Exploring potential opportunities for the efficient development of the cobalt industry in China by quantitatively tracking cobalt flows during the entire life cycle from 2000 to 2021.

Owing to its key role in high-tech industry and clean energy technology, cobalt has been regarded as a critical material in many countries. In this paper, material flow analysis was used to quantitatively track cobalt material flows in China throughout the entire life cycle from 2000 to 2021. Based on data pertaining to cobalt commodity trade, cobalt loss during raw material processing, and recovered cobalt, we analysed the actual cobalt consumption in China. During the study period from 2000 to 2021, the main findings were as follows: (1) China's cobalt raw material imports accounted for 84.7% of the total raw materials acquired, while the export of cobalt-containing end products amounted to 32.6% of the total production. (2) China's cumulative net import of all cobalt commodities reached 561 kt, and battery products accounted for 73.3% of the total cobalt consumption. (3) China recovered 77 kt of cobalt from end-of-life products, while 327 kt of cobalt was not recovered. (4) The cumulative cobalt loss during raw material processing reached 288 kt, with the highest loss occurring in refining (51.0%), followed by manufacturing and fabrication (26.5%), beneficiation (12.3%), and ore mining (10.2%). The overall utilization efficiency of cobalt was 73.8% throughout the entire life cycle. (5) China's actual cobalt consumption reached 497 kt, accounting for 51.9% of the apparent cobalt consumption. Moreover, 61.1% of the cobalt products produced in China was consumed domestically, while 38.9% was exported. The massive export of cobalt commodities resulted in China bearing a disproportionate responsibility for carbon emission reduction. The research results can provide a scientific reference for the reasonable adjustment of the trade structure of cobalt commodities and realization of the economic and efficient utilization of cobalt resources in China.

A High-Temperature, Low-Noise Readout ASIC for MEMS-Based Accelerometers.

This paper presents the development and measurement results of a complementary metal oxide semiconductor (CMOS) readout application -specific integrated circuit (ASIC) for bulk-silicon microelectromechanical system (MEMS) accelerometers. The proposed ASIC converts the capacitance difference of the MEMS sensor into an analog voltage signal and outputs the analog signal with a buffer. The ASIC includes a switched-capacitor analog front-end (AFE) circuit, a low-noise voltage reference generator, and a multi-phase clock generator. The correlated double sampling technique was used in the AFE circuits to minimize the low-frequency noise of the ASIC. A programmable capacitor array was implemented to compensate for the capacitance offset of the MEMS sensor. The ASIC was developed with a 0.18 µm CMOS process. The test results show that the output noise floor of the low-noise amplifier was -150 dBV/√Hz at 100 Hz and 175 °C, and the sensitivity of the AFE was 750 mV/pF at 175 °C. The output noise floor of the voltage reference at 175 °C was -133 dBV/√Hz at 10 Hz and -152 dBV/√Hz at 100 Hz.

Insights into the evolution of cobalt use and implications through dynamic analysis of cobalt flows and stocks and the recycling potential of cobalt from urban mines in China during 2000-2021.

Several countries regard cobalt as a critical material due to its extensive use in clean energy technology and high-tech industries. To comprehensively examine how China's cobalt industry developed and evolved from 2000 to 2021, our study quantified cobalt flows, stocks and the recycling potential of cobalt from China's urban cobalt mines using dynamic material flow analysis. In 2021, China's in-use cobalt stocks for cobalt-containing end products reached 131 kt, of which battery products and superalloys accounted for 83.8% and 8.1%, respectively. The theoretical cumulative recycling potential of cobalt from China's urban cobalt mines reached 204-356 kt between 2000 and 2021 under different scenarios. However, the actual cumulative exploitation of cobalt from urban cobalt mines was 46-80 kt, of which consumer electronics, cemented carbides, and superalloys were the main recycled products. The cumulative exports and imports of cobalt in all commodities reached 558 and 1117 kt, respectively. China exported a large quantity of cobalt chemicals, chemical derivatives and cobalt-containing end products produced from imported cobalt raw materials. China imported 84.7% of the cobalt raw materials consumed domestically, and 32.6% of the domestically produced cobalt-containing end products were exported. Over the entire life cycle of cobalt, cobalt losses totaled 288 kt, with 51.0% of losses coming from refining, and a 73.8% cobalt utilization efficiency was achieved. China recovered 76.7 kt of cobalt, and the recycling rate of cobalt from end-of-life cobalt-containing end products reached 20.0%. The findings can serve as a scientific basis for China's cobalt industry to develop efficiently and economically.

Modeling the impact of nickel recycling from batteries on nickel demand during vehicle electrification in China from 2010 to 2050.

China is promoting the production and use of electric vehicles (EVs) to achieve carbon neutrality. However, the shift will drive higher demand and tighter supply of nickel in China. We develop a stock-driven bottom-up dynamic substance flow analysis (SFA) model to simulate the demand trends of various EVs under 3 scenarios, the flow of nickel under 9 scenarios and the amount of recoverable nickel under 27 scenarios in China's EV industry from 2010 to 2050. The results indicate that China's current production capacity and primary reserves of nickel cannot meet the growing nickel demand, especially under the High EVs-LNCT scenarios, and closed-loop nickel recovery from EV batteries can effectively alleviate the demand-supply contradiction. In different scenarios, the annual recycling nickel could cover between 67.7 % and 96.6 % of the demand for EV batteries in 2050, and between 37.9 % and 58.1 % in terms of the cumulative quantity by 2050. When the low nickel battery technology is adopted and the recovery efficiency is rapidly improved, the recovered nickel would meet the demand for EV batteries to the highest degree. Therefore, sufficient attention should be paid to low-nickel battery technology and efficient recycling of spent EV batteries, which is of great significance to ensure the development of EV industry and the availability of nickel in China.

Potential impact of the end-of-life batteries recycling of electric vehicles on lithium demand in China: 2010-2050.

China is expected to realise the complete electrification of traditional internal combustion engine vehicles (ICEVs) by 2050. The rapid development of electric vehicles (EVs) has led to the continuous growth of traction lithium-ion battery (LIB) demand, leading to an increase in demand for specific lithium materials. Therefore, end-of-life (EoL) LIB recycling will largely determine the future lithium availability in China. However, the contribution of recovered lithium to lithium availability is unclear, as the possibility of recovering lithium for reuse in traction LIBs manufacturing is uncertain. To analyse the influence of recovered lithium quality on future lithium availability, we evaluated the potential impact of EoL LIB recycling on lithium demand in China. The results indicated that if new LIB manufacturing cannot use the recovered lithium; the secondary resources would soon exceed the needs of the basic demand (BD) field. In the optimistic scenario, when a LiS battery is used, the oversupply could reach 2.33 Mt by 2050 with a recovery rate of 80%, which is equivalent to 44.05% of China's current lithium reserves of 5.29 Mt. Additionally, when the NCM-G battery is used, the total lithium demand would reach approximately 5.67 Mt in 2031, exceeding China's current lithium reserves. In contrast, if the recovered lithium could be reused in new LIB manufacturing, regardless of the type of LIBs used, the recovered lithium would meet approximately 60% (pessimistic scenario), 53% (neutral scenario), and 49% (optimistic scenario) of the lithium demand for LIBs produced with a recovery rate of 80% by 2050. Consequently, the quality of recovered lithium is very important for its reuse, and it is necessary to develop closed-loop recycling with economic benefits vigorously by improving the quality of recovered lithium. Moreover, much work should be done in recycling infrastructure and industrial policies to promote EoL battery recycling.

Pollution, sources and environmental risk assessment of heavy metals in the surface AMD water, sediments and surface soils around unexploited Rona Cu deposit, Tibet, China.

The pollution by heavy metals (HMs) of mining is a widespread problem in the world. However, the pollution by HMs around unexploited deposits (virgin fields) has been studied rarely, especially in Tibet, China. Water, sediments and surface soils were collected to investigate the concentrations of HMs around unexploited Rona Cu deposit in Tibet, China. Furthermore, geochemical fractions of these elements were also analyzed. Pollution and environmental risk introduced by HMs accumulation were assessed using pollution indices, geo-accumulation (Igeo), potential ecological risk index and risk assessment code (RAC). Results indicated that the pH values of Rona tributary river ranged from 2.70 to 3.08, and the average concentrations of Cu and Zn were 2114.00 ± 65.89 and 1402.14 ± 27.36 µg L-1, respectively, exceeding their standard limits. The concentrations (mg kg-1) of Cu, Zn and As ranged in 19.01-1763.10, 62.00-543.06 and 11.12-61.78 for sediments, respectively, and 154.60-1489.35, 55.38-344.74 and 10.05-404.03 for surface soils, respectively, exceeding their standard limits. According to RAC, almost all Cu, Zn and As near low risk status. However, Cd ranged from medium to very high risk in sediments, and low to high risk in surface soils. Statistical analysis suggested that Cu, Pb, Zn, As and Cd in sediments and surface soils may mainly derive from Rona deposit, whereas Cr and Hg may primarily originate from lithogenic sources. The results indicated that very high concentrations of HMs could be occurred in surface water, sediments and surface soils around unexploited deposits. Especially at high-altitude Tibet, the high environmental risk of HMs deserves more attention.