Superabsorbent dewatering of refractory gold concentrate slurries

In this paper, superabsorbent polymer (SAB) dewatering behaviour of selected mineral pulps comprising low-grade, refractory gold flotation concentrate, bio-oxidation product and cyanide leach residue was investigated as an alternative to conventional, gravity thickening. The shear rheology of the resulting sediments was also investigated for pulp handleability. All slurries displayed better SAB-mediated dewatering performance, in terms of reduced processing time, volume minimization and greater water recovery for recycle, in comparison with gravity thickening. Specifically, SAB absorbed >94 wt.% water from the dilute slurries within 30 min of contact time. 45–76 wt.% more water was recovered after 60 min at high supernatant clarity using the SAB dewatering approach compared with gravity settling. The observed non-Newtonian, shear thinning rheological behaviour of SAB-dewatered consolidated slurries, reflecting low to moderate yield stresses in the range 1–40 Pa and shear thinning viscosities (<10 mPa⋅s), indicate their “handleability” in hydro-transport. The cost effectiveness of the SAB dewatering process engendered by its significantly greater water recovery and SAB polymer recovery, regeneration and multiple reuse capacity.     

Analysis of energy efficiency and carbon dioxide reduction in the Chinese pulp and paper industry

Pulp and paper production, an energy-intensive process, is among the main light industries contributing to energy saving and pollution emission reduction in China. The improvement of energy efficiency is essential for energy consumption and sustainable development. This study analyzes the negative factors in the pulp and paper sector by calculating energy efficiency from the lengthways time and investigating the gap between China and foreign countries through a horizontal comparison. Accordingly, energy efficiency has increased in the Chinese pulp and paper industry with years of efforts, but its transformation remains unclear. Furthermore, the energy-saving potential, energy cost saving, and carbon dioxide emission reduction in the pulp and paper industry are evaluated according to the Twelfth Five-year Plan (2011–2015). The results show that the pulp and paper industry has further capabilities for energy-saving and carbon dioxide emission reduction by improving energy efficiency in China, resulting in great economic benefit. In brief, new technology and energy structure adjustment are long-term strategies for energy conversation, with changes in the scale of mills expected to provide huge opportunities to improve energy efficiency in China within a short period.     

造纸黑液制水煤浆与集成膜资源化处理技术可行性探讨

介绍了黑液水煤浆技术，黑液膜处理技术，集成膜技术。依据世界科技创新常用形式之一是科技集成，而膜技术与其它成熟技术或膜技术之间的集成技术是解决现代工业问题的重要趋势。笔者提出适合中国国情的造纸黑液煤浆与膜集成资源化处理技术方案。以废物资源化处理的理念，集成高科技膜分离技术与水煤浆等洁净煤技术，资源化处理造纸黑液的同时，综合治理高硫燃煤二氧化硫污染，是技术、经济可行的创新集成技术。     

Physicochemical and Bioactive Compounds of ‘Cantaloupe’ Melon: Effect of Ozone Processing on Pulp and Seeds

Melon seeds are an important source of bioactive compounds, which are considered to be health beneficial. Therefore, the objective of this work was to assess the impact of gaseous ozone treatments (30 and 60 min) on melon seeds paste (nonedible part) and compare with the effect on pulp (edible part). Ozone treatments were evaluated in terms of physicochemical (color, pH, and soluble solids content) and nutritional profiles (total phenolics, total carotenoids, and total antioxidant capacity) of processed material. Results indicate that ozone has a different impact on the two fruit matrices, being seeds less affected by this preservation treatment.     

Effect of biological wastewater treatment on the molecular weight distribution of soluble organic compounds and on the reduction of BOD, COD and P in pulp and paper mill effluent

Pulp and paper mill wastewater was characterizated, before (influent) and after (effluent) biological wastewater treatment based on an activated sludge process, by microfiltration (8, 3, 0.45 and 0.22mum) and ultrafiltration (100, 50, 30 and 3kDa) of the wastewater samples into different size fractions. Various parameters were measured on each fraction: molecular weight distribution (MWD) using high performance size exclusion chromatography (HPSEC), total organic carbon (TOC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (Tot-P), phosphate phosphorus (PO(4)-P), electrical conductivity, pH, turbidity, charge quantity and zeta potential. The MWD, TOC and COD(Cr) results indicated that the majority of the material present in both the influent and effluent was in the medium molecular weight (MW) range (i.e. MW<10kDa) with three main MW sub-fractions. There were no significant differences in the range of the MWD between the influent and effluent samples. The magnitude of the MWD in the effluent was about one half that in the influent, the greatest reduction being in the 6kDa fraction. The 3kDa fractions of both the influent and effluent showed a considerable increase in BOD(7), probably due to the removal of compounds harmful to bacteria in 3kDa ultrafiltration. Influent turbidity decreased considerably in microfiltration (8-0.22mum). As the turbidity was removed by 0.22mum filtration, the anionic charge quantity started to decrease. Particles in the influent and effluent contained 19-29% and 14-20% of the total phosphorus, respectively. The major phosphorus fraction was in the form of soluble phosphate.     

北京什刹海烟袋斜街地区保护整治实践

在北京编制完成25片历史文化保护区保护规划之后,为了恢复烟袋斜街的传统商业和活力．北泵市西城区政府于2001年开始对烟袋斜街地区进行了保护和整治改造。本文介绍了街道改造的指导思想实施过程和效果,以及相关主体的利益互动。通过对烟袋斜街整治改造案例的分析，本文提出适度政府干预对历史街区再生的积极意义。     

Control of chemical processes using neural networks: implementation in a plant for xylose production

This work demonstrates the use of artificial intelligence for control of xylose reactor performance in a paper factory. Two types of neural networks are used, a perceptron for the temperature controller and an adaptive formulation for the noise filter. The results show an improvement in the temperature stabilization time with respect to a classic PID control.     

串口通讯在制浆造纸生产中的应用

针对当前我国流程工业生产线,特别是制浆造纸自动化改造过程中面临的网络投入过大、维护复杂等不足,在总结对比了目前的几种常用网络之后,提出了基于串口通讯的低成本解决方案,并结合一具体磨浆机系统改进方案,详细介绍了方案的实施过程。该方案的成功应用也证明了采用串口通讯可以很好地弥补小型自动化系统中的高成本缺陷,有很好的推广应用价值。     

System analysis of hydrogen production from gasified black liquor

Hydrogen produced from renewable biofuel is both clean and CO₂ neutral. This paper evaluates energy and net CO₂ emissions consequences of integration of hydrogen production from gasified black liquor in a chemical pulp mill. A model of hydrogen production from gasified black liquor was developed and integration possibilities with the pulp mill's energy system were evaluated in order to maximize energy recovery. The potential hydrogen production is 59 000 tonnes per year if integrated with the KAM reference market pulp mill producing 630 000 Air dried tonnes (ADt) pulp/year. Changes of net CO₂ emissions associated with modified mill electric power balance, biofuel import and end usage of the produced hydrogen are presented and compared with other uses of gasified black liquor such as electricity production and methanol production. Hydrogen production will result in the greatest reduction of net CO₂ emissions and could reduce the Swedish CO₂ emissions by 8% if implemented in all chemical market pulp mills. The associated increases of biofuel and electric power consumption are 5% and 1.7%, respectively.