Gravity Concentration Research Articles

Gold-ilmenite deposits of the Sikhote-Alin (Primorye) as promising sources of strategic metals

Placer gold was mined in Primorye long before the arrival of the first Russian explorers from the time of the Bohai kingdom (VIII-X centuries). The centuries-old exploitation of precious metal deposits led to the depletion of their geological reserves, which could not but affect the sharp decline in production volumes. At the same time, there are good reasons to believe that the gold potential of the region is far from being exhausted. We need new approaches to forecasting, prospecting and developing sources of mineral resources. These alternative sources include complex ore-placer occurrences of strategic metals, in which gold is an associated component. For a long time, the strategic metals include solid types of minerals that are essential for national security. Many of them (titanium, platinum group metals, rare and rare earth elements) are present in ores and placers associated with basic and hyperbasites of Primorye. An example of this is the gold-ilmenite placers of the Ariadne massif of ultramafic rocks. The objective of this research was to assess the possibilities of industrial processing of these placers using pyro-hydrometallurgy methods. For this, the foundations of an integrated technology for extracting useful components were developed. At the initial stage, the initial sands underwent gravity concentration followed by separation by electromagnetic separation into magnetic and non-magnetic fractions. Then titanium dioxide was extracted from the magnetic material represented by ilmenite using the sulfate method. At the final stage, the non-magnetic fraction, including the bulk of the gold, served as the feedstock for the action of the leaching solutions. The proposed technical solutions will expand the prospects for the mineral resource base in the south of the Far Eastern region in compliance with the principles of rational nature management and environmental protection.

NCAA Division I American football players with sickle cell trait have altered hematological responses and hydration status

Sickle cell trait (SCT) is a risk factor of collapse and sudden death in athletes. We conducted a longitudinal study to determine the hematological responses and hydration status in NCAA Division I American football players with SCT. The study took place over 2 years with 6 SCT and 6 position-matched controls (CON) in year 1; and 4 SCT and 4 CON in year 2. In year 2, three of the four SCT players were recruited and re-enrolled with new position-matched controls (total sample data = 10 SCT and 10 CON). Blood samples were taken at three visits: pre-camp, post-camp, and post-season to examine hemoglobin variants, complete blood counts, and chemistry panel 26. Hydration status was assessed by measuring body weight change, urine specific gravity, and urine and sweat electrolyte concentrations during the pre-season training camp. All SCT players were confirmed to have SCT (HbS = 37.9 ± 2.4%) and had greater red cell distribution width (RDW) compared to CON across all visits. Serum uric acid was higher in SCT (7.3 ± 1.0 mg/dL) compared to CON (6.1 ± 0.6 mg/dL; p = 0.001). Furthermore, serum creatine kinase levels were greater in SCT (1617.0 ± 1034.8 IU/L) at pre-camp compared to CON (1037.4 ± 602.8 IU/L; p = 0.03). SCT players exhibited lower pre- and post-practice urine electrolytes and urine specific gravity (SCT pre: 1.019 ± 0.005 vs. CON pre: 1.026 ± 0.008 p < 0.001; SCT post: 1.020 ± 0.005 vs. CON post: 1.030 ± 0.008 p < 0.01), whereas sweat sodium concentrations were higher in SCT players (55.4 ± 13.6 mmol/L) compared to CON (45.5 ± 10.6 mmol/L; p < 0.001). Given the evidence, greater uric acid and CPK levels in SCT players compared to CON may be an early indicator of altered kidney function and muscle damage, which could be added into NCAA guidelines for surveillance among SCT players. Consistent education and reinforcement of the importance of adequate fluid balance during exercise are critical for both SCT and CON players.

Year-Round Heap Leaching of Gold in Cryolithozone

The experience of heap leaching (HL) was analyzed in the following cold climate regions: Alaska, Western regions of the United States, Canada, Kazakhstan, and Russia. The disadvantages of the developed domestic mobile units were uncovered, and the potential for creating HL mobile units was assessed to enable a year-round use of the technology, including in the cryolithozone. The results are presented, which were obtained during investigation of the material composition of the study object, i.e., technogenic gold-containing deposits of the Transbaikal region. The main element content of the mineral raw materials of the technogenic deposits was as follows: Au — 0.35 g/m3, Ag — 3.9 g/m3, SiO2 — 69.3 %, Al2O3 — 15.4 %, Fe2O3 — 5.9 %, CaO — 0.21 %, and MgO — 1.15 %. The phase forms of gold included: cyanidable (intergrown) — 2.3 %, “sealed in quartz” — 13.5 %, “enveloped” — 28.6 %, in magnetite — 55.6 %. A continuous process line was developed, which included the following four unit modules: gravity concentration, first stage of leaching (tank leaching), second stage of leaching (heap leaching), and sorption. The layout of the continuous process line (HL option during the period of subzero temperatures) is provided. The optimal values of the main process parameters of gravity concentration, as well as the first and second stages of leaching have been established experimentally. Prior to tank leaching, an active multiple-reagent solution based on sodium chloride, water and ozone compounds was prepared in a sealed electrochemical reactor. The tank was partitioned into three sections, in which the following operations were carried out in series: chemical opening of the gold-containing minerals; chlorine removal from the geomaterial; and tank leaching of gold. The total duration of heap leaching was 365 days, which was achieved by using two technological options: option 1 (195 days) — classic HL method (from early April to mid-October), option 2 (170 days) — heap leaching in stationary concrete cuvettes using engineering solutions during the period of subzero temperatures (from mid-October to the end of March). A schematic layout of the stationary concrete cuvette constructed in a special way and buried within a 5 to 8 m layer of soil above the ground level with shielding of the upper surface of the stack (heat-insulating covering, clay, large pieces of ore, sulfide rocks) is provided. Product solution drainage was used at various heights, and perforated rigid PVC pipes were used for supplying warm air deep inside the material. The recovery of gold from the technogenic raw materials was increased on average by 27.1 % due to a year-round heap leaching with the use of two technological options: 1 — by 28.7 % (from 58.1 to 86.8 %) using a classic HL method, and 2 — by 27.4 % (from 58.1 to 85.5 %) by using HL in stationary concrete cuvettes. It is proposed to utilize the secondary waste of the HL field (total of five types) in the road-building and construction industries.

Recovery of magnetite-hematite concentrate from iron ore tailings

The research is aimed at study of the probable recovery of iron from the tailings of the Olcon mining company located in the north-western Arctic zone of Russia. Material composition of a sample from a tailings dump was analysed. The authors have developed a separation production technology to recover magnetite-hematite concentrate from the tailings. A processing flowsheet includes magnetic separation, milling and gravity concentration methods. The separation technology provides for production of iron ore concentrate with total iron content of 65.9% and recovers 91.0% of magnetite and 80.5% of hematite from the tailings containing 20.4% of total iron. The proposed technology will increase production of the concentrate at a dressing plant and reduce environmental impact.

Effects of cross-sectional geometry on flow characteristics in spiral separators

ABSTRACT As flowing film gravity concentrators, spiral separators are extensively used in the processing of numerous minerals. Appropriate design of their cross-sectional geometries has been known as an effective method to improve the performance of spiral separators. However, limited work has been published on the impact of cross-sectional geometry on flow field characteristics in spiral separators. In this study, the effects of cross-sectional geometries with various parabolic profiles (|x|=m|y| n ) of a spiral separator on the flow film thickness, flow pattern and flow regime were investigated by numerical simulation. The validity of the simulation approach was confirmed by the reasonably good agreement between the predicted and measured flow film thickness in the own laboratory spiral separator. Results have shown that the flow film thickness and the mean primary velocity in the inner and middle troughs are reduced by decreasing downward bevel angle or increasing parabolic index. The dominant region of the secondary flow can be expended inward by increasing the downward bevel angle and decreasing the parabolic index. As the radial position extends inward, a larger downward bevel angle is more conducive to improving the intensity of secondary flow. A wider laminar flow region can be obtained with a smaller downward bevel angle or a larger parabolic index. The flow film thickness has a significant positive correlation with the trough slope in the inner and middle troughs. It is recommended that the matching relationship between material properties and flow field characteristics should be fully considered when selecting the cross-sectional geometry. Thus, this study aids the structural design of the cross-sectional geometries of spiral separators.

Beneficiation and flowsheet development of a low grade iron ore: a case study

.In the present study a detailed characterization followed by beneficiation of low grade iron ore was studied. The Run of Mine (R.O.M) sample assayed 21.91 % Fe, which is very low grade in nature. The impurities are SiO2 26.25%, MgO 20.48%, CaO 5.85%, Al2O3 1.86% and loss on ignition (LOI) 12.71%. A Davis Tube test was performed for the assessment of the separability of magnetic ores by low intensity magnetic separators. The heavy liquid test was carried out to evaluate the possible response of the sample by the gravity concentration technique. The samples were subjected to jigging, dry low intensity magnetic separation (DLIMS) and shaking table tests. Thus a sufficient concentrate could not be obtained in +1 mm by using jigging and DLIMS. The obtained results show that the a high grade iron concentrate (>65% Fe) with lower recoveries was obtained from shaking table tests by using -1 mm fraction. According to the results a flowsheet was developed. From the developed flowsheet, it is possible to obtain pellet grade concentrate with 65.41% Fe, 2.54% SiO2, 2.79% MgO, 0.70% CaO and 0.32% Al2O3. with 21.42% weight recovery. The overall ganguerejection recovery of the circuit is over 95%.

Gravity Concentration in Artisanal Gold Mining

Worldwide there are over 43 million artisanal miners in virtually all developing countries extracting at least 30 different minerals. Gold, due to its increasing value, is the main mineral extracted by at least half of these miners. The large majority use amalgamation either as the final process to extract gold from gravity concentrates or from the whole ore. This latter method has been causing large losses of mercury to the environment and the most relevant world’s mercury pollution. For years, international agencies and researchers have been promoting gravity concentration methods as a way to eventually avoid the use of mercury or to reduce the mass of material to be amalgamated. This article reviews typical gravity concentration methods used by artisanal miners in developing countries, based on numerous field trips of the authors to more than 35 countries where artisanal gold mining is common.

Porównanie różnych metod odzysku metali z odpadowych płytek drukowanych

Szybki rozwój technologii, podwyższenie standardu życia i dostępność na rynku to główne przyczyny szybszego starzenia się urządzeń elektronicznych. Każde urządzenie elektroniczne zawiera płytki drukowane, które są cennym źródłem metalu. W pracy przedstawio-no wyniki wstępnych badań możliwości zastosowania różnych metod przeróbki surowców w recyklingu zużytych obwodów drukowa-nych. W tych wstępnych badaniach wykorzystano wzbogacalnik grawitacyjne (stół wstrząsany i wzbogacalnik spiralny Humphreya), separację elektrostatyczną i separację magnetyczną na mokro, uzyskane wyniki przedstawiono w artykule.

Production of Vanadium Concentrate from a Small-Scale Lead Vanadate Deposit by Gravity Concentration: A Pilot Plant Study

The renewable energy revolution calls for high-performing materials and makes metallic compounds like lithium, cobalt, nickel and vanadium more and more critical. Innovations contribute to inventions and developments like vanadium redox flow batteries for large-scale energy storage systems with numerous technological advantages. Potential shortages of vanadium and its sources will contribute to turbulence in vanadium pricing. Nowadays, main sources and production sites of vanadium are located in Russia, China and South Africa. About 85% of vanadium applications are ferroalloys and high-performance alloys, which make production and price of vanadium dependent on the iron ore market. Partial covering of a potential vanadium demand may be achieved by an exploitation of lead vanadate ore deposits as alternative vanadium source. In the present work, the processing of a lead vanadate ore, mainly containing vanadinite and descloizite was investigated. Based on ore characterizations and preliminary beneficiation tests, a flowsheet was developed to design a small-scale processing plant, including comminution, dewatering and gravity separation. Preliminary laboratory tests and samples from the small-scale processing plant show promising results for the recovery of vanadium in a lead vanadate concentrate with a grade of 12 to 16% V2O5 and a recovery of 68 to 75%.

BEHAVIOUR OF SULFUR, ARSENIC AND ORGANIC CARBON IN A GRAVITY CONCENTRATION OF GOLD FROM REFRACTORY ORE

The results of assay-gravimetric, chemical, mineralogical analyzes of gold ore are presented. According to the content of sulfide sulfur and the degree of oxidation of sulfur gold-bearing ore is assigned to the poor sulfide type of ore in the primary zone. Gold ore refers to refractory carbonaceous arsenic-containing sulfide ores. The gravity concentration of ore was assessed using a laboratory 3-inch Knelson KC-MD3 centrifugal concentrator. According to the results of the GRG test, the total gold extraction was 39.58% with the total concentrate yield of 3.96%. The extraction of gold in the first stage is lower than in the subsequent stages. This indicates the absence of large gold in the ore. The behavior of sulfur and arsenic during gravity concentration is similar to the behavior of gold. These data confirm that the main amount of gold is associated with arsenopyrite (arsenic pyrite) and pyrite. The behavior of organic carbon during gravity is significantly different. Only 3.39% of organic carbon passes into the gravity concentrate from ore, which reduces the persistence of the concentrate. Most of the organic carbon (96.61%) remains in the tails of gravity. The content of components in the total gravity concentrate was: Au 21.63 g/t, S 6.40%, As 0.82%, C(organic) 0.58%. The extraction of the components in the total concentrate is as follows, %: Au 39.58; S 34.52; As 27.27; C(organic) 3.39.

The Effects of Pulp Rheology on Gravity Gold Recovery in Free Milling Gold Ore of the Tarkwaian Systems of Ghana

ABSTRACT Gravity gold characterization provides a comprehensive understanding on the effect of mineralogy, particle size, and liberation on gravity concentrator performance. This is of significant economic importance for gold ores with a high amount of coarse gold particles. In this study, the effect of pulp rheology on gravity recoverable gold (GRG) was investigated using a single-stage GRG test on paleoplacer gold deposits of the Tarkwaian system of Ghana. The elemental and mineralogical composition of the gold ore was characterized using ICP-MS, XRD, and QEMSCAN analyses. Bench-scale gravity concentration was performed on the gold ore at varying clay contents (in the range of 5–30 wt.%) using Lab Knelson concentrator in the absence and presence of NaOH (2.5 kg/t) and CaO (2.5 kg/t). The mineralogical analysis showed the ore is oxidized and comprised 88% Quartz, 8% muscovite mica, 2% hematite, and 2% kaolinite. Liberation and association analyses showed 58% of the gold particles were liberated, 1% formed binary with quartz, and 41% formed complex aggregates with other mineral phases. The gravity concentration of the ore without clay material yielded 51% Au recovery (11.2 g/t) at the grind size of 80% passing 106 µm. Partial replacement of the ore with clay material at 5%, 10%, 15%, 20%, and 30% decreased gold recovery from 51% to 25.7%, 12.7%, 8.8%, 5.1%, and 1.5%, respectively. Subsequent conditioning of the slurry with NaOH improved gold recovery due to possible improvement in slurry rheology. However, the addition of CaO decreased gold recovery due to an increase in slurry viscosity.

A Process Mineralogical Evaluation of Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa

A process mineralogical study based on three texturally and mineralogically different chromite-bearing ore types at the Nkomati nickel mine was undertaken, with focus on chromite. Chromite is a by-product of the Ni-Cu-Co-PGE ore at Nkomati Nickel mine. These being the PCMZ_MG (medium-grade Ni-Cu sulphide silicate ore with disseminated chromite), PCMZ_HG (high-grade Ni-Cu sulphide silicate ore containing disseminated chromite) and MCHR (massive chromite unit) ore types. These were processed using benchtop flotation followed by gravity concentration using a shaking table at different grind sizes. Quantitative mineralogical data was obtained using a 600F Mineral Liberation Analyser for the unprocessed and processed ores at three selected target grinds. The Mineral Liberation Analyser data indicated that increased milling does not relate to increased chromite grades and recoveries, particularly for the disseminated PCMZ type ores based on laboratory-scale gravity concentration. The recovery is controlled largely by the chromite chemistry. The results also showed that the MCHR samples that underwent a pre-flotation stage before gravity separation had better Cr2O3 grades (45% to 47%) and recoveries (52% to 61%) than MCHR ore that did not undergo a pre-flotation stage, which recorded grades ranging from 44% to 46% and recoveries ranging from 43% to 60%. This holds promise for the blending of MCHR ores with the PCMZ ores. The PCMZ ores also displayed better Cr2O3 grades and recoveries at coarser grinds. The optimal target grind to process all three ore types is a P80 of 75 μm, which is the current grind size employed at Nkomati Nickel mine. Due to the low nickel price and grade the Nkomati Nickel mine is currently under care and maintenance.

Processing of Low-Grade Chromite Ore for Ferroalloy Production: A Case Study from Ghutrigaon, Odisha, India

The low-grade siliceous chromite ore from Ghutrigaon, Odisha, India, containing ~ 16% Cr2O3, with Cr/Fe ratio of 1.97 and ~ 55% of SiO2, does not find any use in metallurgical industry and hence considered as waste. Mineralogical investigation indicates the presence of chromite and quartz as major minerals with minor fuchsite and kaolinite. The beneficiation studies reveal that the product can be enriched to a Cr/Fe ratio of 3.35 and 3.02 by gravity concentration (wet shaking table) and wet high intensity magnetic separation, respectively. Tiny Cr-grains within quartz and fine silica dusts within chromite inhibit liberation of chromite resulting in poor response to physical beneficiation. As an alternative, processing of ore through pyro-metallurgical route was evaluated. Chromite fines mixed with carbon and lime in the form of pellets/granules was charged to a plasma reactor. In about ten minutes, the metal globules/prills were separated from the slag in 1:6 ratio. The metal, examined through XRD and optical microscope, was found to be ferrochrome alloy. In situ EDAX analysis indicated the metal to have 61.51% Cr, 26.52% Fe and 13.1% C with minor silica (2.42%), and the slag was composed of Ca2Al2SiO7 which revealed that both metal and slag so obtained could suitably be used in different industries.

KajianTeknis Pengaruh Panjang Pukulan Terhadap Recovery Pencucian Bijih Timah Menggunakan Alat Pan American Jig Skala Laboratorium Jurusan Teknik Pertambangan Universitas Bangka Belitung

Washing stage of tin ore is done the separation process valuable minerals of tin ore with mineral impurities. This process can be done using jig such as Pan American Jig. The length of stroke is one of the parameters that affect the performance of the jig with high recovery of tin ore leaching. The experiment was carried out by washing experiment using Pan American Jig scale laboratory on 6 times including variation of stroke length 15 mm, 12 mm, 10 mm, 8 mm, 6 mm, and 5 mm with 19 washing sample. The collection and processing of data includes the weight and grade in each of the feed, concentrates and tailings. Determination of recovery value of each experiment is done through calculation between the grade and weight produced by each sample from washing process. Minerals with a high CC value will be very easily separated by the method of Gravity Concentration for example mineral cassiterite with quartz. The highest recovery was obtained in experiment 1 of 68.848% with a stroke length of 15 mm and the lowest recovery was in experiment 6 of 45.801%. However, the highest grade gain was in experiment 6 of 1.3246% and the lowest grade in experiment 1 was 1.2438%. The higher stroke length made greater recovery value produced, the greater recovery made the lower grade obtained.

The Use of Process Analysis and Simulation to Identify Paths to Improve the Operation of an Iron Ore Gravity Concentration Circuit

The processing of iron ore to recover the valuable iron oxide minerals is commonly carried out using spiral concentrators that separate valuable minerals from non-valuable ones on the basis of the specific gravity of minerals. This paper shows that the analysis of the operation of spirals should not only focus on the minerals (as it is usually the case), but should also consider the particle size of these minerals. Indeed, the sampling of two industrial iron ore circuits and the data processing of the resulting measurements show that unexpectedly about 10% of the coarse heavy iron oxide minerals are not recovered by the spirals of the two circuits. Tests conducted by an independent research center confirm this plant observation. The pilot plant tests also show that the wash water flowrate addition may adversely affect the recovery of coarse heavy mineral particles. A mathematical model for the spiral was implemented into a simulator for an iron ore gravity concentration circuit. The simulator shows a potential 0.7% increase of iron recovery by simply changing the strategy used to distribute the wash water between the rougher and the cleaner/recleaner spirals of the circuit. The simulator also shows that the introduction of a hydraulic classifier into the gravity concentration circuit yields a marginal improvement to the performances of the circuit.

Лабораторные исследования гравитационной обогатимости угля Татауровского месторождения

Лабораторные исследования гравитационной обогатимости угля Татауровского месторождения

Process optimization of a chrome ore gravity concentration plant for sustainable development

Process optimization of a chrome ore gravity concentration plant for sustainable development

Cleaner approach to the recycling of metals in waste printed circuit boards by magnetic and gravity separation

A physical cleaning approach utilizing magnetic separation and gravity beneficiation was used to recover metals from waste printed circuit boards (WPCBs). In addition, particle shape and settling velocity were measured to identify the sorting process. Based on element content analysis, separation procedures were designed for 1–0.5 mm and −0.5 mm. For −0.5 mm particles, magnetic particles were first recovered using a magnetic separator, and separation tailings were re-separated by gravity concentrator. Meanwhile, the 1–0.5 mm was directly separated by gravity separator. For −0.5 mm, magnetic concentrate with yield of 2% and 88% iron grade (oxide) was obtained. The contents of Cu and Fe in the gravity concentrate are 11.09% and 39.62%, with the recovery of 82.33% and 74.15%, respectively. For 1–0.5 mm, Cu and Fe content in concentrate are 67.7% and 8.17%, corresponding to respective recovery of 79.22% and 90.44%. The sorting mechanism was revealed by the particle settling velocity observation. Results show that the settling velocity of metal particles is significantly greater than that of impurity particles for both 1–0.5 mm and −0.5 mm. Because the separation tailings of 1–0.5 mm and the separation concentrates of −0.5 mm have the same settling speed, it is necessary to separate 1–0.5 mm and −0.5 mm particles separately. The study illustrates that the pollution-free physical method is efficient for recycling and recovering metal from WPCBs.

Physical separation methods, Part 1: A Review

Herein, the importance of physical separation methods of ores in mineral processing is widely acknowledged. Of interest is the magnetic separation, gravity concentration and sensor-based separation methods. The process of separating elements of value from gangue in ores depends on its chemical nature and mineralogical attributes hence the need for a profound characterization prior to physical separation. Some ores especially copper sulphides are readily available in nature in low grades usually less < 1% while some may appear relatively in small isolated deposits (Baba et al, 2012). Therefore, it is costly to extract a small portion of a purified metal from such ores. To circumvent high energy and costs when conducting relevant extraction operations, ores directly from mines can be processed physically before smelting, leaching, purifying or other recovery processes. Most physical separation plants and processes are adjunct to the mines to avoid transportation of a heavy ore with only a small portion of valuables. The aim of this review is to present an understanding on physical separation methods with emphasis on how they take advantage of ore physical properties to achieve separation. In addition, developments of these methods with growing technology is also presented.

Pengaruh Riffles dan Kemiringan Underflow Sluice Box Terhadap Optimalisasi Pemisahan Bijih Timah Skala Laboratorium

Underflow sluice box is a mineral processing tool that aims to separate the main minerals from associated minerals based on the principle of gravity concentration, which is equipped with boil boxes and underflow riffles as a separation medium in tin ore. The use of laboratory scale underflow sluice box provides Sn concentrate results with high Sn grade and recovery through the influence of underflow riffles and slope positions. Where underflow riffles parameters are in the position of 0.5 cm, 1 cm and 1.5 cm and the slope used is 0 °, 3 ° and 5 °, the experiment is carried out 9 times using 2 kg feed and the same Sn grade in each sample. From the results of the experiment obtained the dry weight and Sn grade concentrates which were analyzed by Sn grade using Grain Counting Analysis (GCA) and recovery calculations. After analysis and calculation, the highest Sn grade was found in sample 9 with underflow riffles position of 1.5 cm, slope of 5 ° and water flow velocity in the water flow velocity at 54 l/minute at 44.61 %, while recovery was highest in sample 3 with underflow riffles 1.5 cm, slope of 0 ° and water flow velocity in the water discharge at 54 l/minute at 99.13 %. Based on these results it can be said that if the underflow riffles and slope position is greater, the recovery and Sn grade concentrates are obtained high and if the underflow riffles and slope positions are smaller, the recovery is high with a low Sn grade concentrates.