Author	Work done	Results
Haifeng et al. [62]	The reductive leaching of manganese from low grade manganese ore in H₂SO₄ using cane molasses as reductant 12MnO₂ + C₆H₁₂O₆ + 12H₂SO₄ → 12MnSO₄ + 6CO₂ + 18H₂O.	Increase in concentration of cane molasses leads to leach efficiency of manganese and causes the concentration to decrease accordingly.
Pagnanelli et al. [63]	Recovery of zinc and manganese from spent batteries by different leaching system. Sulphuric acid/oxalic acid and sulphuric acid/hydrogen peroxide.	Low zinc content in the range 50 to 120 mg/L was extracted by hydrometallurgical technique.
Hariphrasad et al. [26]	Mn recovery from medium grade ore using a waste cellulosic reductant. 12MnO₂ + (C₆H₁₀O₃)_n・12nH₂SO₄ → 12nMnSO₄ + 6nCO₂ + 17nH₂O.	High % of Mn extraction (93.1%) was obtained under the following conditions: pulp density 10%, time 8 hrs, sulphuric acid 5% (v/v), temperature 90˚C and reductant to ore ratio 0.5.
Baba et al. [65]	Lixiviation of manganiferrous aluminosilicate mineral in hydrochloric acid.	The results showed that the rate increases with hydrogen (H⁺) concentration, reaction temperature but decreases with particle size.
Yuksel et al. [64]	Dissolution kinetic of calcinated manganese ore in acetic acid solutions.	It was observed that the dissolution of calcinated rhodochrosite increased with increasing reaction temperature; stirring speed, reaction time and acid concentration and decreasing particle size and solid to liquid ratio.
Jingjing et al. [54]	Reduction of low grade manganese oxide ore by biomass roasting.	The recovery of manganese can reach over 97% by using sawdust as reductant. The optimal conditions are as follows; particle size (150 µm, Mn/sawdust 5:1, roasting temp. 60˚C for 40 min, H₂SO₄ concentration 1 mol/L and liquid/solid ration 10:1.
Haghsherias et al. [25]	Leaching recovery of zinc, cobalt and manganese from zinc purification residue.	The results show that 50 g/L is a suitable acid concentration for the leaching of the HFC cobalt and manganese residual content. The addition of 5 g/L of H₂O₂ as a reductive agent has the best influence on both the cobalt and manganese leaching process. Greater amount of H₂O₂ do not have a significant effect.
Kono et al. [58]	Separation and recovery of Mn, Cu, Ni and Co from sulphurous acid leach liquor of sea nodules.	In this process, Cu, Ni, Co and Mn were completely leached with 0.2 M H₂SO₃. After oxidation by aeration, Fe²⁺ was precipitated as Fe(OH)₃ at pH 4.3 - 4.4. Subsequently, manganese was precipitated as MnCO₃ by addition of (NH₄)₂ CO₃, while Cu, Ni and Co in the solution were stabilized as ammine complexes with NH₃.
Gega and Walkowlak [68]	Leaching of zinc and manganese from used up zinc-carbon batteries using aqueous sulphuric acid solutions.	The final optimum conditions for leaching process were determined to be 2.0 M sulphuric acid, a process temperature of 60˚C and a solid to liquid ratio of 1:100 under these conditions 100% of zinc and about 50% of manganese could be leached in the time of 1 hour.