Study on Adding Ammonium Hydrogen Fluoride to Improve Manganese Leaching Efficiency of Ammonia Leaching Low-Grade Rhodochrosite

Peng Yang,Xiaoping Liang,Tengfei Cui,Yu Wang,Chengbo Wu

doi:10.3390/met11091496

Abstract

The ammonia leaching method for treating low-grade rhodochrosite has the advantages of a good impurity removal effect and low environmental pollution. In this paper, aiming at the low leaching efficiency of low-grade rhodochrosite treated by the ammonia leaching method, studies on enhancing the leaching efficiency of manganese by using ammonium hydrogen fluoride as an additive are carried out. The effects of different ammonia concentrations, leaching temperatures, leaching times, liquid-solid ratios, stirring rates, and the addition of ammonium hydrogen fluoride on the leaching efficiency of manganese with and without ammonium hydrogen fluoride as an additive were comparatively studied, and the parameters of ammonia concentration, ammonia leaching temperature, and ammonium hydrogen fluoride dosage were optimized in the experimental study. The results indicated that ammonium hydrogen fluoride as an additive in the treatment of low-grade rhodochrosite by the ammonia leaching method could effectively increase the leaching efficiency of manganese, and the optimal process parameters were obtained. Meanwhile, the addition of ammonium hydrogen fluoride didn’t affect the quality of the steamed ammonia product.

Highlights

When there is no ammonium hydrogen fluoride and the addition amount of ammonium hydrogen fluoride is 8%, the ammonia concentration varied from 6 mol/L to 14 mol/L, leaching temperature ranged from 25 ◦ C to 35 ◦ C, leaching time ranged from 0.5 h to 2.5 h, liquid-solid ratio varied from 3:1 to 6:1, and stirring rate varied from 200 r/min to 400 r/min, where five experiments were performed for each factor within the range of variation
Through the single-factor experimental results, the effects of ammonia concentration, leaching temperature, leaching time, liquid-solid ratio, stirring rate, and the amount of ammonium hydrogen fluoride on manganese leaching efficiency were analyzed; the ammonia leaching process was optimized by the response surface method; and the leach solution under the optimal ammonia leaching process was distilled with ammonia to determine whether the addition of ammonium hydrogen fluoride affects the quality of the final manganese product
It can be seen from the figure that with or without the addition of ammonium hydrogen fluoride, the leaching efficiency of manganese always increases with the increase of ammonia concentration

Summary

Introduction

Manganese (Mn) is one of the 12 most abundant elements 0.1% of the earth’s crust), and can be associated in different ways, finding oxides, sulfides, carbonates, and silicates with greater abundance. Some recent studies mention that the largest manganese reserves in the world (high-grade deposits) are found on the seabed [1]. 95% of the manganese produced annually is being consumed by the steel industry, and the remaining 5% is being used by other industries, such as the chemical, paint, fertilizer, and battery industries [2]. Manganese levels in the world range from 20% to 60%, but a significant proportion belongs to the low- and medium-grade (Mn: 20–35%) category [3]. With the depletion of high-grade manganese resources, low-grade manganese is becoming more important

Objectives

Methods

Results

Conclusion