Gold Determination Problem in Barium Production Waste

The most common method for gold content determination in raw materials is fire assay. An alternative to this method is atomic absorption in a solution obtained by dissolving an initial sample in aqua regia. This study focuses on the sludge of one of the chemical plants, in which the barite concentrate (barium in sulphate form) is fused with calcium chloride at coal presence, and then leached in water. Decomposition of samples in aqua regia followed by atomic absorption analysis, as well as fire assay, showed gold content in the sludge at the level of 1-4 gram per ton. The presence of infusible and chemically resistant compounds in the sludge does not allow to the reliable determination of the gold content. Sintering with sodium peroxide for decomposition of stable compounds at 700 ∘ C, dissolution of sinter in acidic solution, evaporation and fire assay of residue made it possible to establish a reliable concentration of gold in the sludge - 10-20 gram per ton. It was found that a direct determination of gold in acidic sinter leach solution provides inadequate values associated with the influence of the background. Keywords: Gold determination, barium sludge, fire assay, atomic absorption

Gold determination in soil by ICP-MS: comparison of sample pretreatment methods

At present, the direct gold determination in geological samples by inductively coupled plasma mass spectrometry (ICP-MS) is still an arduous challenge due to both spectral and background interferences. It is very important and necessary to study the pretreatment processes; therefore, the polyurethane foam treatment and sample digestion methods are explored and compared here. The experimental results showed that the gold adsorption rate of treated foam was significantly improved as the impurities in the foam were cleaned up, and the potential difference of the liquid membrane was increased. Meanwhile, the combination of the foam enrichment and thiourea desorption achieved the selective adsorption and desorption of gold ions, eliminated the interference of coexisting ions, and perfected the detection limits. Compared with the traditional electric heating plate digestion method, microwave digestion, a closed digestion method, had the advantages of less sample and reagent dosage, short time consumption, high degree of automation, thorough digestion, good security, and environmental friendliness and met the requirements of green chemistry development. The proposed microwave digestion-foam enrichment-thiourea desorption-ICP-MS determination method was applied to the gold test in soil samples of the actual gold mining area. It has the great potential as a routine laboratory procedure.

Development and implementation of X-ray fluorescence technique for gold determination in jewelry alloys at the analytical center of the JSC «Krastsvetmet»

A technique of the X-ray fluorescence analysis (XRF) based on a linear regression providing correlation between the gold content in the sample and radiation intensities of the elements of the analyzed alloy is developed at the analytical center of the JSC «Krastsvetmet» (laboratory of X-ray spectral analysis) to increase the rapidity of gold determination in gold-based alloys. The regression equation chosen by the methods including the influencing factor (contributor) and estimating correlation between the disparities and influencing factor takes into account the effect of such elements as Ag, Cu, Zn, Ni, and Pd on the gold line intensity. Virtual calibration samples (VCS) — the results of the analysis of real samples (X-ray line intensities of elements and gold values obtained by the assay method) taken from electronic database (DB) are used to form a system of linear algebraic equations (SLAE) which is to be solved for determination the desired linear regression coefficients. VCS for which the line intensities of the elements are close to those measured for the analyzed sample are selected from the database using a specific filter: the filter value is determined for each of the elements (metals) in the sample. The developed and integrated into the laboratory information system (LIMS) multi-version software (MVS) for solving SLAE includes several algorithms implemented in various programming languages. The use of the presented methodology significantly reduces the time of analysis. The error of gold determination does not exceed 0.13% which is comparable with that in the assay method.

Comparison of the chemical-analytical and geological Data on gold-bearing intervals of boreholes in limits of the Zygyrkol zone of Tyrnyauz ore field

Проведен сопоставительный анализ документации керна буровых скважин и результатов химикоаналитических определений золота в керновых пробах из рудных интервалов золотоносных скарнов Зыгыркольской зоны. Показано, что содержания золота в рудных интервалах не зависят от типа, форм проявления, количества и состава рудных минералов. Отсутствие связи концентраций золота с сульфидами, магнетитом и гематитом подтвердилось и при исследовании пробпротолочек, составленных из хвостов 50 бороздовых проб, отобранных из рудных интервалов, в которых содержания золота по результатам химического анализа составили от 0,6 до 9,9 г/т. Результаты минералогического анализа шлихов показали крайнюю бедность их рудными минералами. В минералогических пробах руд с максимальными содержаниями золота установлены частицы самородного золота, при полном отсутствии в этих пробах сульфидов и других рудных минералов. Множественная корреляция, выполненная по массиву химикоаналитических данных, полученных по результатам кернового опробования золотоносных скарнов Зыгыркольской рудоносной зоны, показала, что золото достаточно сильно положительно коррелируется только с висмутом. Это соответствует минералогическим данным о наличии ассоциации самородного золота с самородным висмутом, установленной по результатам электронномикроскопических исследований. Установлено также отсутствие значимой корреляции золота и серебра, что может свидетельствовать о разных этапах золотой и серебряной минерализаций. Относительно сильная положительная корреляция серебра со свинцом, сурьмой, цинком, мышьяком, марганцем и оловом свидетельствует о связи этого элемента с проявлениями сульфидной минерализации, содержащими галенит, пираргирит и другие сульфоантимониты, сульфоарсениды и сульфостанаты, а также алабандин. Таким образом, установлено, что золотое оруденение в скарнах Зыгыркольской зоны является монометалльным (чисто золотым), образовавшимся раньше так называемых сопутствующих сульфидных и сульфидномагнетитовых минерализаций Тырныаузского рудного поля The correlative analysis of borehole core documentation and results of gold determination in core samples from ore intervals of gold bearing skarns of the Zygyrkol zone has been carried out. It was shown that gold contents in the ore fntervals does not depend on the type, forms of manifestation, number and composition of ore minerals. Absence of connection of gold concentration with sulphides, magnetite and hematite has been also confirmed at investigation of crush samples, composed of tails of 50 trench samples, taken from ore intervals, in which gold contents by results of chemical analysis made from 0.6 to 9,9 g/t. Results of mineralogical analysis of blacksands have shown their extreme poverty in ore minerals. In the mineralogic samples of ores with maximal gold contents there were established particles of native gold, at full absence of sulphides and other ore minerals in these samples. Plural correlation carried out on the array of chemicalanalytic data, obtained by results of core sampling of goldbearing skarns of the Zygyrkol ore bearing zone, has shown that the gold is sufficiently strong correlated only with bismuth. This corresponds to the mineralogical data about existence of association of native gold with native bismuth, established on results of electronmicroscopic research. There is established also absence of significant correlation of gold and silver, what can testify in favor of different stages of golden and silver mineralizations. Relatively strong positive correlation of silver with lead, antimonium, zinc, arsenic, maqnganese and tin, testify about link of this element with manifestations of sulphide mineralization, containing galenite, pyrargyrite and other sulphoantimonites, sulphoarsenides and sulphostannates, and also alabandite. So it has been stated that golden mineralization in skarns of the Zygyrkol zone is monometallic (pure golden), formed earlier than so called attendant sulphide and sulphidemagnetite mineralizations of the Tyrnyauz ore field

Rapid high-performance sample digestion for ICP determination by ColdBlock™ digestion: part 2: gold determination in geological samples with memory effect elimination

Fast dissolution of gold-containing samples and chemically-based resolution of wash-in, wash-out problems for gold in ICP-based systems.