Study Of Production Ammonium Molybdate From Ni-Mo Ore

Ni-Mo ore is a complicated multi-metal mineral resource which is specific to China. The low-level technics of traditional extracting process has made huge waste of resources and grievous pollution to the local environment in exploiting of Ni-Mo ore. According to the property of Ni-Mo ore and present exploiting process, experimental processes of "entire hydrometallurgical process of leaching Ni-Mo ore with sodium hypochlorite(or Cl2)" and "one step roasting-calcine leaching with NaOH" were put forward for the first time. The study mainly focused on one step roasting, leaching of Ni-Mo calcine with NaOH, leaching of Ni-Mo ore with sodium hypochlorite, leaching of Ni-Mo ore with Cl2, Mo adsorption by ion exchange from low concentration solution, equilibrium and kinetics of Mo adsorption with D314 resin, removal of vanadium from ammonium molybdate solution by ion exchange, processing design of ammonium molybdate production from Ni-Mo ore. The achievement had been widely applied and high quality product of ammonium molybdate was obtained firstly from Ni-Mo ore which is in accordance with the standard of GB3460-82 for the first time, metal recovery was greatly improved, and the release of pollutant was reduced greatly. Main experimental results are as follows:In order to reduce discharge of powder in traditional process, "one step roasting-leaching of calcine with NaOH" was put forward. The effects of roasting temperature, roasting time, leaching temperature, leaching time, L/S of leaching, consumption of NaOH etc on leaching ratio of Mo from Ni-Mo calcine had been investigated. The experimental results show that leaching ratio was above 97% at the optimal condition.In order to avoid the release of powder and SO2, "entire hydrometallurgical process of leaching of Ni-Mo ore with sodium hypochlorite(or Cl2)" was put forward for first time. The effects of leaching temperature, concentration of NaClO, L/S of leaching, particle size of Ni-Mo ore, consumption of NaOH and Na2CO3, leaching time, and end pH etc on leaching ratio of Mo from Ni-Mo ore had been investigated. The experimental results show that leaching ratio of above 98% was obtained at the optimal condition. Test result also proved that NaCIO could selectively leach Mo from Ni-Mo ore, and selective coefficient reached 3.5.The test of leaching by Cl2 was put forward for the first time and carried out in self-made leaching vessel. The effects of temperature, consumption of NaOH, end pH, particle size of Ni-Mo ore, and L/S of leaching, and add velocity of Cl2 etc on leaching ratio of Mo from Ni-Mo ore was investigated. The experimental results show that leaching ratio of Mo above 96% was obtained at the optimal condition, the Mo concentration of leaching solution is about 6-12g/L, pH is 8-9.The results of selecting test of resin show that D314 resin is the best to adsorb Mo from weak acidic solution. Effects of pH of solution, concentration, and contact time of ion exchange on adsorption capability of Mo were investigated with fixed bed. The experimental results show that work adsorption capability of D314 resin to Mo was above 160mg/L at optimal conditions. The laden resin was desorbed by 10% ammonia and obtained above 120g/L Mo concentration of desorbed solution.The investigation of equilibrium and kinetics with D314 resin absorbing Mo was carried out for the first time. The experimental results show that adsorbed equilibrium time is about 240 minutes; When pH of solution is 3.5, saturation adsorption is 292.30mg/mL, distribution ratio is higher than 69411; by calculation of saturation adsorption of Mo and analysis of the form of molybdate in solution, molybdenum could be adsorbed by D314 through Mo4O132- from solution; Reaction control step of ion exchange is PDF, and the apparent activation energy is 27.30KJ/mol.The project that V(V) removal with chelate resins from ammonium molybdate solution is advanced for the first time. The experimental results show that chelate resins could adsorb vanadium preferentially from ammonium molybdate solution, but hardly adsorb Mo. Results of selecting resin show that DAS, CUW and CW-2 resins have higher adsorption capacity to vanadium than others. Effects of temperature, pH and adsorbing time to removal of vanadium were investigated, experimental results in fixed bed show that more than 99.5% of V(â…¤) can be adsorbed, but adsorbing ratio of Mo(â…¥) is less than 0.27%, separation coefficient of vanadium and molybdenum reached 126172,108097 and 105209 respectively at optimal conditions. According to the structure of chelate resins and the form of V(â…¤) in ammonium molybdate solution, mechanism of adsorbing V(â…¤) with chelate resin in ammonium molybdate solution was advanced for first time.According to the results achieved, two new processing flows of production ammonium molybdate from Ni-Mo ore were put forward, which are "leaching by NaClO-enrichment and transformation by ion exchange-purifying-removal of vanadium by ion-exchange-crystallization of ammonium molybdate by acidification" and "one step roasting-leaching by NaOH-enrichment and transformation by ion exchange-purifying-removal of vanadium by ion-exchange-crystallization of ammonium molybdate by acidification". The two processes succeeded in industrialization, and obtained enormous economic profit and environment protecting efficiency.