This study discusses the extraction of scandium from bauxite residue as a by-product from an alumina refinery through High-Pressure Acid Leaching (HPAL) in sulfuric acid solution. The high-pressure leaching in sulfuric acid could effectively dissolve scandium, with minimum silica gel formation and relatively lower co-extracted iron …

To extract vanadium in an environment friendly manner, this study focuses on the process of leaching vanadium from vanadium slag by high pressure oxidative acid leaching. Characterizations of the raw slag, mineralogy transformation, and the form of leach residues were made by X-ray diffraction, scanning electron microscopy, and …

In this work, oxygen pressure acid leaching is implemented to augment the leaching efficiency of valuable metals from sintered nickel alloy. Techniques investigation shows that NiO in the sample and NiO coated by Ni 2 O 3 impede the ongoing dissolution of nickel during atmospheric acid leaching. The nickel oxides undergo conversion into …

A total of 98.11% of iron and 99.86% of aluminum can be selectively removed by the high-pressure acid leaching. Some recommendations for improving emission control and …

This paper describes the experimental findings of the extraction of nickel and cobalt by high pressure acid leaching (HPAL) of a refractory limonitic nickel laterite ore from the Gördes region of Manisa in Turkey. By optimizing the basic HPAL process parameters: leaching at 255 °C with 0.30 sulfuric acid to ore weight ratio with a particle ...

@article{Rivera2019SelectiveRE, title={Selective rare earth element extraction using high-pressure acid leaching of slags arising from the smelting of bauxite residue}, author={Rodolfo M. Rivera and Buhle Sinaye Xakalashe and Ghania Ounoughene and Koen Binnemans and Bernd Friedrich and Tom Van Gerven}, …

Extraction of nickel from Western Australian laterite ores via sulphuric acid leaching at 250. °C has been optimised by the addition of sodium sulphate.. Leaching of a nontronitic nickel laterite ore in fresh water, with a sulphuric acid loading of 420 kg/t ore extracted 93% of nickel from the ore.When limonitic nickel laterite ore was leached in …

Before extraction, kaolin was calcined with NaCl at 700 °C for 3 h. The percentage of alumina extracted was 79.3% after leaching in 5.33 M H 2 SO 4 for 3.75 h, at a temperature of 140 °C under reflux conditions. Eventually, Al (OH) 3 was precipitated using CO 2 after the treatment of the leach liquor with NaOH.

The yellow cake product precipitated from alkaline leaching circuits is always of higher grade than the final product obtained from acid leaching. As the operating cost of alkaline leaching is relatively high, this technology is traditionally used for uranium ores of higher grade. Table 2.5 gives comparison of acid and alkaline leaching of uranium.

Hence, high-pressure acid leaching was first used in the Moa plant of Cuba, and the recovery ratio of Ni and Co can reach more than 90% during the treatment of limonite laterite nickel ore. 24 Subsequently, the high-pressure acid leaching was used in the recovery of Ni and Co from RAMU lateritic ore by Shi, 25 and the 96% and 94% …

High-pressure acid leaching (HPAL) and atmospheric acid leaching (AL) are the −. two prevailing technologies for hydrometallurgical processing of laterites [16 − 21]. Although …

Lee et al. examined the extraction of vanadium from stone coal by using the acid leaching method under pressure; It was found that high purity vanadium pentoxide powder is produced under pressure ...

Abstract and Figures. This paper describes the experimental findings of the extraction of nickel and cobalt by high pressure acid leaching (HPAL) of a refractory limonitic nickel laterite ore from ...

HPAL needs an autoclave for high-pressure and temperature leaching reaction, whereas AL can occur at atmospheric pressure. HPAL and Caron processes become less attractive due to high capital expenditure and energy consumption . AL needs high acid consumption and has slower extraction kinetics than HPAL . Hydrochloric …

Currently, reduction roasting ammonia leaching (Caron process) and high pressure sulfuric acid leaching (HPAL) are the mainstream processes for the hydrometallurgical treatment of limonite laterite ore [8], [9]. The main process steps in the Caron process are reduction roasting, atmospheric ammonia leaching, ammonia …

The recovery of rare-earth elements from an alumina and silica rich slag produced during the smelting reduction process of bauxite residue was studied. The slag was leached with sulfuric acid at ...

Phosphoric acid (H 3 PO 4) was proposed to replace sulfuric acid (H 2 SO 4) for the efficient gallium (Ga) leaching from red mud (RM). The effects of different leaching reagents were compared, and the influence of experiment conditions on the leaching was investigated. The results show that H 3 PO 4 has the best leaching effect.

In high pressure acid leaching processes, lateritic nickel ores are interacted with aqueous sulphuric acid solutions in acid resistant autoclaves at temperatures of 230-270 °C and under pressures of 3.3-5.5 MPa for 60-180 minutes. Under these leaching conditions, iron mainly follow a dissolution-precipitation path, forming insoluble solid ...

Preliminary tests over a range of acid additions showed that nickel extraction increased with increasing acid addition, up to a maximum of about 90%, based on the head grade of 0.4% Ni. The residue was not analysed. The pH of the solution, (after cooling) decreased marginally with increasing acid addition, as shown in Fig. 1. No magnesium …

High pressure acid leaching has been extensively used in hydrometallurgical processes because of the high leaching of target metals and excellent filtration performance of the leach slurry (Judd and Wardell, 1988). However, the extraction of Ga and Ge using the pressure acid leaching process was hardly examined. In this …

These results indicate that high-pressure acid leaching gives a high recovery of scandium with higher selectivity to iron and lower acid requirements than direct acid leaching at atmospheric pressure that yields extracted scandium of 80% with an iron co-extraction of about 60% [32]. In addition, the leaching with inorganic acid at …

The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and cobalt. The effects of sulfuric acid added, leaching temperature, leaching time and liquid/solid (L/S) ratio on metals extraction were examined. ... Key words: high …

This study is aimed to assess the potential implementation of High-Pressure Acid Leaching (HPAL). HPAL is a proven technology but not utilized in Indonesia due to the high investment, and it requires a large media for waste disposal. Nickel limonite ore with grade 1.1 – 1.4 % can be processed using HPAL technology to produce more than …

the last decade, high pressure acid leaching (HPAL) in autoclaves has become the technologically preferred method for processing gold present in sulfide minerals. AL autoclaving entails subjecting the acidic ore to temperatures up to HP 250°C with …

The main reactions during the pressure acid leaching process are shown as following [31, 34]: 2Ni + O 2 + 2H 2 SO 4 = 2NiSO 4 + 2H 2 O. 6. ... acidic pressure leaching—solvent extraction separation of copper—high-temperature hydrolysis precipitation removing of iron- selectively precipitated of nickel and cobalt using sodium …

When the direct acid leaching method is adopted, high acid concentration (6 mol/L or higher) is usually needed [16] and other conditions, such as high temperature and high pressure, are also ...

However, harsh operating conditions, including high temperature and high pressure (250-270 • C, [4][5], are required during the process of high pressure acid leaching [14, 15]. If the under the ...

The mechanism of leaching involves acid dissolution of the host mineral lattice followed by hydrolysis and precipitation (transformation) of a variety of insoluble oxides and sulphates of iron, aluminium and silica under the high temperature conditions. Optimum leaching conditions and final liquor composition varies according to the ore mineralogy.

High Pressure Acid Leaching HPAL is the most widely adopted technology for processing lower grade limonite ores, particularly given the Caron process is no longer seen as …

The traditional process has the disadvantages of high acid consumption, high extraction rate of impurities and difficult purification of leach liquor. ... The optimal conditions for nitric acid pressure leaching are as follows: temperature of 200 °C, initial nitric acid concentration of 1 mol/L, liquid-to-solid ratio of 2.5 mL/g, and holding ...

This study is aimed to assess the potential implementation of High-Pressure Acid Leaching (HPAL). HPAL is a proven technology but not utilized in Indonesia due to …

High Pressure Acid Leaching HPAL is the most widely adopted technology for processing lower grade limonite ores, particularly given the Caron process is no longer seen as economic. It represents >10% of global nickel supply and given the growing demand for nickel sulphate (and cobalt), its share is expected to increase in the future.

In essence, HPAL involves sulphuric acid leaching of lateritic ores at temperatures above 240ºC, which can only be achieved at high pressures. The HCE has a dedicated fully equipped pressure leaching facility with a range of bench scale autoclaves including; 2 x 1 Gal Ti2 and 1 x 5 Gal Ti2, plus a 1 Gal Hastelloy batch autoclave.

Therefore, this research aims to develop a copper recovery process from flotation tailings using high‒pressure leaching (HPL) followed by solvent extraction. Over 94.4% copper was dissolved from the sample (CuFeS 2 as main copper mineral) by HPL in a H 2 O media in the presence of pyrite, whereas the iron was co‒dissolved with copper ...

Jul 2020. Srđan Stanković. Srećko Stopić. Miroslav Sokić. Bernd Friedrich. View. Show abstract. PDF | On Sep 4, 2015, Şerif Kaya and others published ERES 2014 - HIGH PRESSURE ACID LEACHING ...

In essence, HPAL involves sulphuric acid leaching of lateritic ores at temperatures above 240ºC, which can only be achieved at high pressures. The HCE has a dedicated fully equipped pressure leaching facility with …