Yankuang ceshi (May 2021)
Studies on Analysis Conditions of Specific Surface Area of Polymetallic Nodules
Abstract
BACKGROUND Polymetallic nodules are predominant in deep sea sedimentary mineral resources due to the enrichment of many critical metals. Polymetallic nodules are loose and porous, which is the critical material feature that contributes the adsorption of trace metals from seawater and pore water and then enrichment and mineralization. Therefore, specific surface area (SSA) is one of the key factors for studying the ore-forming process of polymetallic nodules. At present, the methods for SSA determination are well-developed. However, they are less applied in the analysis of the specific surface of polymetallic nodules, and the pretreatment conditions are not constant according to various research targets. OBJECTIVES In order to explore the pretreatment conditions for the BET SSA analysis of polymetallic nodules, and provide necessary parameters for the study of the enrichment of trace metals in polymetallic nodules. METHODS Polymetallic nodules from the Atlantic, Indian, and Pacific oceans were collected. The pretreatment conditions including temperature, duration, and particle size for SSA analysis of polymetallic nodules were studies by applying temperature programming, heating accumulation, and particle size comparing methods. RESULTS The results showed that the analysis values of SSA reached plateau when the heating temperature ranged from 210℃to 350℃. The analysis values of SSA remained constant after heating for 3 hours by a step of 1 hour at 210℃. The SSA values of samples with a size of several millimeters were 1.027-28.535m2/g higher compared with those of the same samples crushed into microns. CONCLUSIONS Reliable SSA values can be obtained when the polymetallic nodules with sizes of several millimeters are heated in a vacuum system for 3 hours at 210℃, which is the pretreatment condition for analyzing SSA of mineralization-related polymetallic nodules.
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