Abstract: A tuning-fork type crystal resonator includes a base portion, a first vibration arm and a second vibration arm, a supporting arm, a first connection pad and a second connection pad, and a first excitation electrode and a second excitation electrode. The first excitation electrode is extended from the first connection pad so as to reach a side surface of the first vibration arm on the supporting arm side via a region including a part of a principal surface of the supporting arm and a part of a side surface of the supporting arm on the first vibration arm side, an inner bottom surface of a first bifurcated portion present between the supporting arm and the first vibration arm, and a circumferential portion of the first bifurcated portion in the base portion. The second excitation electrode is extended at a second bifurcated portion similarly to the first excitation electrode.

Abstract: Provided is a hydrometallurgical process for nickel oxide ore by high pressure acid leach that achieves a high iron oxidation ratio. The carbon grade in ore slurry and the flow rate are measured to determine the amount of carbon to be fed, and then, sulfuric acid is added. The blowing ratio of high pressure air and high pressure oxygen is adjusted so as to attain an oxygen purity of 21% to 60%. While the oxygen purity is maintained, an oxygen blowing amount per weight of carbon contained in the ore slurry and fed in the second step is adjusted to 200 to 600 Nm3, whereby ORP (Ag/AgCl basis) in the leaching treatment is controlled to 400 to 650 mV.

Abstract: Provided is a hydrometallurgical process for nickel oxide ore by high pressure acid leach that achieves a high iron oxidation ratio. The carbon grade in ore slurry and the flow rate are measured to determine the amount of carbon to be fed, and then, sulfuric acid is added. The blowing ratio of high pressure air and high pressure oxygen is adjusted so as to attain an oxygen purity of 21% to 60%. While the oxygen purity is maintained, an oxygen blowing amount per weight of carbon contained in the ore slurry and fed in the second step is adjusted to 200 to 600 Nm3, whereby ORP (Ag/AgCl basis) in the leaching treatment is controlled to 400 to 650 mV.