Study On Gypsum Retarder From Waste Penicillin Mycelium And Application In Plaster

Waste penicillin mycelium(WPM) is a harmful solid waste from the production process of penicillin in pharmaceutical factory. If not handled properly, it will bring thorny issues to the manufacturers and will cause serious pollution to the environment. In this paper, a process was proposed to prepare gypsum retarder from WPM with activated carbon being by product, solving the environmental and safety problems resulting from current treatment process.It was found in our study that waste mycelium contains a large amount of proteins which may be used to extend the setting time of gypsum. The proteins, in this paper, were extracted from the WPM by soaking and extraction process, which can be used as FGD gypsum retarder, named WPM retarder. The results indicated that the optimum soaking conditions were temperature 80 ℃, treatment time 90 min and pH value 11. Activated carbon was prepared form the filter residue of WPM. The iodine value of the produced activated carbon is 574 mg/g, methylene blue value 14.27 mg/g, specific area 167 m2/g. The activated carbon produced in this process can meet the requirements of general industrial applications.Compared with citric acid, sodium citrate and sodium polyphosphate, WPM retarder can effectively prolong the setting time of gypsum with less influence on mechanical strength. The crystal morphology microstructure of gypsum containing retarder was studied with SEM. The SEM photos show that the sample with WPM has less influence on crystal morphology microstructure of gypsum. The retarding mechanism of WPM retarder relies on the dissolved functional groups of peptide bond, amidogen and carboxyl group, which can reacts with solved Ca2+ ions to produce a complex compound and cover the surface of the gypsum particles and hinders its further dissolution. Ca2+ is kept in solution through complexation, and the growth of initial crystals is impeded by WPM adsorption. The setting time of gypsum is thus prolonged.WPM retarder was used as retarder for preparation of gypsum plasters. On the basis of systematic experiments, the appropriate material proportioning of gypsum plaster for finish coating was obtained: gypsum 94 %, cement 2 %, superfine slag 4 %, HPMC 0.5 % and WPM retarder 0.1 %~0.15 %. The appropriate material proportioning of gypsum plaster for base coating was obtained: fine sand 60 %, gypsum 37.6 %, cement 0.8 %, superfine slag 1.8 %, HPMC 0.2 % and WPM retarder 0.06 %. The appropriate material proportioning of thermal insulation gypsum plaster was obtained: expanded perlite 28.6 %, gypsum 67.2 %, cement 1.4 %, superfine slag 2.8 %, HPMC 0.71 % and WPM retarder 0.11 %. All the products of plasters conform to "JCT517-2004".With an annual output of 1 000 tons of WPM retarder process being an example, the economic benefit was calculated. The results showed that, this product not only can realize the resource utilization of solid waste, but also save cost effectively. This approach processes excellent economic, social and environmental benefits, and has a good development prospects.