[tex]1g=1000mg\to1mg=0.001g\\1min=60s\to1s=\frac{1}{60}min\\\\\\5.8\times10^6\ mg/s=5.8\times10^6\times\frac{0.001g}{\frac{1}{60}min}=5.8\times10^6\times0.001\times60\ g/min\\\\=5.8\times10^3\times60\ g/min=348\times10^3\ g/min=\boxed{3.48\times10^5\ g/min}[/tex]