Materials From Hazardous Iron Ore Treatment Waste, Concrete Demolition Debris And Lime Production Waste to Increase Environmental Sustainability of Industrial Regions

To prevent environment pollution by hazardous industrial dumps of iron ore treatment sludge, concrete production/demolition debris and lime production waste sustainable cement-less construction materials were developed for substitution of traditional natural raw components excavated in careers, irreversibly destroying natural bonds. Their ​​ axial resistance values on the 3rd day of hydration were till 2.34 MPa, on the 28th day - up to 3.94 MPa, on the 180th day 8.40 MPa and on the 365th day 10.22 MPa. The expanding coefficient on the 3rd day were till 2.13%, 2.51% on the 28th day, and on the 365th day 2.22%. Water absorption on the 28th day was 7.17 - 9.32% and decreases to 6.26 - 8.64% on the 90th day. All these characteristics correspond to the Brazilian norms. The physical - chemical processes of materials’ structures formation included alkaline dissociation of solid particles’ surface, with sol appearing and densification till transition to gel. Long-lasting gel compaction and densification to stone-like condition made its structure similar to natural rock materials - silica, opal, obsidian, perlite, pumice, amber, flask, etc. They can be used for production of road bases, concrete blocks and solid unburned bricks, among other sustainable construction materials.

Ore treatment hydrogen peroxide during heap leaching of gold

Over the past century, many problems have been focused on the problems of low leaching rate of gold and methods have been developed to intensify the leaching of gold. Among these methods, the use of hydrogen peroxide to accelerate the leaching of gold is known. In order to intensify the leaching process, the indicators of cyanide leaching of gold from ore using hydrogen peroxide were studied. This article presents the results of assay-gravimetric, chemical, and mineralogical analyses of gold-bearing ore from the Sari Gunay Deposit (Iran). The content of sulfide sulfur ore belongs to the category of low-sulphide, by oxidation of sulphur (50.70%) to the category of oxidized ores. Thermodynamic analysis of possible reactions of ore components with hydrogen peroxide is carried out. Laboratory studies on cyanide leaching of gold have shown that the maximum recovery of gold is 52.92% at a concentration of hydrogen peroxide of 0.5%, the recovery of gold without ore treatment is 52.03%. The results of laboratory and column tests with and without treatment with hydrogen peroxide (H2O2–0.5%) were compared. Treatment of gold-bearing ore with hydrogen peroxide during heap leaching of gold increases gold recovery by 1.2% and amounts to 55.89%, without treatment - 54.69%. This increases the consumption of sodium cyanide by 0.04 kg/t.

Design of the Otjikoto Gold Mill, Namibia

The Otjikoto Gold Mine in the Republic of Namibia is located approximately 300 kilometers north of the capital city of Windhoek. The project features surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and recovery of gold. Initial mill design capacity was 2.5 million tonne per annum but then expanded after 9 months of operation to 3.1 million tonne per annum. The technical steps to establish the Otjikoto mill design from process selection in the due diligence stage, through flowsheet development in the feasibility study followed by detailed engineering design are reviewed in this paper along with mill performance during start-up and in 2019.

INVESTIGATION AND OPTIMIZATION OF A CLOSED CIRCUIT CRUSHING OF COPPERMOLYBDENUM ORE

To control the processes of ore treatment proposed adapted to the conditions of a closed cycle crushing-screening criterion "output productive class -2 + 10 mm", reflecting the effectiveness of all processes. The dependence of the outputs of the individual classes of ore and the proposed optimization criterion parameters of the grinding process shows their relationship with the energy intensity of the process. It is shown that the increase in the load on the screen causes a decrease in the screening efficiency and an increase in the mass fraction of class +2 mm in the circulating ore. Excessive increase in the width of the discharge gap of the crusher causes an increase in the output of the circulating product and an increase in energy consumption. Reducing the discharge gap of less than 7.5 mm leads to an increase in the output of the class - 2 mm. An improved system and algorithm for optical analysis of ore size was proposed and tested. The sensors for controlling the granulometric composition of ore are located above the conveyors for the transportation of over-and under-mortar products of the screening operation. The optical analysis mode provides for the sequential switching on / off of feeding conveyors and crushers, thereby ensuring the flow of the crushed product into the measurement zone from one crusher. The total duration of the analysis of ore from 6 crushers is 12 minutes, which does not affect the final performance of the device of crushing. The application of the developed algorithm can significantly improve the accuracy of the analysis of the size of crushed ore and reduce the power consumption during the processing of ore.

Possibility of implementation of dry technology of gold-bearing ores roughing: case study of “Gurbey” deposit

The aim of the research is to identify the ability/feasibility of dry roughing of ore taking as the example “Gurbey” deposit in Irkutsk Region and to develop a rational scheme for processing ores containing free gold. Studies of the dry processing technology of gold-bearing ore at “Gurbey” deposit with the initial weight of 1,123.8 kg were carried out by semi-industrial plants: the DKD-300 combined shock impact crusher, the CMVU-800 centrifugal mill and the POS-2000 air separator developed by CNMI SD RAS. The sample was subjected to two cycles of crushing and four cycles of grinding followed by pneumatic separation. The circulating load is class +12 mm after the DKD-300 crusher, and for the mill, all screening products are +3 mm, as well as the products of classification -3 + 1 mm of the POS-2000 concentrate. As a result of treatment of the concentration products, 23.93 grams of free gold was recovered (concentration on tables: control, recleaning, concentration of the Mosely minerals by analyzer, magnetic separation, heavy medium separation on bromoform). At the same time, it was established that gold from the ore with initial size of 150 mm can be completely stripped and recovered with the POS-2000 air separator with a particle size of up to 100 microns. At the same time gold extraction into the primary concentrate is up to 60%. Based on the results of the research, a basic scheme for dry roughing of “Gurbey” ore containing “free” native gold was developed using the ore treatment devices: RD-MDV-900, DKD-300 crushers, CMVU-800 centrifugal mill and POS-2000 air separator. The technological scheme is fundamental for gold-bearing ores containing "free" gold of fineness over 100 microns.