Beneficiation of Himmetoǧlu Oil Shale by Flotation as a Solid Fuel Substitute. Part 1. Materials Characteristics and Flotation Behavior

Abstract

In this study, the processing of Himmetoǧlu oil shale from Bolu, Turkey, by flotation techniques was investigated for the possibility of achieving a clean solid-fuel substitute. The surface characteristics and mineral content of Himmetoǧlu oil shale were determined using mineralogical, XRD, and FTIR analysis. The flotation response of the sample was tested with several nonionizing collectors and a variety of ionizing collectors belonging to both cationic and anionic groups. The effects of collector dosage and pulp pH on the effectiveness of flotation were also determined. XRD analysis showed that majority of incombustible matter in the sample was carbonate, silicate, and sulfide minerals. FTIR spectrum exhibited significantly strong absorption bands from the organic and oxygen-rich functional groups, revealing the organic-rich and highly humic character of Himmetoǧlu oil shale. Flotation experiments showed that Himmetoǧlu oil shale had a hydrophillic nature and extremely poor flotability because of its humic character. Effective means of ash rejection with an acceptable extent of combustible recovery was achieved by reverse flotation, where mineral matter was selectively removed by amine acetates through reverse flotation. Among the amine acetates used, the most favorable cleaning was obtained in the presence of Flotigam CA at natural pulp pH, where the ash yield of Himmetoǧlu oil shale was reduced from 34.76 to 23.52% with a high combustible recovery of 83.57%.

Challenges related to flotation cleaning of oil shales. Issues due to compositional and surface features and post-grinding surface behavior

“…All these factors reduce the efficiency and effectiveness of oil shale cleaning using the direct flotation process. The results of such challenges and the insufficient cleaning of oil in some details in the previous studies shales using direct flotation were well expressed in some details in previous studies [4,5].…”

“…2 Issues related to composition and surface characteristics of oil shales Figure 1 and 2 show XRD spectra of a high and low quality oil shale samples from Turkey, respectively [4,5]. The spectra show that oil shales may consist of variety of inorganic minerals, i.e.…”

“…As opposed to many types and particularly low-ranking coals, the organic matter is abundant in oil shales, especially in those with lower quality. The relative abundance of inorganic matter and carbonates is a remarkable challenge in application of flotation as oil shales cleaning [4,5]. In direct flotation, high extent of the inorganic matter in the pulp presents a challenge against the bubble-organic matter interaction.…”

Analysis of applicability of oil shale for in situ conversion

“…A few different approaches to heating subterranean oil shale formations have been suggested by researchers [1][2][3][4][5]. In in situ combustion [1,2], a portion of the deposit is set on fire, and the heat of combustion is transferred from the fire front to the rest of the deposit, causing pyrolysis of the kerogen and release of oil and gas.…”

“…In in situ combustion [1,2], a portion of the deposit is set on fire, and the heat of combustion is transferred from the fire front to the rest of the deposit, causing pyrolysis of the kerogen and release of oil and gas. The main advantages of this technology are that no mining is required and all energy required for retorting is produced by burning a small portion of the oil shale.…”