废旧轮胎回收利用技术及其应用前景

对废旧轮胎的各种回收利用技术进行了介绍，废旧轮胎的回收利用方法很多，其中有直接利用方法，包括翻新、用于建筑材料、原形改制等；还有间接利用方法，包括生产再生胶、胶粉、热利用、热裂解等。在此基础上，对我国废旧轮胎回收利用方面存在的问题进行了分析并提出了相应的发展建议。     

轮胎翻修节能环保将成为市场新亮点

介绍了国外企业废旧轮胎回收综合利用的新技术，并指出了再生胶工业快速发展前景和循环经济助推废旧轮胎回收利用的新商机。     

专利资讯

专利名称:利用废旧轮胎制取再生胶系统专利申请号:CN201620988982公开号:CN209078969U申请日:2016.08.31公开日:2019.07.09申请人:浙江菱正环保科技有限公司本实用新型属于废旧轮胎、橡胶等处理装置制造技术领域,尤其涉及利用废旧轮胎制取再生胶系统。利用废旧轮胎制取再生胶系统,包括轮胎切圈机、轮胎破碎机、胶块撕碎机、励磁磁选机、胶粒纤维分离器、橡胶磨粉机、气流分选机和脱硫精炼机,废旧轮胎依次通过轮胎切圈机、轮胎破碎机、胶块撕碎机、励磁磁选机、胶粒纤维分离器、废铁回收机、橡胶磨粉机、气流分选机和脱硫精炼机形成再生胶。本实用新型提供了一种生产效率高、效果好的利用废旧轮胎制取再生胶系统。     

废旧橡胶胶粉化 废旧橡胶胶粉化再生胶工业的发展方向

再生胶一直是世界橡胶工业的重要原材料,它一方面可以代替橡胶,缓解了天然橡胶严重匮乏的局面;另一方面使废旧橡胶实现了回收再利用,解决了废旧橡胶污染环境的问题。然而,随着合成橡胶的大量开发和应用,再生胶的应用开始萎缩。20世纪80年代末期,欧美主要工业国家开始停止通用型再生胶的生产,逐步转为将废旧橡胶直接加工成不同细度的胶粉直接利用。     

废旧橡胶利用亟待产业化

随着经济的不断发展,废旧橡胶,尤其是废旧轮胎正日益成为我国环保领域的一大难题。有关专家认为,回收利用并达到产业化规模才是废旧橡胶的真正出路。 资料显示,我国2000年共消耗生胶200万吨,居世界第二位,橡胶制品产量约2800万吨。按15％生成率计算,实际废旧橡胶的生成量约为420万吨,而2000年利用废旧橡胶生产出的再生胶仅为33万吨,橡胶粉为2．5万吨,仅为废旧橡胶总量的8％左右。此外,由于现在废旧橡胶再生利用技术相对落后,贵重的氟橡胶、硅橡胶、特种合成橡胶,包括氯丁橡胶、氯磺化聚乙烯橡胶等都没有得到有效的利用,这意味着我国废旧橡胶的回收利用尚处于起步阶段。     

十年来我国废旧橡胶(轮胎)利用专利及启示

党和政府近几年来,高度重视知识产权建设和保护工作。废旧橡胶利用(含轮胎翻新)是再生资源利用重点行业之一。从数据库中选取2009—2019年废旧橡胶行业专利申请情况,并根据行业现状进行分类整理和分析研究,有针对性地提出行业知识产权建设和保护工作的若干建议。在引起废旧橡胶利用(含轮胎翻新)行业重视基础上,进一步推动再生资源回收利用行业知识产权建设和保护工作的发展。     

借鉴国际经验促进我国废旧轮胎的再生利用

1 废旧轮胎的再生利用亟待改进 汽车等用的轮胎,由橡胶、碳黑、油软化剂、硫化剂和促进剂、子午线纲丝及纤维等组成,故在市场经济发达国家除对废旧轮胎翻修后再利用和制成胶粉供原料利用外,还利用其发热量高达7 500～8 000 kcal/kg的优势及其它特点,广泛用于燃料和建筑材料,故总的再生利用率已达88%～90%的水平.遗憾的是我国长期停留在轮胎翻修、生产再生胶和胶粉的较小范围,故废旧轮胎的再生利用率长期停留在65%左右,非常不适应形势发展的需要.     

我国废旧橡胶利用的发展趋势

废旧橡胶其来源主要是废橡胶制品,即报废的轮胎、胶管、胶带、车胎、胶鞋、工业杂品等,另外一部分来自橡胶厂生产过程中产生的边角余料和废品。 　　我国是一个橡胶应用大国,同时我国又是一个橡胶资源短缺的国家,几乎每年橡胶消耗量的45%左右需要进口,而且短时期内不会有根本的解决办法,由此可见,处理好废旧橡胶,对于充分利用再生资源,摆脱自然资源匮乏,减少环境污染,改善人类的生存环境是非常重要的。 　　我国废旧橡胶利用方法主要是制造再生橡胶和制造胶粉。 　　我国再生胶生产,建国初期产量在千吨左右,50～60年代生产工艺以水油法为主,70年代建设了19家水油法再生胶厂,80年代推广动态脱硫法代替水油法,全国约装置了300多台动态脱硫罐,较好地解决了废水污染问题。尽管如此,生产再生胶仍存在能耗大,生产效率低,污染环境,生产工艺流程长等缺点。所以,目前工业发达国家大多停止生产再生胶。     

废旧轮胎热裂解残渣资源化利用工艺研究进展

废旧轮胎的处理在交通与环保领域一直是世界重大课题。我国作为轮胎生产及使用大国,对废旧轮胎热裂解残渣资源化利用,研究从中回收可用于轮胎橡胶增强剂的炭黑工艺,一直备受关注。分析国内外废旧轮胎热裂解残渣提纯技术研究进展,总结环境友好及利润率高的几种工艺,通过分析我国废旧轮胎处理产业的发展现况,从环保方面对老旧工艺提出了建议。     

我国废旧地膜回收利用及相关标准现状分析

促进废旧地膜的回收利用,对于治理地膜污染、保护农田生态环境、推进农业清洁生产具有重要意义。为加快推进废旧地膜的机械化收集、专业化回收以及资源化利用,简要分析了我国废旧地膜回收利用的现状、存在问题和发展趋势,并对我国现有的废旧地膜回收利用相关标准进行了检索和统计,总结和分析了我国现行地膜回收的国家标准、行业标准和地方标准,提出了制定废旧地膜回收利用相关标准的需求及建议。     

Determination of the Thermal Efficiency of Pre-boilover Burning of a Slick of Oil on Water

The burning rate of a slick of oil on a water bed is calculated by a simple expression derived from a one-dimensional heat conduction equation. Heat feedback from the flame to the surface is assumed to be a constant fraction of the total energy released by the combustion reaction. The constant fraction (χ) is named the burning efficiency and represents an important tool in assessing the potential of in situ burning as a counter-measure to an oil-spill. The total heat release, as a function of the pool diameter, is obtained from an existing correlation. It is assumed that radiative heat is absorbed close to the fuel surface, that conduction is the dominant mode of heat transfer in the liquid phase and that the fuel boiling temperature remains constant. By matching the characteristic thermal penetration length scale for the fuel/water system and an equivalent single layer system, a combined thermal diffusivity can be calculated and used to obtain an analytical solution for the burning rate. Theoretical expressions were correlated with crude oil and heating oil, for a number of pool diameters and initial fuel layer thickness. Experiments were also conducted with emulsified and weathered crude oil. The simple analytical expression describes well the effects of pool diameter and initial fuel layer thickness permitting a better observation of the effects of weathering, emulsification and net heat feedback to the fuel surface. Experiments showed that only a small fraction of the heat released by the flame is retained by the fuel layer and water bed (of the order of 1%). The effect of weathering on the burning rate decreases with the weathering period and that emulsification results in a linear decrease of the burning rate with water content.     

富拉尔基发电总厂200MW机组除尘器改造

对富拉尔基发电总厂5号炉的设计条件进行了分析，针对燃用低硫煤，飞灰比电阻高，场地较小，除尘效率要求高的情况，在电除尘器的设计上采取有效措施，达到了排放要求。     

Calculation of carbon balances for evaluation of the biodegradability of polymers

Establishing carbon balances has been proven to be an applicable and powerful tool in testing biodegradability of polymers. In controlled degradation tests at a 4-L scale with the model polymer poly(-hydroxybutyrate) (PHB), it was shown that the degree of degradation could not be determined with satisfactory accuracy from CO₂ release alone. Instead, the course of degradation was characterized by means of establishing carbon balances for the degradation of PHB withAcidovorax facilis and a mixed culture derived from compost. Different analytical methods for determining the different carbon fractions were adapted to the particular test conditions and compared. Quantitative determination of biomass and residual polymer were the main problems in establishing carbon balances. Amounts of biomass derived from protein measurements depend strongly on assumptions of the protein content of the biomass. Selective oxidation of biomass with hypochlorite was used as alternative, but here problems arose from insoluble metabolic products. Determination of soluble components with the method of chemical oxygen demand (COD) also includes empirical assumptions but seems acceptable if the dissolved carbon fraction is in the range of some 10% total carbon. Results confirm both analytical assays and theoretical approaches, in ending up at values very close to 100%, within an acceptable standard deviation range under test conditions comparable to standard test practice.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.     

Review of the kinetics of alkaline degradation of cellulose in view of its relevance for safety assessment of radioactive waste repositories

The degradation of cellulose (a substantial component of low- and intermediate-level radioactive waste) under alkaline conditions occurs via two main processes: a peeling-off reaction and a basecatalyzed cleavage of glycosidic bonds (hydrolysis). Both processes show pseudo-first-order kinetics. At ambient temperature, the peeling-off process is the dominant degradation mechanism, resulting in the formation of mainly isosaccharinic acid. The degradation depends strongly on the degree of polymerization (DP) and on the number of reducing end groups present in cellulose. Beyond pH 12.5, the OH^- concentration has only a minor effect on the degradation rate. It was estimated that under repository conditions (alkaline environment, pH 13.3-12.5) about 10% of the cellulosic materials (average DP = 1000-2000) will degrade in the first stage (up to 10⁵ years) by the peeling-off reaction and will cause an ingrowth of isosaccharinic acid in the interstitial cement pore water. In the second stage (10⁵-10⁶ years), alkaline hydrolysis will control the further degradation of the cellulose. The potential role of microorganisms in the degradation of cellulose under alkaline conditions could not be evaluated. Proper assessment of the effect of cellulose degradation on the mobilization of radionuclides basically requires knowing the concentration of isosaccharinic acid in the pore water. This concentration, however, depends on several factors such as the stability of ISA under alkaline conditions, sorption of ISA on cement, formation of sparingly soluble ISA-salts, etc. A discussion of all the relevant processes involved, however, is far beyond the scope of the presented overview.     

Study of Aging Characteristics of Ternary Blends of Polyethylenes—II

Six film samples of low-density polypropylene (LDPE)/linear LDPE (LLDPE)/high-density polypropylene (HDPE) with varying ratios of LDPE (20–45 ... wt%) and LLDPE (25–50 wt%) having a fixed amount of HDPE at 30 wt% were prepared by blown film extrusion technique. The samples were aged at four different temperatures, 55°, 70°, 85°, and 100°C, for four different time periods in the interval of between 150 hours and up to 600 hours. The change in the structure of various constituents and the formation of various oxygenated (peroxy and hydroperoxy) and unsaturated groups during thermo-oxidative degradation was discussed by infrared spectroscopy. The visiosity-average molecular weight was found to have decreased slowly in the initial aging hours and temperatures, whereas it decreased by 10% with its previous value tensile strength that is, 100°C when aged for 600 hours. The tensile strength of the sample first increased by 67% at 55°C and 89% at 70°C up to 450 hours, whereas the values increased by 52.5% at 85°C and 33.9% at 100°C when aged for 150 hours and then decreased. The percentage elongation at break increased by 2.7% at 55°C and 10.7% at 70°C for 150 and 300 hours of aging, respectively, whereas the percentage decreased when aged at 85°C and 100°C for up to 600 hours of aging. The values of gel content (percent) increased and initial degradation temperature decreased with aging time and temperature.     

Effect of Degree of Substitution of Octenyl Succinate Starch on Enzymatic Degradation

Octenyl succinate starch of degree of substitution (ds) 0.03, 0.07, and 0.11 was synthesized in an aqueous medium. These compounds were then tested for the susceptibility to enzymatic degradation. The multiple-enzyme regime of -amylase, amyloglucosidase, and pullulanase was chosen for the evaluation. This combination of enzymes had been proven to degrade 99.5% of unmodified starch to glucose and hence was chosen for this study. It was found that even small amounts of subsituent caused a considerable decrease in the extent of degradation. The net extent of degradation decreased with increasing ds. Surprisingly, the amount of glucose from all three substituted substrates was quite similar, suggesting the effect small amounts of subtituent had on the enzymatic activity.     

Selection of adsorbents for treatment of leachate: batch studies of simultaneous adsorption of heavy metals

The simultaneous adsorption of copper (Cu), cadmium (Cd), nickel (Ni), and lead (Pb) ions from spiked deionized water and spiked leachate onto natural materials (peat A and B), by-product or waste materials (carbon-containing ash, paper pellets, pine bark, and semi-coke), and synthetic materials (based on urea-formaldehyde resins, called blue and red adsorbents) or mixtures thereof was investigated. The adsorbents that gave the highest metal removal efficiencies were peat A, a mixture of peat B and carbon-containing ash, and a mixture of peat A and blue. At an initial concentration of 5 mg/l for each metal, the removal of each species of metal ion from spiked water and spiked leachate solutions was very good (>90%) and good (>75%), respectively. When the initial concentration of each metal in the solutions was twenty times higher (100 mg/l), there was a noticeable decrease in the removal efficiency of Cu²⁺, Cd²⁺, and Ni²⁺, but not of Pb²⁺. Langmuir monolayer adsorption capacities, q_m, on peat A were found to be 0.57, 0.37, and 0.36 mmol/g for Pb²⁺, Cd²⁺, and Ni²⁺, respectively. The order of metal adsorption capacity on peat A was the same in the case of competitive multimetal adsorption conditions as it was for single-element adsorption, namely Pb²⁺ > Cd²⁺ ≥ Ni²⁺. The results show that peat alone (an inexpensive adsorbent) is a good adsorbent for heavy metal ions.     

袋式除尘器气流分布数值计算研究

采用结构化/非结构化混合网格技术、多孔介质模型及k-ε两方程湍流模型,对某袋式除尘器及进出口管道内的气体流场进行了数值计算.计算结果表明,合理布置导流板后,袋式除尘器两箱体流量偏差为1.8％;除尘器下游滤袋单元处理气量偏大,中游滤袋单元处理气量较小,最大流量与最小流量偏差为22.3％；靠近除尘器进口处灰斗内存在气流回流特性,易造成粉尘的二次附着现象.     

Effects of temperature on the release of nutrient elements of solid organic materials under conditions of oversaturation

The effects of temperature on the release of chemical components of six solid organic materials under conditions of oversaturation were investigated in this paper. The six materials were peat moss (PM), weathered coals (WC), charred rice husks (CRH), sawdust (Sd), turfgrass clippings (TC), and chicken manure (CM). Significant differences were observed in the available nitrogen and phosphorus content of the aqueous extracts of organic materials at different temperatures. The available nitrogen content in aqueous extracts of PM and WC at 25 °C was higher than that registered at 15 °C and 35 °C. Available nitrogen content in the aqueous extracts of CRH, Sd, TC, and WC at 35 °C was higher than at 15 °C and 25 °C. The available phosphorus content in the aqueous extracts of organic materials at 35 °C was higher than that available at 15 °C and 25 °C, with the exception of Sd. In addition, the release of available phosphorus in the aqueous solution of organic materials at different temperatures varied constantly for 108 h. The release of potassium (K⁺) and sodium (Na⁺) ions in the aqueous extracts of organic materials was basically steady over time, with the exception of CM. High temperature (35 °C) may significantly hasten the release of K⁺ from organic substrates (except for WC) with low temperatures significantly inhibiting release of K⁺ in Sd and CRH. High temperatures (35 °C) might significantly facilitate the release of Na⁺ in CM and TC. However, no significant differences were manifested in the release of Na⁺ from organic substrates at different temperatures, with the exception of CM and TC. Moreover, no significant differences were observed in the release of calcium, magnesium and iron ions with time, nor were there any significant differences in the contents of iron ions in the aqueous extracts of organic materials at different temperatures. The results indicate that multiple mediums should be pretreated in water for a week before being used for planting. They should be used when all mineral elements of organic materials are steady and ignoring the effect of organic mediums.     

Kinetics of Hydrolytic Degradation of PLA

The chemical recycling of poly(lactic acid) (PLA) to its monomer is crucial to reduce both the consumption of renewable resources for the monomer synthesis and the environmental impact related to its production and disposal. In particular, the production of lactic acid from PLA wastes, rather than from virgin raw materials, it is also possible to achieve considerable primary energy savings. The focus of this work is to analyse deeply the PLA hydrolytic decomposition by means of a kinetic model based on two reactions mechanism. To this end, new experimental data have been gathered in order to investigate a wider temperature range (from 140 to 180 °C) and to extend the water/PLA ratio up to 50 % of PLA by weight. The reported results clearly highlight that more than 95 % of PLA is hydrolyzed to water-soluble lactic acid within 120 min, when it is hydrolyzed within 160–180 °C. Furthermore, the kinetic constant is highly influenced by reaction temperature. The proposed “two reactions” kinetic mechanism complies satisfactorily with the experimental data under analysis.