in slow release of nutrients to crop and thus
helps in sustained crop growth and also helps in maintaining soil fertility for
longer duration (US patent 7731775).
OBJECT OF THE INVENTION
It is therefore an object of the invention to propose to a process of
characterization and conversion of waste materials from iron ore slime
beneficiation, which eliminates the huge of waste material produced in iron ore
slime beneficiation method.
Another object of the invention is to propose a process of characterization and
conversion of waste materials from iron ore slime beneficiation, which is enabled
to convert the waste material as a substance to improve the soil quality leading
to agricultural revolution.
SUMMARY OF THE INVENTION
According to the invention, waste from iron ore slime is tested for its suitability of
using as a substance to improve soil quality. These tests were carried out in four
different stages. In the first stage, the waste material is converted by treating
with organic matter. In the second stage, tests are conducted under a simulated
condition representing a soil-phase necessary at the beginning of crop
cultivation. Thus, soil is tested along with organic matter at high moisture level
for its soil characteristics. In the third phase, along with the organic waste
matter, fertilizer enriched with Nitrogen (N), Phosphorus (P), and Potassium (K),
was used in the waste material for its use as soil amendment. The produced
(serial) Boro rice was then tested for its nutrient contents at different stages of
crop growth. These tests indicate suitability of the organically converted waste
material in supplying nutrients to crop at its different stages of growth. The
fourth phase of tests was carried out following phase three. However, crop used
for these tests was cabbage. All these tests indicate that the waste material from
iron ore slime and soil at a ratio of 1:3 and 1:4 along with organic matter and
N,P,K is suitable for growth of crops such as serial (Boro rice) and vegetables
such as (Cabbage).
DETAILED DESCRIPTION OF THE INVENTION
A process for beneficiation of 7 to 10% alumina iron ore slime with particle size
below 45 microns is known. This process generates concentrate of 2.2% alumina
which is a feed for pellet plant. Waste generated from this process contains iron
values less than 40% with alumina content 15% and more. Further recovery of
iron values from this waste is not possible due to its extreme complex liberation
characteristics. Total five patents have been filed to protect this process. On an
average 50% of iron ore slime goes as waste at the end of slime benefication.
Accordingly, the present invention proves to a process of characterization and
conversion of waste materials from iron ore slime benefication.
Table 1: Characteristics of waste from iron ore slime (Soil amendment)

The results show that the amount of total N, available N, Exchangeable
ammonium, available K and available Al has been recorded as 0.027%,
156.8mg/kg, 112mg/kg, 15.4 mg/kg and 4.5mg/kg. With low organic carbon
(0.08%) and CEC (4.5 cmol (p)/kg) the waste from iron ore slime beneficiation
fairly attains a substantially higher soil fertility status.
It is in this direction, waste from iron ore slime is tested for its suitability of using
it as a substance to improve soil fertility. These tests were carried out in five
different stages. In the first stage, the waste material is treated with organic
matter, and in the second stage, the converted waste material is tested for its
soil characteristic at high moisture level. This simulated condition represents a
condition synonymous to a condition prevailing at the beginning of rice and other
seasonal crop cultivation. In the third phase, along with organic matter, fertilizer
enriched with Nitrogen (IM), Phosphorus (P), and Potassium (K) are used in the
waste and used for cultivation of serials (Boro rice). This crop was then tested
for its nutrient contents at different stages of crop growth. These tests indicate
suitability of the converted waste substance towards supply of nutrients to crop
at its different stages of growth. The fourth phase of tests was carried out
following phase three. However, crop used for these tests were cabbage. All
these tests indicate the waste material and soil at a ratio of 1:3 and 1:4 along
with organic matter and N,P,K is suitable for growth of crops such as serial (Boro
rice) and vegetables such as (Cabbage).
TESTING METHODS
The waste from iron ore slime was tested for soil characteristics and then
compared with typical soil. Characterization of different physical and chemical
parameters is carried out following standard method such as water holding
capacity ( Black, 1965), pH (Page et al, 1982), EC (Jackson, 1973), Oxidisable
organic carbon by Walkley and Black method (Nelson and Somners, 1982), Total
N, Available K, Nitrogen (by Bremner and Keeney method, 1966).
Table 2: Physical and chemical characteristics of soil and slime.

Table 2 shows pH, CEC, organic carbon content, water holding capacity (WHC)
and available nutrient contents from waste of iron slime is either better than soil
or comparable to normal soil. Therefore, tests are conducted to improve the soil
conditions with respect to physical, chemical and biological attributes using waste
from iron slime as amendment. Secondly, tests are carried out to evaluate soil
nutrient supplying power of the soil when mixed with waste from iron ore slime.
Finally, tests are carried out to evaluate waste from iron slime as a substance to
improve soil quality for different types of crops under green house and field
conditioning. Total three sets of tests were carried out to evaluate performance
of waste of iron ore slime as soil-condition improver. The third set of test was
carried out on boro rice and cabbage. Experimental conditions and outcome of
these tests are discussed below:
Test 1: Effect of organic matter and soil amendment on changes in physical and
chemical properties of soil.
Test Conditions:
• Tl = Soil
• T2 = Soil + Organic matter
• T3 = Soil + Waste from iron ore slime (1:1)
• T4 = Soil + Waste from iron ore slime (1:1) + Organic matter
• Design : Completely Randomised Design
• Replication: 3
• Duration: 90 days
• Sampling days: 30, 60 and 90 days of incubation
• Items of analysis: pH, EC, OC%, Available N, Total N, Available P and
Available K
Test Results:
Table :. Effect of organic matter on the changes in pH of iron slime

The result shows that the combined application of organic matter and waste
from iron slime along with soil maintained almost neutral in reaction compared
to soil plus organic matter, soil plus waste from iron slime and soil.
Table 4. Effect of organic matter on the changes in EC (dSm-1) of the
iron slime

Table 5. Effect of organic matter on the changes in organic carbon
content (%) in soil and iron slime

With regards to the changes in organic carbon content, it was found that the
amount of organic carbon content was maintained a greater value in the
treatment where soil+ waste from iron slime plus organic matter were applied
together compared to other treatments. The result suggested that iron slime has
some favourable characteristics for binding organic carbon in the iron slime
matrices in presence of organic matter compared to other treatments.
Table 6 Effect of Organic Matter on the changes in available nitrogen
content (%) in soil and iron slime.

Table Effect of Organic matter on the changes in total N content (%) in
soil and iron slime-

Table 8 Effect of organic matter on the changes in available
phosphorus in soil and iron slime.

i
Table 9 Effect of organic matter on the changes in potassium content
(mg/kg in soil and iron slime.

The result show that the amount of available N,P,K and total N contents have
been found to be increased with the application of organic matter. The amount
of those nutrients were although recorded a higher amount in soil+ organic
matter treatment but the highest value of those nutrients were recorded with
soll-h waste from iron slime + organic matter treatment. From this study, it has
been found that the use of iron slime mixing with normal soil and organic matter
may be beneficial in enhancing soil fertility and crop production.
Test 2: Effect of moisture regime and soil amendment on changes in physical
and chemical properties of soil.
Test Conditions:
• 71 = Soil
• 72 = Soil + Waste from iron ore slime (1:1)
• 73 = Soil + Waste from iron ore slime (1:1) + Organic matter
• Design: Completely Randomised Design
• Replication: 3
• Duration: 90 days
• Sampling days: 0, 45, 60 and 90 days of incubation
• Items of analysis: pH, CEC, OC% and Available N
Table 10 Influence of moisture regimes on the changes in pH of iron
slime in treated with and without organic matter.

A=Treatment materials kept at 60% water holding capacity (WHC)
B= Treatment materials kept under water logged condition.
Table 11 Influence of moisture regimes on changes in
cation exchange capacity. CEC(cmol(p+)/kq) in iron slime treated
with and without organic matter.

A=Treatment materials kept at 60% water holding capacity (WHC)
B= Treatment materials kept under water logged condition.
Table 12 Influence of moisture regimes on changes in organic
carbon content in iron slime treated with and without organic
matter.

A=Treatment materials kept at 60% water holding capacity (WHC)
B= Treatment materials kept under water logged condition.
Table 13 Influence of moisture regimes on changes in available N
content (%) in iron slime treated with and without organic matter.

A=Treatment materials kept at 60% water holding capacity (WHC)
B= Treatment materials kept under water logged condition.
The results shows that the amount of organic carbon increased when waste from
iron ore slime it amended with organic matter irrespective of moisture regimes.
The magnitude of such increase, however, further enhanced in iron slime when it
is waterlogged after amending with organic matter.
In the next step, soils and plant sample are periodically analysed with regard to
different plant nutrients and their concentration in the plant. Studies were
conducted on boro rice and cabbage in the green house with the following
treatments:
Test 3A: Effect on crop (Boro rice) when soil amendment is used in the soil Test
Conditions:
• Tl = Soil
• T2 = Soil +NPK (100:50:50) +FYM
• T3 = Soil +NPK (100:50:50)
• T4 = Slime
• T5 = Slime +NPK (100:50:50) +FYM
• T6 = Slime +NPK (100:50:50)
• T7 = Soil+Slime(l:l)
. T8 = Soil +Slime (1:1)+NPK (100:50:50) +FYM
. t9 = Soil +Slime (1:1)+NPK (100:50:50) T10 = Soil+Slime (2:1)
• Tn = Soil +Slime (2:1)+NPK (100:50:50) +FYM
• T12 = Soil +Slime (2:1)+NPK (100:50:50)
• Design: Completely Randomised Design
• Replication: 3
• Crop: Boro rice
• Variety: Satabdi IET - 7786
• Duration: 105 days
• Sampling days: 0, 45, 60, 90 and 105 days of incubation
• Items of analysis: OC% and Available K
• Plant sample were collected at three different stages and analysed for N,
andK.
Table 14. Average Potassium (K) content in soil at different growth
phase of rice.

Table 15. Total Nitrogen (N) content in rice plant at different growth
phase.

Results show soil and slime (of ratio of 2:1) with recommended dosage of NPK
provides nutrients to rice crop during its growth and this result is better than soil
+ recommended dosage of NPK. This supports the role of waste from iron ore
slime as a soil condition improving substance.
Test 3A: Effect on crop (Cabbage) when converted waste materia is used in the
soil Test Conditions:
• Ti = Soil + NPK +FYM
• T2 = Soil +Slime (1:1)+NPK+FYM
• T3 = Soil +Slime (2:1)+NPK +FYM
• T4 = Soil +Slime (3:1)+NPK+FYM
• T5 = Soil +Slime (4:1)+NPK +FYM
• T6 = Slime +NPK+FYM
• Replication: 3
• Crop: Cabbage
• Variety: NL - 183
• Duration: 90 days
• Sampling days: 0, 30, 60 and 90 days of incubation
• Items of analysis: OC%'and Available N, P and K
• Plant sample were collected at three different stages and analysed for N.
Test Results:
Table-16: Changes in organic carbon % in Cabbage during various
stages of crop growth.

The results show that the amount of organic carbon content on iron slime
growing cabbage has been found to be increased in the highest amount (0.50%)
at 45 days if crop growth treatment where soil : slime mixed in the ratio of 4:1
along with NPK and FYM. From the results it may be concluded that mixing of
soil with iron slime in different ratios might be useful in augmenting soil nutrient
status as well as improvement of organic carbon content in the amended soil.
Table-17: Changes in Exchangeable ammonium (mg/kg) in
Cabbage during various stages of crop growth.

The changes in exchangeable ammonium content (Table-2d) in soil has been
found to be increased highest content (411.49 mg/kg) in the treatment where
soil: slime mixed in the ratio of 1:1 along with NPK and FYM which was closely
followed by the treatment where soil: slime mixed in the ratio of 3:1 along with
NPK and FYM.
Table-18: Changes in Soluble nitrate (mg/kg) in Cabbage during
various stages of growth.

Table-19: Changes in Available N (mg/kg) in Cabbage during various
stages of crop growth

The results for the changes in nitrate nitrogen and available N content in the
treated slime are presented in table 18 and 19. The amount of nitrate N and
available N content have been found to be increased highest the treatment
where soil: slime mixed in the ratio of 3:1 along with NPK and FYM. The overall
results suggested that the management of iron slime through mixing with either
3:1 or 1:1 or 4:1 along with NPK and FYM might be useful in improving soil
fertility and soil health vis-a-vis growing crops.
WE CLAIM
1. Present invention is related to the development of soil conditioner
(amendment) from waste of iron ore slime beneficiation. The invention
further relates to the development of a new method in making soil
amendments from waste of iron ore beneficiation and thus making iron
ore beneficiation a zero waste technology.
2. Characterisation results show pH, CEC, organic carbon content, water
holding capacity (WHC) and available nutrient contents from waste of iron
slime is either better than soil or comparable to normal soil. Therefore,
addition of waste from iron ore slime beneficiation improves the soil
conditions with respect to physical, chemical and biological attributes.
3. In the first stage, soil amendment is tested for its soil characteristics after
it is treated with organic matter. This is to simulate a condition that
prevails during the beginning of any cultivation. In the second phase, soil
amendment is tested for its soil characteristics at high moisture level. This
simulated condition represents a condition essential at the beginning of
rice and other seasonal crop cultivation. In the third phase, along with
organic matter, fertilizer enriched with Nitrogen (N), Phosphorus (P), and
Potassium (K) soil amendment was also used in soil for cultivation of Boro
Rice. This crop was then tested for its nutrient contents at different stages
of crop growth. These tests indicate suitability of soil amendment in
supplying nutrients to crop at its different stages of growth. The fourth
and the last phase of tests were carried out following phase three
procedure. However, crop used for these tests was cabbage.
4. With regards to the changes in organic carbon content, it was found that
the amount of organic carbon content was maintained a greater value in
the treatment where soil+ waste from iron slime plus organic matter were
applied together compared to other treatments. The result suggested that
iron slime has some favourable characteristics for binding organic carbon
in the iron slime matrices in presence of organic matter compared to other
treatments.
5. The result show that the amount of available N,P,K and total N contents
have been found to be increased with the application of organic matter.
The amount of those nutrients were although recorded a higher amount in
soil+ organic matter treatment but the highest value of those nutrients
were recorded with soil+ waste from iron slime + organic matter
treatment. From this study, it has been found that the use of iron slime
mixing with normal soil and organic matter may be beneficial in enhancing
soil fertility and crop production.
6. The results shows that the amount of organic carbon increased when
waste from iron ore slime it amended with organic matter irrespective of
moisture regimes. The magnitude of such increase, however, further
enhanced in iron slime when it is waterlogged after amending with
organic matter.
7. Results show soil and slime (of ratio of 2:1) with recommended dosage of
NPK provides nutrients to rice crop during its growth and this result is
better than soil + recommended dosage of NPK. This supports the role of
waste from iron ore slime as a soil amendment.
8. The results show that the amount of organic carbon content in growing
cabbage has been found to be increased in the highest amount (0.50%)
at 45 days if crop growth treatment where soil : slime mixed in the ratio
of 4:1 along with NPK and FYM. From the results it may be concluded that
mixing of soil with waste from iron slime beneficiation in different ratios
might be useful in augmenting soil nutrient status as well as improvement
of organic carbon content in the amended soil.
9. The changes in exchangeable ammonium content (Table-2d) in soil has
been found to be increased with highest content (411.49 mg/kg) in the
soil: waste from slime mixed in the ratio of 1:1 along with NPK and FYM
which was closely followed by the treatment where soil: waste from slime
mixed in the ratio of 3:1 along with NPK and FYM.
10.The results for the changes in nitrate nitrogen and available N content in
the treated slime are presented in table 18 and 19. The amount of nitrate
N and available N content have been found to be increased highest the
treatment where soil: waste from slime mixed in the ratio of 3:1 along
with NPK and FYM. The overall results suggested that the management of
waste from iron slime through mixing with either 3:1 or 1:1 or 4:1 along
with NPK and FYM might be useful in improving soil fertility and soil health
vis-a-vis growing crops.
11.This process is applicable to all types of waste generated through iron ore
beneficiation as physical and chemical characteristics of these wastes are
identical to waste from iron ore slime beneficiation.
12.This process is applicable to many other crops which are under
investigation through filed study.

ABSTRACT

Present invention is reiated to the development of soil conditioner (amendment)
from waste of iron ore slime beneficiation. The invention further relates to the
development of a new method in making soil amendments from waste of iron
ore beneficiation and thus making iron ore beneficiation a zero waste technology.