ХИМИЯ ЖӘНЕ ХИМИЯЛЫҚ ТЕХНОЛОГИЯ БОЙЫНША IX ХАЛЫҚАРАЛЫҚ БІРІМЖАНОВ СЪЕЗІНІҢ ЕҢБЕКТЕРІ
221
Si – O - H в силикатах обеспечивает возможность ионного обмена с катионами,
находящимися в почвенном растворе.
Поэтому, несмотря на то, что
90
Sr внесен в почву исследованного участка СИП в
виде жидкого радиоактивного раствора, благодаря кислотному разложению силикатной и
алюмосиликатной составляющим почвы возникают алюмосиликатные новообразования с
неорганической полимерной цепью, способные прочно фиксировать катионы
90
Sr.
Заключение
Таким образом, проведенный анализ по ступенчатому элюированию образцов почвы
различными растворами, которые оказывают избирательное действие на минеральную и
органическую составляющие почвы, на восстановительную и окислительную фракции
почвы, показал, что водорастворимая и обменная доли
90
Sr не превышают десятых долей
процента. Значительную часть радионуклида содержат минеральные компоненты почвы,
разрушающиеся под действием азотной кислоты и смеси азотной и плавиковой кислот
(так называемые кислотнорастворимая и прочносвязанная геохимические фракции
90
Sr).
Возникновение таких фракций
90
Sr можно объяснить высокотемпературными процессами
спекания продуктов деления с минеральными компонентами почвы во время ядерного
взрыва. Однако, несмотря на жидкофазное распыление
90
Sr в составе радиоактивных
отходов, более 50% этого радионуклида в почве площадки «4а» ассоциированы с
труднорастворимой силикатной минеральной составляющей почвы.
Список литературы
1
IAEA Radiological Conditions at the Semipalatinsk Test Site, Kazakhstan:
Preliminary Assessment and Recommendations for Further Studies // Radiological Assessment
Report Series, International Atomic Energy Agency. - Vienna, 1998.- 43 pp.
2
Семипалатинский полигон: обеспечение общей и радиационной безопасности
ядерных испытаний / Кол. авторов под рук. В.А. Логачева. - М.: 2-я тип. ФУ
Медбиоэкстрем , 1997.- 319 с. илл.
3
Tessier A., Campbell P.G.C. and Bisson M. Sequential extraction procedure for
speciation of particulate trace metals // Analy. Chem. – 1979.- 51(7). – Р. 844-851.
4
Прист Н., Буркитбаев М., Артемьев О., Лукашенко С., Митчелл П., Винтро Л.,
Стрильчук Ю., Куянова Е., Омарова А. Радионуклидное загрязнение почвы северо-
восточной части бывшего Семипалатинского испытательного полигона// Труды
Международной конференции «Радиоэкологическая ситуация в Казахстане» . – Курчатов:
2005.
References
1
IAEA Radiological Conditions at the Semipalatinsk Test Site, Kazakhstan:
Preliminary Assessment and Recommendations for Further Studies // Radiological Assessment
Report Series, International Atomic Energy Agency. - Vienna, 1998.- 43 pp.
2
Semipalatinsk Test Site: providing general and radiation safety of nuclear tests/ V.A.
Logachev at all. – Medbioextrem, 1997.-319p. [Semipalatinskiy polygon: obespecheniye
obcshei i radiacionnoi bezopasnosti yadernyh ispytanii/ Collectiv avtorov pod rukovodstvom
L.A.Logacheva. – M.: 2 tip. Medbioextrem, 1997.-319 s.]
3
Tessier A., Campbell P.G.C. and Bisson M. Sequential extraction procedure for
speciation of particulate trace metals // Analy. Chem. – 1979.- 51(7). – Р. 844-851
4
Priest N., Burkitbayev M., A. Artemiev, Lukashenko S. Mitchell, P., L. Vintro,
Strilchuk Yu, Kuyanova E., A. Omarova. Radionuclide contamination of soil of the north-eastern
part of the former Semipalatinsk test site // Proceedings of the International conference "The
ХИМИЯ ЖӘНЕ ХИМИЯЛЫҚ ТЕХНОЛОГИЯ БОЙЫНША IX ХАЛЫҚАРАЛЫҚ БІРІМЖАНОВ СЪЕЗІНІҢ ЕҢБЕКТЕРІ
222
radioecological situation in Kazakhstan." - Kurchatov: 2005. [Priest N., Burkitbayev M., A.
Artemiev, Lukashenko S. Mitchell, P., L. Vintro, Strilchuk Yu, Kuyanova E., A. Omarova.
Radionuclidnoye zagryazneniye pochvy severo-vostochnoy chasti byvshego Semipalatinskogo
ispytatelnogo poligona// Trudy Mezhdunarodnoi konferencii “Radioecologicheskaya situaciya v
Kazakhstane”. – Kurchatov: 2005]
ХИМИЯ ЖӘНЕ ХИМИЯЛЫҚ ТЕХНОЛОГИЯ БОЙЫНША IX ХАЛЫҚАРАЛЫҚ БІРІМЖАНОВ СЪЕЗІНІҢ ЕҢБЕКТЕРІ
223
УДК 544
Nadirov R.K., Syzdykova L.I., Zhussupova A.K.
al-Farabi Kazakh national university
*Е-mail: nadirov.rashid@gmail.com
Copper extraction from smelter slag by ammonia leaching
In this paper, feasibility of copper slag processing by NH
4
Cl aqueous solution treatment
was investigated. It was found that optimum parameters for copper recovery are follows: initial
- 19.9%, initial
- 160 g/L, leaching time - 4.13 h, solid/liquid ratio - 0.53.
Keywords: Copper slag; Leaching; Ammonium chloride; Optimization
*
Надиров Р.К., Сыздыкова Л.И., Жусупова А.К.
Казахский национальный университет им. аль-Фараби
*Е-mail: nadirov.rashid@gmail.com
Извлечение меди из металлургического шлака аммиачным выщелачиванием
В статье исследована возможность переработки медного шлака раствором NH
4
Cl.
Найдено, что оптимальными параметрами для извлечения меди являются: начальная
концентрация NH
3
– 19.9%, начальная концентрация Cl
-
- 160 г/л, продолжительность
выщелачивания – 4.13 ч, отношение «твердое – жидкость» - 0.53.
Ключевые слова: медный шлак; выщелачивание; хлорид аммония; оптимизация
Надиров Р.К., Сыздыкова Л.И., Жусупова А.К.
әл-Фараби атындағы Қазақ ұлттық университеті
Аммиакты шаймалау арқылы мысты металлургиялық шлактан бөліп алу
Мақалада мысты шлакты NH
4
Cl ерітіндісімен қайта өңдеу мүмкіншілігі зерттелген.
Мысты бөліп алудың оптималды параметрлері анықталды: NH
3
бастапқы
концентрациясы – 19.9%, Cl
-
бастапқы концентрациясы - 160 г/л, шаймалау ұзақтығы –
4,13 сағ, «қатты – сұйық» қатынасы – 0,53.
Түйін сөздер: мысты шлак; шаймалау;аммоний хлориді; оңтайландыру.
Introduction
Slags are a left-over of the pyrometallurgical stages in copper recovery process from
sulfide materials, and mainly consists of oxides of metals and silicone [1]. Numerous
publications have studied the leaching of base metals from slag samples [2-9].
Recently, it was found that ammonia solutions containing ammonium chloride are effective
for the extraction of zinc and copper from technogenic raw materials, containing zinc and copper
oxides [10,11]. Physico-chemical basis and technological principles of copper recovery by
ammonia-ammonium extraction based on the properties of the system H
2
O-NH
3
-NH
4
Cl
ХИМИЯ ЖӘНЕ ХИМИЯЛЫҚ ТЕХНОЛОГИЯ БОЙЫНША IX ХАЛЫҚАРАЛЫҚ БІРІМЖАНОВ СЪЕЗІНІҢ ЕҢБЕКТЕРІ
224
containing zinc and copper ammines, and the phase equilibria liquid - solid, liquid – vapor.
Copper dissolution in aqueous solution of NH
4
OH in the absence (1) and presence (2) of
ions can be described by the following schemes:
CuО + 4NH
3(sol)
+nH
2
O→[Cu(NH
3
)
4
](OH)
2
+ (n-1)H
2
O
(1.1)
CuО + х NH
3
(sol) + 2 NH
4
Cl(sol) → [Cu(NH
3
)
n
]
2+
2Cl
-
+H
2
O
(1.2)
Previously we have reported on the investigation of zinc and copper recovery process from
copper smelter slag of Balkhash copper plant (Kazakhstan) by ammonium chloride treatment
[12]. In present study, to avoid the using of high-temperature processes we focused on
investigating the copper recovery process by ammonia solution treatment of copper smelter
slag. The work is undertaken to investigate the effectiveness of four process variables, namely:
initial concentration of NH
3
, initial concentration of
ions, treatment process duration and
solid/liquid ratio on the copper recovery to solution from copper smelter slag.
Experimental design is widely used for regulation the effects of parameters in many
process. The experiments in present work are planned using central composite rotatable design
to investigate the main effects of each operating factors and the interactions of these variables
and to found the factors combination that give the maximum values of copper recovery.
2. Materials and methods
2.1. Materials
Mineralogical analysis, performed using DRON-3M model X-ray diffractometer, indicated
the presence of the following components in the slag sample: SiO
2
, Fe
2
O
3
, FeO, ZnO, CaO,
MgO, CuS, Cu
5
FeS
4
, CuFeS
2
, ZnS, Al
2
O
3
. Chemical analysis of the slag sample determined by
X-ray fluorescence (Spectroscan) is presented in Table 1.
Table 1 - Chemical analysis of the slag sample
Component (%)
Si
Fe
Zn
Ca
Mg
Cu
S
Al
15.30
36.41
5.92
2.94
0.21
2.20
1.34
0.74
2.2. Slag leaching
2.2.1. Experimental procedures
The slag sample produced by Balkhash copper plant (Kazakhstan) was used for the
experiments. Sample of slag (10 g; -200 mesh) was placed into a glass-stoppered 150-ml flask.
An ammonia solution with desired concentration of NH
4
OH and
ions was prepared by
mixing distilled water and NH
4
Cl to the concentrated ammonia solution.
2.2.2. Experimental design
Central composite rotatable design (CCRD) helps to optimize the process, effected by
number of operating parameters with a minimum numbers of experiments as well as to
determine the relationship between response, that is copper and zinc recovery to solution, and
operating factors. The three steps used in experimental design: statistical design experiments,
estimation of coefficient through a mathematical model and analysis of the model workability
[13]. In present study, four operating parameters were selected as independent variables: initial
concentration of NH
3
(
initial
ions concentration
, leaching time
and
ХИМИЯ ЖӘНЕ ХИМИЯЛЫҚ ТЕХНОЛОГИЯ БОЙЫНША IX ХАЛЫҚАРАЛЫҚ БІРІМЖАНОВ СЪЕЗІНІҢ ЕҢБЕКТЕРІ
225
solid/liquid ratio
The levels and ranges of operating parameters shown in Table 2. The
dependent output response variable was copper and zinc recovery (%).
Table 2 - Independent variables and their levels used for central composite rotatable design
Variables
Symbol Range and levels
-2
-1
0
1
2
Initial concentration of NH
3
(%)
2
10
15
20
25
Initial Cl
-
ions concentration
(g/L)
0
40
80
120
160
leaching time (h)
1
2
3
4
5
Solid/liquid ratio
0.2
0.3
0.4
0.5
0.6
Matrix of CCRD is given in Table 3. According to this table, the design is composed of 2
4
factorial design (runs 1-16), 8 star-points (runs 17-24) and 12 replicates runs (25-36).
The least square method was used to estimate the correlation of the independent variables
and the response as a second-order polynomial equation:
(2.2)
were
was the value for the fixed response at the central point of the experiment;
and
were the linear, quadratic and cross product coefficients, respectively; and ε is the residual
error, estimated by the difference between the predicted and the observed value of response (y).
The dimensionless variables are related to the standardized forms as shown below:
,
,
, Δ
Here
and
, represent the maximum and the minimum level of factor in natural unit.
The coefficients of the fitted equation were obtained from data of Eq.(2.2) as follows:
(2.3)
where B is the column matrix of estimated coefficients;
is the dispersion matrix;
is
the transpose matrix
and is the column matrix of observed values. Three known tests were
used to evaluate the adequacy of the mathematical model, including Student
/
s t-test, R- square
test and Fisher test. «Excel» software used for model coefficients estimation (Eq.(2.2)).
3. Results and Discussion
3.1 Leaching experiments
The model coefficients, obtained from mathematical processing of data, presented in Table
3, and were tested for significance ( t-test), at 5% of significance level and 11 degrees of freedom.
ХИМИЯ ЖӘНЕ ХИМИЯЛЫҚ ТЕХНОЛОГИЯ БОЙЫНША IX ХАЛЫҚАРАЛЫҚ БІРІМЖАНОВ СЪЕЗІНІҢ ЕҢБЕКТЕРІ
226
Test results showed that all individual effects for copper and zinc recovery are significant at 5%
of significance level. Only the interaction (
) for the metal recovery and is not significant.
Table 3 - Experimental design and the results for copper recovery into solution
The second-order response function representing copper and zinc recovery to solution
obtained after realizing 36 experiments and discarding the insignificant effects can be shown in
coded variables as follows:
Run
no.
Coded values of parameters
Copper recovery, %
Observed
Predicted
1
1
-1
-1
-1
-1
22.42
23.20
2
1
1
-1
-1
-1
35.49
36.11
3
1
-1
1
-1
-1
30.11
30.81
4
1
1
1
-1
-1
48.53
48.14
5
1
-1
-1
1
-1
34.48
33.82
6
1
1
-1
1
-1
44.57
44.64
7
1
-1
1
1
-1
37.03
37.79
8
1
1
1
1
-1
53.21
53.04
9
1
-1
-1
-1
1
14.56
14.54
10
1
1
-1
-1
1
20.44
19.90
11
1
-1
1
-1
1
30.67
30.81
12
1
1
1
-1
1
40.12
40.59
13
1
-1
-1
1
1
31.63
32.23
14
1
1
-1
1
1
36.39
35.50
15
1
-1
1
1
1
45.67
44.86
16
1
1
1
1
1
53.12
52.55
17
1
-2
0
0
0
27.64
26.95
18
1
2
0
0
0
46.81
47.56
19
1
0
-2
0
0
20.17
20.24
20
1
0
2
0
0
44.91
44.90
21
1
0
0
-2
0
22.46
21.63
22
1
0
0
2
0
43.32
44.21
23
1
0
0
0
-2
47.38
46.46
24
1
0
0
0
2
36.58
37.32
25
1
0
0
0
0
42.40
41.89
26
1
0
0
0
0
41.78
41.89
27
1
0
0
0
0
41.32
41.89
28
1
0
0
0
0
42.11
41.89
29
1
0
0
0
0
41.91
41.89
30
1
0
0
0
0
41.62
41.89
31
1
0
0
0
0
42.68
41.89
32
1
0
0
0
0
42.30
41.89
33
1
0
0
0
0
41.78
41.89
34
1
0
0
0
0
40.89
41.89
35
1
0
0
0
0
42.13
41.89
36
1
0
0
0
0
41.50
41.89
ХИМИЯ ЖӘНЕ ХИМИЯЛЫҚ ТЕХНОЛОГИЯ БОЙЫНША IX ХАЛЫҚАРАЛЫҚ БІРІМЖАНОВ СЪЕЗІНІҢ ЕҢБЕКТЕРІ
227
Copper
recovery
=
41.895+5.152
+6.165
+5.645
-2.285
+1.106
-0.521
-
1.889
-0.910
+2.165
+1.768
-1.159
-2.331
-2.243
(3.1)
The Fisher
/
s variance ratio test, i.e., F-test, was used for testing of equation reliability. The
tabulated F value for 5% of significance is 2.640. Comparison of calculated and tabulated F
values for the model enables to assume the statistical significance:
Residual variance,
- 0.545
Replication variance,
- 0.248
Estimated F value - 2.198
The
values for Eqs.(3.1, 3.2) were found to be 99.6%, indicating the good agreement
between the experimental and the predicted values of copper recovery.
4. Discussion
4.1 Leaching experiments
As is known, the value and signs of the regression equations coefficients provides insights
the impact of the factors and their interactions on the value of the output parameter. The
coefficients of regression obtained above (Eq. 3.1,3.2), shows that initial concentration of NH
3
,
initial
ions concentration, leaching time and solid/liquid ratio all have an individual effect
on the copper recovery from copper slag to solution during the ammonia-ammonium leaching. It
was of interest to compare the effect of the factors significance for the zinc and copper recovery
to solution, separately. Relatively low coefficient of
in Eq.3.2 indicates that
ions
concentration does not significantly impact on zinc recovery to solution, in comparison with
copper recovery. This fact indicates the prevalence of the reaction (1.1) above reaction (1.2)
during the zinc recovery to solution. In turn, the reaction (1.2) requires to significantly recovery
of copper to solution during leaching.
4.2 Leaching process optimization
Approximation method was used to leaching process optimization [14]. The «EXCEL»
software was applied at calculation process. The corresponding conditions of the best metal
recovery are follows:
= 1.98, corresponding to initial
= 19.9%
= 2.00, corresponding to initial
= 160 g/L
= 1.13, corresponding to leaching time = 4.13 h
= 1.29, corresponding to solid/liquid = 0.53
At this optimal parameters 55.62% total copper recovery was predicted using Eqs.(3.1, 3.2).
Whereas maximum copper recovery to solution, obtained at experimental conditions, was
56.48%.
|