Particle size, chord length, and metal distribution Fig. shows the volume-weighted particle size distributions (PSD) of BM1, BM2, and BM3, measured by laser diffraction and plotted against a logarithmic x-axis. Each BM sample exhibits a narrow and intense peak centered at ~15 μm. BM1 and BM2 have mean particle sizes of ~90 µm and ~65 µm, respectively, while BM3 shows a lower mean particle size of ~30 µm. This major difference arises due to the presence of two small peaks present in BM1 and BM2 at ~200 µm and ~600 µm respectively, suggesting that BM1 and BM2 have a small proportion of large particles. However, pyrolysis results in the reduction of PSD for the three BM samples (Fig. ), where pyrolyzed BM1, BM2, and BM3 have mean particle sizes of ~35 µm, ~30 µm, and ~20 µm respectively. The FBRM technique to measure chord length distributions (CLD) of BM samples has not been widely adopted. Thus, PSD results for BM1, BM2, and BM3 (Fig. ) are employed as a reference to establish a method for CLD measurement (as shown in Fig. ). The main difference between laser diffraction and FBRM techniques arises from their working principles; laser diffraction works by passing a laser through a dispersed sample, and measuring the angular distribution of scattered light to calculate particle sizes over the entire sample. While the FBRM technique works by rotating a focused beam in a circular path at a fixed speed that only analyzes particles encountered by the beam, and measures the backward scattered light. The generated CLD, thus, only represents the segments of particles encountered by the beam. It is important to note that CLD measurements are significantly affected by the weighting method applied to the CLD curves, particularly in polydisperse samples such as BM. No weighting provides an unbiased mean size but does not differentiate between small and large particles. Length weighting increases sensitivity to larger particles, which is useful when characterizing elongated particles. Square weighting shifts the mean towards the coarser size ranges, making them valuable for detecting changes in larger particle populations. In this study, the effect of no weighting and square weighting on FBRM results have been analyzed as shown in Fig. and Fig. , respectively, and the results are correlated to the PSD measurements in Fig. . Fig. shows that CLD with no weighting (plotted on a logarithmic x-axis) has a distinct bi-modal distribution for the three BM samples where the first peak occurs at ~5 μm and the second peak at ~35 μm. According to CLD curves with no weight (Fig. ), BM1 and BM2 have a mean size of ~23 μm and ~20 μm, and BM3 shows a mean size of ~15 μm. These findings are noticeably different than those from the PSD measurement in Fig. . None of the BM samples show a peak at a higher size range like the ones detected in PSD of BM1 and BM2 (Fig. ). This can be attributed to the fact that no weighting is applied and thus any contributions from a small proportion of larger particles are minimized. Fig. shows that applying a square weighting to the CLD curves lessens the contributions from a smaller size range and enhances the presence of larger particles. The square-weighted CLD measurements plotted against the logarithmic x-axis (Fig. ) show a pronounced peak centered at ~50 µm, with BM1, BM2, and BM3 exhibiting nearly similar distributions with some variations at higher size ranges. The results show that BM1 has a mean size of ~90 μm, BM2 has a mean size of 66 μm and BM3 shows a comparatively lower mean size of ~50 μm (Fig. ). The square-weighted CLD results are more in line with the vol. weighted PSD results (Fig. ) and exhibit the same trend i.e., BM3 has a noticeably lower mean size. The square-weighted CLD measurements of pyrolyzed BM1, pyrolyzed BM2, and pyrolyzed BM3 (Fig. ) also show the same trend as seen in PSD analysis of pyrolyzed BM (Fig. ). Square-weighted CLD measurements using FBRM can be used to optimize pre-treatment processes (such as milling and sieving) and recycling processes such as flotation of graphite. Xuexia Wang et. al. used the FBRM technique to study and improve the flotation of fine coal particles. Haung et. al. has also reported that the FRBM technique can be used to find the optimized collector dosage for the flotation of coal. Similar methodologies can be employed in the flotation of graphite from BM feed which also uses the same collector as coal (i.e., kerosene). Fig. shows that the three BM samples were sieved into four different size fractions of +150 µm, -150+90 µm, -90+63 µm, and -63 µm. The mass distribution of BM3 (Fig. ) shows that ~80 wt. % of the total mass is present in -63 µm fraction, while BM1 and BM2 have only ~55 wt. % and ~25 wt. % of the total sieved mass in -63 µm fraction. PSD (Fig. ) and squareweighted CLD (Fig. ) showed that BM3 has a significantly lower mean size than BM1 and BM2, and this is also evident by the sieving pre-treatment (Fig. ). Additionally, BM1 shows comparatively higher mass (wt. %) in the +150 µm (10 wt. %), -150+90 μm (15 wt. %) and -90+63 μm (50 wt. %) fractions compared to BM2 and BM3 due to its coarser size distribution as shown by its PSD results (Fig. ) and square weighted CLD (Fig. ) results. This varying mass distribution into different size ranges for BM1, BM2, and BM3 can be exploited to optimize pre-treatment and recycling processes. Fig. shows the metal composition (wt. %) for the three BM samples where the wt. % of Li, transition metals (Ni, Mn, Co) and metallic current collectors (Al and Cu) have been measured. BM1 contains slightly higher Li (3.25±0.02 wt. %) compared to BM2 (2.15±0.01 wt. %) and BM3 (2.04±0.02 wt. %). The total mass (sum of wt. % of all metals) from metal composition results (Fig. ) only accounts for ~35 wt. % for BM1, ~27 wt. % for BM2 and ~30 wt. % for BM3. The remainder in each BM is mainly graphite and oxides as well as relatively small amounts of PVDF binder, electrolytes, and other organic species. Table shows the molar ratio of Ni:Mn:Co for the three BM samples and reveals that BM1, BM2, and BM3 could have been produced from NMC622 (Li[Ni0.6Mn0.2Co0.2]O₂), NMC111 (Li[Ni0.33Mn0.33Co0.33]O2), and NMC901 (Li[Ni0.9Mn0Co0.1]O₂) type end-of-life LIBs, respectively. However, further investigation of NMC phases in BM1, BM2, and BM3 using XRD is needed to confirm this. Fig. shows the normalized metal composition (wt. %) for BM1, BM2, and BM3 including the sieved fractions of each BM. Normalization of metal composition in Fig. enables a direct comparison of metal distribution among the fractions. The results show that metallic current collectors (Al and Cu) are primarily concentrated in the larger size fractions (+150 µm and -150+90 µm) across all three samples. The distribution of Ni, Mn, and Co remains relatively uniform across all size fractions while maintaining the molar ratio characteristic for each BM (Table ). During recycling of valuables, Al and Cu are usually considered metallic impurities, and the results from Fig. show that these impurities can be removed from smaller size fractions and concentrated in the coarser size fractions using sieving pretreatment. Yang et. al. have reported that Al and Cu impurities can be removed from larger-size fractions using froth flotation. 30