Перколяционное выщелачивание окисленных никелевых руд (стр. 3 )

In our opinion the most promising of the currently known methods, heap leaching is oxidized nickel ores of getting besiality solutions and their further processing to produce nickel products.

In the article, the mechanism of heap leaching of oxidized nickel ore Serov field, studied the influence of the density of irrigation, concentration of acid and the pause between irrigations for leaching and the optimum modes for the stages to 10%, 20-30% and 50% of extraction of nickel.

Introduction

The share of oxidized nickel ores in Russia accounted for more than 9% of the proven reserves of nickel. Deposits of oxidized nickel ores (ONO) located mainly in the territories of Sverdlovsk, Chelyabinsk and Orenburg regions where the group is the metallogenic zones of the Eastern Urals, where the localized Nickel-cobalt deposits of silicate geological-industrial type[1]. The largest of them Buruktalsky (5.5% of nickel reserves), Serov (1.7% of reserves) and Orsk-Khalilovsk. Only in the Urals known 84 deposits with resources of 6.9 million tonnes of nickel[2].

Deposits of oxidized nickel ores are characterized by the complexity of the composition and the complete absence of inclusions of a nickel silicate in the ore pieces, which can be explained primarily by the formation mechanism of oxidized nickel ores are products of weathered ultramafic rocks, consisting mainly of magnesium hydrosilicates, iron and nickel [3].

It should also be noted that in the Urals region explored, but not exploited at present, a lot of small fields with reserves of 10 to 100 thousand tons of ore and low contents of nickel (less than 1%). The commissioning of these fields, will further expand the mineral resource base of Nickel ores is not less than in 2 times, and in the processing of off-balance ores of the producing fields (with content less than 0.5% Ni ) 3 times. Off-balance ore with a nickel content of less than 0.5% are not taken into account when forecasting resources of Nickel [4].

At the moment, the main methods of processing of oxidized nickel ores are pyrometallurgical and hydrometallurgical methods. Hydrometallurgical method is currently processing 35-40% of oxidized nickel ores mainly on plants in Cuba, Australia, China.

The advantages of hydrometallurgy include, first of all, reduce environmental pollution, improve working conditions, possibility of automation of technological operations along with lower energy intensity. All of the above provides hydrometallurgical processes broad prospects for further developments [1].

In recent decades widespread in the world received ammonium carbonate diagram of ore processing (Nicaro (Cuba), Moa Bay (Australia)), including reductive roasting of the ore followed by leaching of ammonium carbonate solution and recovering nickel sulfide and acidic scheme (Murrin Murrin, Cawse (Australia)) , including autoclave leaching the ore with an aqueous solution of sulfuric acid solutions and subsequent precipitation of nickel and cobalt from them [5].

Conducting research such methods like bioleaching of nickel from ores [6] and the extraction of nickel from plants Alusium Murale [7].

Extraction of Nickel from plants Alusium Murale involves the processing of collected during flowering plants with sulfuric acid, followed by extraction of nickel and cobalt from solution using CYANEX 272 .

However, all the methods described are complex and costly. Need to find the most cheap and simple method of extraction of nickel from oxidized nickel ores.

Of the many known industrial methods of processing of oxidized nickel ores is one of the most sustainable and promising way in our opinion is heap leaching. Simulation of heap leaching process is a laboratory percolation leaching.

Experimental

The essence of the process consists in treating the o aqueous solutions of H2SO4, which allows to extract from a piece of ore valuable components (mainly nickel and cobalt), leaving waste rock in the dump.

Conducted research on percolation leaching of oxidized nickel ore Serov deposits. This type of ore belongs to serpentine-buffy-schamozytoviy type and is characterized by complexity and heterogeneity in content of nickel and cobalt, as well as the complete absence of inclusions of a nickel silicate in the ore piece [3]. Nickel in the proximity of ionic radii, probably isomorphically substitutes for magnesium and iron in antigorite, lizardite and clinochlore, which makes it impossible for the enrichment of the ore (table.1). In tables 2, 3 and 4 presents the chemical, granulometric and mineralogical composition of magnesia ore, processing of which is difficult according to the existing in the Urals, technology sliderule melting.

Тable 1 - Ionic radii.

Elements	Fe2+	Ni2+	Co2+	Mg2+
Radius, А	0,75(0,67-Fe3+)	0,78	0,82	0,65

Table 2-Chemical composition of oxidized nickel ores, mass. %

Ni	Co	Mg	Cu	Al	Si	Feобщ	Mn	S
1,19	0,039	18,9	0,012	3,05	17,39	14,83	0,57	0,13

  Table 3-particle size distribution of the sample of oxidized nickel ore.

Fraction, mm	%
−21,5 +10	36,12
-10 +5	20,97
−5 +2	15,67
−2+0	27,24

Таблица 4-Фазовый состав ОНР (масс. %)

Quartz б-SiO2	Goethite FeO	Antigorite  Mg3-x [Si2O5](OH)4-2x	Talc Mg3Si4O10(OH)2	Tremolite Ca2Mg5Si8O22(OH)2	Clinochlore Mg4,882 Fe0,22Al1,881Si2,96O10(OH)8	Lizardite (Mg, AL)3((Si, Fe)2O5)(OH)4
12,4	1,5	36,1	16,9	6,4	10	16,7

Phase analysis of the ore is set on the x-ray diffractometer Bruker AXS.

Leaching was carried out in percolators ore weighing 7.5 kg each at T=20-25oC. Changed the modes of leaching on the concentration of H2SO4, the volume of the feed solution (irrigation density), the number of revolutions of head of solutions at different intervals between irrigations (table.5).

In the first stage neutralization for active compounds kislotoupornymi ore was treated with strong solutions of H2SO4 concentration (pH=0,5-0,8), with a density of irrigation of 140 dm3 solution per 1 tonne of ore (140 cm3/kg) and the interval between irrigations 3 days.

Obtained after irrigation solutions were reinforced to the initial concentration of H2SO4 and sent again for irrigation, i. e. in circulation, to increase the content of nickel. After 28 rpm at pH=1 the solutions contained, g/dm3: Ni 0,850, 0,042 Co, of 8.15 Mg, of 9.27 Fe and Mn 1,150.

Table 5 - Details of the percolation leaching.

№ stage	Num. of circulations solutions	pH initial	pH final	The pause between irrigations, days	Concentraion, g/dm3 .	Extraction, %
Ni	Co	Fe	Mg	Mn	Al
1	28	0,5-0,8	1	3	0,850	0,042	9,270	8,150	1,150	1,920
2	3	1	2	3	2,400	0,127	1,930	21,230	3,140	-
3	14	1	3	2	8,000	0,390	0,010	29,800	7,060	5,070
4	3	1	3	3	2,720	0,126	0,011	-	--	-	10
5	10	1	3,21	2	2,260	0,101	0,010	-	2,810	-
6	12	1	2,7	2	1,58	0,046	0,001	13,39	1,6	2,07
7	10	1	3,3	3	2,160	0,090	0,017.	17,100	2,430	4,170	19
8	8	1,5	3,25	3	2,820	0,078;	0,004	11,870	3,510	5,570
9	3	1,5	3	7	1,660	0,063	0,008	14,120	1,960	3,460
10	3	1,5	3	3	1,180	0,141	0,019	-	0,866
11	15	1,5	3	1	0,95	0,018	0,007	2,6	0,95	0,068	30
12	10	1,5	2,5	1	1,3	0,07	0,096	9,27	1,2	5,32
13	25	0,8	2,6	1	2,32	0,098	0,6	13,64	1,58	8,9	45
14	50	1	2,7	1	0,54	0,019	0,01	4,5	0,29	0,68
15-16	10	0,98	2,5	1	0,88	0,03	0,041	7,16	0,45	1,54	55
17-30	30	1	2,7	4	0,95	0,043	0,1	9,9	0,25	2,48	62

In the second stage, the ore leach at pH=1 with three revolutions of the head solutions. In solutions of the nickel content is increased to 2.4 g/dm3, the content of iron decreased to 1.93 g/dm3. It should be noted that table 5 shows the most typical solutions.