EFFICIENCY OF THE LIQUID HYDROCARBONS USAGE IN THE ENRICHMENT PROCESS OF IRON ORE

EFFICIENCY OF THE LIQUID HYDROCARBONS USAGE IN THE ENRICHMENT PROCESS OF IRON ORE

Scientific article

Shkurenok V.¹, Bakhyt A.², Ostanina N.³, Panova A.⁴

^{1, 2,3,4} Omsk State Technical University, Omsk, Russia

Abstract

This work proposes the liquid hydrocarbon reductant (LHR) usage in the process of iron ore opening-up to a metallurgic range. Calcination process optimization of  Lisakovsk gravity-magnetic concentrate (LGMC) was performed by the planning of experiments using Seidel – Gauss method. Iron content in the concentrate increases from 47,6 % to 54,17 % in optimal conditions.

Key words: iron ore, liquid hydrocarbon reductant, enrichment process

In the context of resources depletion of quality and rich iron ore, metal industry faced the task of involvement in the sphere of production of  large reserves of easily extracted iron oolitic ores. There are more than 16 billion tons of the explored reserves of such ore in Kazakhstan [1]. Lisakovsk ore deposit is used in the technological scale. Lisakovsk iron ore deposit characterized by favorable conditions for open-cast mining is a powerful source of raw materials for the development of the metal industry in Kazakhstan and Russia.

Iron ore of this deposit is characterized by very difficult dressability and low iron content. Iron ore deposits are a mixture of oolitic ore minerals, silica sand and alumina material. Concentrates of such ores contain no more than 50 % of iron (Table 1) and are greatly inferior in quality to iron-ore raw materials obtained from other types of ore, from magnetite quartzite for example. The phosphorus content reaches 0,9 % in the Lisakovsk concentrate. This harmful component lower the quality of the iron concentrates. For this reason huge stocks of similar ores are not too actual in our country or abroad at present.  

Table 1.

LGMC chemical content

Main component content, wt%
Fe	SiO2	Al2O3	P	S	CaO	MgO	SiO2/ Al2O3
47,6	9,64	4,37	0,7	0,013	0,30	0,32	2,21

The most promising option to increase the iron content in Lisakovsk gravity-magnetic concentrate (LGMC) is the conducting of  heat treatment (calcination) of the source of raw materials in the presence of liquid hydrocarbon reductant (LHR). This process promotes a destruction of oolites and a penetration of LHC through microcracks in the mass of ore with magnetizing calcination and selective disengagement of quartz.

The development of the technology of deep magnetic separation concentrates would solve the problem of providing of high-quality iron ore for steel plants in Kazakhstan and Russia. Thus, problem solving of the increasing of the metallurgical value of iron concentrates is the important concern, which allows the metal industry of the country to involve huge raw resources.

In industrial practice solid, gaseous and liquid reducing agents are used in the process of magnetizing calcination of oxidized iron ores. The usage of solid and gaseous reducing agents has several disadvantages (such as the high process temperature, the brevity of contact with the ore, the difficulty of accurate dosing and uniform mixing of reductant with the ore, etc.).

The usage of  LHR admits to reduce the calcination temperature, to improve the process rate (extraction of iron to the concentrate and the quality of the obtained concentrate) and to decrease the consumed reductant by  3 – 5 times.

The research work was conducted by the planning of experiments using Seidel – Gauss method. Arrays of experimental data are processed according to the method described in the book by Professor V.P. Malyshev [2]. A plan of the experiment is drafted at 5 levels for 3-factorial experiment (Table 2). Deal factors were: temperature range (T) 400 – 800 ºC, calcination time (τ) from 30 to 90 minutes, LHR concentration (C) of 0,25 to 1,25%.

Table 2.

Experiment plan

№	Factors
	T, ºC	C (LHR), %	τ, min
1	400	0,75	60
2	500	0,75	60
3	600	0,75	60
4	700	0,75	60
5	800	0,75	60
6	700	0,25	60
7	700	0,50	60
8	700	0,75	60
9	700	1,0	60
10	700	1,25	60
11	700	0,75	30
12	700	0,75	45
13	700	0,75	60
14	700	0,75	75
15	700	0,75	90

Experimental (γ_e) and calculated values (γ_c) of the magnetic fraction yield are presented in Table 3.

Table 3

Experimental and calculated values of the magnetic fraction yield

№	Factors			The magnetic fraction yield
	T, ºC	C (LHR), %	τ, min	γe	γc
1	400	0,75	60	2,2	2,2
2	500	0,75	60	48,2	48,7
3	600	0,75	60	76,5	75,80
4	700	0,75	60	88,0	88,96
5	800	0,75	60	76,6	75,80
6	700	0,25	60	66,21	67,53
7	700	0,50	60	82,89	81,27
8	700	0,75	60	88,08	89,84
9	700	1,0	60	95,19	87,98
10	700	1,25	60	86,67	92,1
11	700	0,75	30	65,33	65,98
12	700	0,75	45	83,91	83,33
13	700	0,75	60	88,97	89,95
14	700	0,75	75	83,91	83,08
15	700	0,75	90	65,33	65,98

The research work identified the optimal conditions: temperature of the reducing calcination – 700 °C, the process time – 60 minutes, the concentration of the liquid hydrocarbon – 0,75 %. The concentrate with iron content  54,17 % was obtained in optimal conditions.

Thus the patterns of parameters change and quality of products depending on the calcinations modes of  LGMC thermochemical treatment are revealed on basis of multivariate experiment. The concentrate was obtained with the following composition (wt%): Fe – 54,17; SiO₂ – 10,97; Р – 0,8; Al₂O₃ – 4,97 at calcination temperature equal to 700 °C, for LGMC treated with 0,75 % solution of LHR.

Thereby the usage of  LHR in the calcination process of iron ores allows to increase iron content in LGMC from 47,6 % to 54,17 %. Subsequent magnetic separation of LGMC can increase the iron content up to 57,7 % that significantly improves the quality of the concentrate.

References in English

1. Kantemirov, B. Levinov, S. Namazbaev. Analysis of the situation and perspectives of enrichment and dephosphorization technology development of iron concentrates of Kazakhstan. – Almaty 13 (2006) 134 – 137.
2. Malyshev. Probabilistic and deterministic planning of experiments. – Almaty: Science (1981) 116.